Merge branch 'master' into fix_3803

41 files changed, 2354 insertions, 1639 deletions

diff --git a/src/core/lib/security/security_context.c b/src/core/lib/security/context/security_context.c
index 343e0b5b8b..127b13ee50 100644
--- a/src/core/lib/security/security_context.c
+++ b/src/core/lib/security/context/security_context.c
@@ -33,7 +33,7 @@
 
 #include <string.h>
 
-#include "src/core/lib/security/security_context.h"
+#include "src/core/lib/security/context/security_context.h"
 #include "src/core/lib/support/string.h"
 #include "src/core/lib/surface/api_trace.h"
 #include "src/core/lib/surface/call.h"
diff --git a/src/core/lib/security/security_context.h b/src/core/lib/security/context/security_context.h
index 81161ec47d..ef0c06b1fb 100644
--- a/src/core/lib/security/security_context.h
+++ b/src/core/lib/security/context/security_context.h
@@ -31,11 +31,11 @@
  *
  */
 
-#ifndef GRPC_CORE_LIB_SECURITY_SECURITY_CONTEXT_H
-#define GRPC_CORE_LIB_SECURITY_SECURITY_CONTEXT_H
+#ifndef GRPC_CORE_LIB_SECURITY_CONTEXT_SECURITY_CONTEXT_H
+#define GRPC_CORE_LIB_SECURITY_CONTEXT_SECURITY_CONTEXT_H
 
 #include "src/core/lib/iomgr/pollset.h"
-#include "src/core/lib/security/credentials.h"
+#include "src/core/lib/security/credentials/credentials.h"
 
 /* --- grpc_auth_context ---
 
@@ -111,4 +111,4 @@ grpc_auth_context *grpc_auth_context_from_arg(const grpc_arg *arg);
 grpc_auth_context *grpc_find_auth_context_in_args(
     const grpc_channel_args *args);
 
-#endif /* GRPC_CORE_LIB_SECURITY_SECURITY_CONTEXT_H */
+#endif /* GRPC_CORE_LIB_SECURITY_CONTEXT_SECURITY_CONTEXT_H */
diff --git a/src/core/lib/security/credentials.c b/src/core/lib/security/credentials.c
deleted file mode 100644
index 1c9832333a..0000000000
--- a/src/core/lib/security/credentials.c
+++ /dev/null
@@ -1,1299 +0,0 @@
-/*
- *
- * Copyright 2015, Google Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
-
-#include "src/core/lib/security/credentials.h"
-
-#include <stdio.h>
-#include <string.h>
-
-#include "src/core/lib/channel/channel_args.h"
-#include "src/core/lib/channel/http_client_filter.h"
-#include "src/core/lib/http/httpcli.h"
-#include "src/core/lib/http/parser.h"
-#include "src/core/lib/iomgr/executor.h"
-#include "src/core/lib/json/json.h"
-#include "src/core/lib/support/string.h"
-#include "src/core/lib/surface/api_trace.h"
-
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
-#include <grpc/support/sync.h>
-#include <grpc/support/time.h>
-
-/* -- Common. -- */
-
-struct grpc_credentials_metadata_request {
-  grpc_call_credentials *creds;
-  grpc_credentials_metadata_cb cb;
-  void *user_data;
-};
-
-static grpc_credentials_metadata_request *
-grpc_credentials_metadata_request_create(grpc_call_credentials *creds,
-                                         grpc_credentials_metadata_cb cb,
-                                         void *user_data) {
-  grpc_credentials_metadata_request *r =
-      gpr_malloc(sizeof(grpc_credentials_metadata_request));
-  r->creds = grpc_call_credentials_ref(creds);
-  r->cb = cb;
-  r->user_data = user_data;
-  return r;
-}
-
-static void grpc_credentials_metadata_request_destroy(
-    grpc_credentials_metadata_request *r) {
-  grpc_call_credentials_unref(r->creds);
-  gpr_free(r);
-}
-
-grpc_channel_credentials *grpc_channel_credentials_ref(
-    grpc_channel_credentials *creds) {
-  if (creds == NULL) return NULL;
-  gpr_ref(&creds->refcount);
-  return creds;
-}
-
-void grpc_channel_credentials_unref(grpc_channel_credentials *creds) {
-  if (creds == NULL) return;
-  if (gpr_unref(&creds->refcount)) {
-    if (creds->vtable->destruct != NULL) creds->vtable->destruct(creds);
-    gpr_free(creds);
-  }
-}
-
-void grpc_channel_credentials_release(grpc_channel_credentials *creds) {
-  GRPC_API_TRACE("grpc_channel_credentials_release(creds=%p)", 1, (creds));
-  grpc_channel_credentials_unref(creds);
-}
-
-grpc_call_credentials *grpc_call_credentials_ref(grpc_call_credentials *creds) {
-  if (creds == NULL) return NULL;
-  gpr_ref(&creds->refcount);
-  return creds;
-}
-
-void grpc_call_credentials_unref(grpc_call_credentials *creds) {
-  if (creds == NULL) return;
-  if (gpr_unref(&creds->refcount)) {
-    if (creds->vtable->destruct != NULL) creds->vtable->destruct(creds);
-    gpr_free(creds);
-  }
-}
-
-void grpc_call_credentials_release(grpc_call_credentials *creds) {
-  GRPC_API_TRACE("grpc_call_credentials_release(creds=%p)", 1, (creds));
-  grpc_call_credentials_unref(creds);
-}
-
-void grpc_call_credentials_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_call_credentials *creds,
-    grpc_pollset *pollset, grpc_auth_metadata_context context,
-    grpc_credentials_metadata_cb cb, void *user_data) {
-  if (creds == NULL || creds->vtable->get_request_metadata == NULL) {
-    if (cb != NULL) {
-      cb(exec_ctx, user_data, NULL, 0, GRPC_CREDENTIALS_OK, NULL);
-    }
-    return;
-  }
-  creds->vtable->get_request_metadata(exec_ctx, creds, pollset, context, cb,
-                                      user_data);
-}
-
-grpc_security_status grpc_channel_credentials_create_security_connector(
-    grpc_channel_credentials *channel_creds, const char *target,
-    const grpc_channel_args *args, grpc_channel_security_connector **sc,
-    grpc_channel_args **new_args) {
-  *new_args = NULL;
-  if (channel_creds == NULL) {
-    return GRPC_SECURITY_ERROR;
-  }
-  GPR_ASSERT(channel_creds->vtable->create_security_connector != NULL);
-  return channel_creds->vtable->create_security_connector(
-      channel_creds, NULL, target, args, sc, new_args);
-}
-
-grpc_server_credentials *grpc_server_credentials_ref(
-    grpc_server_credentials *creds) {
-  if (creds == NULL) return NULL;
-  gpr_ref(&creds->refcount);
-  return creds;
-}
-
-void grpc_server_credentials_unref(grpc_server_credentials *creds) {
-  if (creds == NULL) return;
-  if (gpr_unref(&creds->refcount)) {
-    if (creds->vtable->destruct != NULL) creds->vtable->destruct(creds);
-    if (creds->processor.destroy != NULL && creds->processor.state != NULL) {
-      creds->processor.destroy(creds->processor.state);
-    }
-    gpr_free(creds);
-  }
-}
-
-void grpc_server_credentials_release(grpc_server_credentials *creds) {
-  GRPC_API_TRACE("grpc_server_credentials_release(creds=%p)", 1, (creds));
-  grpc_server_credentials_unref(creds);
-}
-
-grpc_security_status grpc_server_credentials_create_security_connector(
-    grpc_server_credentials *creds, grpc_server_security_connector **sc) {
-  if (creds == NULL || creds->vtable->create_security_connector == NULL) {
-    gpr_log(GPR_ERROR, "Server credentials cannot create security context.");
-    return GRPC_SECURITY_ERROR;
-  }
-  return creds->vtable->create_security_connector(creds, sc);
-}
-
-void grpc_server_credentials_set_auth_metadata_processor(
-    grpc_server_credentials *creds, grpc_auth_metadata_processor processor) {
-  GRPC_API_TRACE(
-      "grpc_server_credentials_set_auth_metadata_processor("
-      "creds=%p, "
-      "processor=grpc_auth_metadata_processor { process: %p, state: %p })",
-      3, (creds, (void *)(intptr_t)processor.process, processor.state));
-  if (creds == NULL) return;
-  if (creds->processor.destroy != NULL && creds->processor.state != NULL) {
-    creds->processor.destroy(creds->processor.state);
-  }
-  creds->processor = processor;
-}
-
-static void server_credentials_pointer_arg_destroy(void *p) {
-  grpc_server_credentials_unref(p);
-}
-
-static void *server_credentials_pointer_arg_copy(void *p) {
-  return grpc_server_credentials_ref(p);
-}
-
-static int server_credentials_pointer_cmp(void *a, void *b) {
-  return GPR_ICMP(a, b);
-}
-
-static const grpc_arg_pointer_vtable cred_ptr_vtable = {
-    server_credentials_pointer_arg_copy, server_credentials_pointer_arg_destroy,
-    server_credentials_pointer_cmp};
-
-grpc_arg grpc_server_credentials_to_arg(grpc_server_credentials *p) {
-  grpc_arg arg;
-  memset(&arg, 0, sizeof(grpc_arg));
-  arg.type = GRPC_ARG_POINTER;
-  arg.key = GRPC_SERVER_CREDENTIALS_ARG;
-  arg.value.pointer.p = p;
-  arg.value.pointer.vtable = &cred_ptr_vtable;
-  return arg;
-}
-
-grpc_server_credentials *grpc_server_credentials_from_arg(const grpc_arg *arg) {
-  if (strcmp(arg->key, GRPC_SERVER_CREDENTIALS_ARG) != 0) return NULL;
-  if (arg->type != GRPC_ARG_POINTER) {
-    gpr_log(GPR_ERROR, "Invalid type %d for arg %s", arg->type,
-            GRPC_SERVER_CREDENTIALS_ARG);
-    return NULL;
-  }
-  return arg->value.pointer.p;
-}
-
-grpc_server_credentials *grpc_find_server_credentials_in_args(
-    const grpc_channel_args *args) {
-  size_t i;
-  if (args == NULL) return NULL;
-  for (i = 0; i < args->num_args; i++) {
-    grpc_server_credentials *p =
-        grpc_server_credentials_from_arg(&args->args[i]);
-    if (p != NULL) return p;
-  }
-  return NULL;
-}
-
-/* -- Ssl credentials. -- */
-
-static void ssl_destruct(grpc_channel_credentials *creds) {
-  grpc_ssl_credentials *c = (grpc_ssl_credentials *)creds;
-  if (c->config.pem_root_certs != NULL) gpr_free(c->config.pem_root_certs);
-  if (c->config.pem_private_key != NULL) gpr_free(c->config.pem_private_key);
-  if (c->config.pem_cert_chain != NULL) gpr_free(c->config.pem_cert_chain);
-}
-
-static void ssl_server_destruct(grpc_server_credentials *creds) {
-  grpc_ssl_server_credentials *c = (grpc_ssl_server_credentials *)creds;
-  size_t i;
-  for (i = 0; i < c->config.num_key_cert_pairs; i++) {
-    if (c->config.pem_private_keys[i] != NULL) {
-      gpr_free(c->config.pem_private_keys[i]);
-    }
-    if (c->config.pem_cert_chains[i] != NULL) {
-      gpr_free(c->config.pem_cert_chains[i]);
-    }
-  }
-  if (c->config.pem_private_keys != NULL) gpr_free(c->config.pem_private_keys);
-  if (c->config.pem_private_keys_sizes != NULL) {
-    gpr_free(c->config.pem_private_keys_sizes);
-  }
-  if (c->config.pem_cert_chains != NULL) gpr_free(c->config.pem_cert_chains);
-  if (c->config.pem_cert_chains_sizes != NULL) {
-    gpr_free(c->config.pem_cert_chains_sizes);
-  }
-  if (c->config.pem_root_certs != NULL) gpr_free(c->config.pem_root_certs);
-}
-
-static grpc_security_status ssl_create_security_connector(
-    grpc_channel_credentials *creds, grpc_call_credentials *call_creds,
-    const char *target, const grpc_channel_args *args,
-    grpc_channel_security_connector **sc, grpc_channel_args **new_args) {
-  grpc_ssl_credentials *c = (grpc_ssl_credentials *)creds;
-  grpc_security_status status = GRPC_SECURITY_OK;
-  size_t i = 0;
-  const char *overridden_target_name = NULL;
-  grpc_arg new_arg;
-
-  for (i = 0; args && i < args->num_args; i++) {
-    grpc_arg *arg = &args->args[i];
-    if (strcmp(arg->key, GRPC_SSL_TARGET_NAME_OVERRIDE_ARG) == 0 &&
-        arg->type == GRPC_ARG_STRING) {
-      overridden_target_name = arg->value.string;
-      break;
-    }
-  }
-  status = grpc_ssl_channel_security_connector_create(
-      call_creds, &c->config, target, overridden_target_name, sc);
-  if (status != GRPC_SECURITY_OK) {
-    return status;
-  }
-  new_arg.type = GRPC_ARG_STRING;
-  new_arg.key = GRPC_ARG_HTTP2_SCHEME;
-  new_arg.value.string = "https";
-  *new_args = grpc_channel_args_copy_and_add(args, &new_arg, 1);
-  return status;
-}
-
-static grpc_security_status ssl_server_create_security_connector(
-    grpc_server_credentials *creds, grpc_server_security_connector **sc) {
-  grpc_ssl_server_credentials *c = (grpc_ssl_server_credentials *)creds;
-  return grpc_ssl_server_security_connector_create(&c->config, sc);
-}
-
-static grpc_channel_credentials_vtable ssl_vtable = {
-    ssl_destruct, ssl_create_security_connector};
-
-static grpc_server_credentials_vtable ssl_server_vtable = {
-    ssl_server_destruct, ssl_server_create_security_connector};
-
-static void ssl_copy_key_material(const char *input, unsigned char **output,
-                                  size_t *output_size) {
-  *output_size = strlen(input);
-  *output = gpr_malloc(*output_size);
-  memcpy(*output, input, *output_size);
-}
-
-static void ssl_build_config(const char *pem_root_certs,
-                             grpc_ssl_pem_key_cert_pair *pem_key_cert_pair,
-                             grpc_ssl_config *config) {
-  if (pem_root_certs != NULL) {
-    ssl_copy_key_material(pem_root_certs, &config->pem_root_certs,
-                          &config->pem_root_certs_size);
-  }
-  if (pem_key_cert_pair != NULL) {
-    GPR_ASSERT(pem_key_cert_pair->private_key != NULL);
-    GPR_ASSERT(pem_key_cert_pair->cert_chain != NULL);
-    ssl_copy_key_material(pem_key_cert_pair->private_key,
-                          &config->pem_private_key,
-                          &config->pem_private_key_size);
-    ssl_copy_key_material(pem_key_cert_pair->cert_chain,
-                          &config->pem_cert_chain,
-                          &config->pem_cert_chain_size);
-  }
-}
-
-static void ssl_build_server_config(
-    const char *pem_root_certs, grpc_ssl_pem_key_cert_pair *pem_key_cert_pairs,
-    size_t num_key_cert_pairs,
-    grpc_ssl_client_certificate_request_type client_certificate_request,
-    grpc_ssl_server_config *config) {
-  size_t i;
-  config->client_certificate_request = client_certificate_request;
-  if (pem_root_certs != NULL) {
-    ssl_copy_key_material(pem_root_certs, &config->pem_root_certs,
-                          &config->pem_root_certs_size);
-  }
-  if (num_key_cert_pairs > 0) {
-    GPR_ASSERT(pem_key_cert_pairs != NULL);
-    config->pem_private_keys =
-        gpr_malloc(num_key_cert_pairs * sizeof(unsigned char *));
-    config->pem_cert_chains =
-        gpr_malloc(num_key_cert_pairs * sizeof(unsigned char *));
-    config->pem_private_keys_sizes =
-        gpr_malloc(num_key_cert_pairs * sizeof(size_t));
-    config->pem_cert_chains_sizes =
-        gpr_malloc(num_key_cert_pairs * sizeof(size_t));
-  }
-  config->num_key_cert_pairs = num_key_cert_pairs;
-  for (i = 0; i < num_key_cert_pairs; i++) {
-    GPR_ASSERT(pem_key_cert_pairs[i].private_key != NULL);
-    GPR_ASSERT(pem_key_cert_pairs[i].cert_chain != NULL);
-    ssl_copy_key_material(pem_key_cert_pairs[i].private_key,
-                          &config->pem_private_keys[i],
-                          &config->pem_private_keys_sizes[i]);
-    ssl_copy_key_material(pem_key_cert_pairs[i].cert_chain,
-                          &config->pem_cert_chains[i],
-                          &config->pem_cert_chains_sizes[i]);
-  }
-}
-
-grpc_channel_credentials *grpc_ssl_credentials_create(
-    const char *pem_root_certs, grpc_ssl_pem_key_cert_pair *pem_key_cert_pair,
-    void *reserved) {
-  grpc_ssl_credentials *c = gpr_malloc(sizeof(grpc_ssl_credentials));
-  GRPC_API_TRACE(
-      "grpc_ssl_credentials_create(pem_root_certs=%s, "
-      "pem_key_cert_pair=%p, "
-      "reserved=%p)",
-      3, (pem_root_certs, pem_key_cert_pair, reserved));
-  GPR_ASSERT(reserved == NULL);
-  memset(c, 0, sizeof(grpc_ssl_credentials));
-  c->base.type = GRPC_CHANNEL_CREDENTIALS_TYPE_SSL;
-  c->base.vtable = &ssl_vtable;
-  gpr_ref_init(&c->base.refcount, 1);
-  ssl_build_config(pem_root_certs, pem_key_cert_pair, &c->config);
-  return &c->base;
-}
-
-grpc_server_credentials *grpc_ssl_server_credentials_create(
-    const char *pem_root_certs, grpc_ssl_pem_key_cert_pair *pem_key_cert_pairs,
-    size_t num_key_cert_pairs, int force_client_auth, void *reserved) {
-  return grpc_ssl_server_credentials_create_ex(
-      pem_root_certs, pem_key_cert_pairs, num_key_cert_pairs,
-      force_client_auth
-          ? GRPC_SSL_REQUEST_AND_REQUIRE_CLIENT_CERTIFICATE_AND_VERIFY
-          : GRPC_SSL_DONT_REQUEST_CLIENT_CERTIFICATE,
-      reserved);
-}
-
-grpc_server_credentials *grpc_ssl_server_credentials_create_ex(
-    const char *pem_root_certs, grpc_ssl_pem_key_cert_pair *pem_key_cert_pairs,
-    size_t num_key_cert_pairs,
-    grpc_ssl_client_certificate_request_type client_certificate_request,
-    void *reserved) {
-  grpc_ssl_server_credentials *c =
-      gpr_malloc(sizeof(grpc_ssl_server_credentials));
-  GRPC_API_TRACE(
-      "grpc_ssl_server_credentials_create_ex("
-      "pem_root_certs=%s, pem_key_cert_pairs=%p, num_key_cert_pairs=%lu, "
-      "client_certificate_request=%d, reserved=%p)",
-      5, (pem_root_certs, pem_key_cert_pairs, (unsigned long)num_key_cert_pairs,
-          client_certificate_request, reserved));
-  GPR_ASSERT(reserved == NULL);
-  memset(c, 0, sizeof(grpc_ssl_server_credentials));
-  c->base.type = GRPC_CHANNEL_CREDENTIALS_TYPE_SSL;
-  gpr_ref_init(&c->base.refcount, 1);
-  c->base.vtable = &ssl_server_vtable;
-  ssl_build_server_config(pem_root_certs, pem_key_cert_pairs,
-                          num_key_cert_pairs, client_certificate_request,
-                          &c->config);
-  return &c->base;
-}
-
-/* -- Jwt credentials -- */
-
-static void jwt_reset_cache(grpc_service_account_jwt_access_credentials *c) {
-  if (c->cached.jwt_md != NULL) {
-    grpc_credentials_md_store_unref(c->cached.jwt_md);
-    c->cached.jwt_md = NULL;
-  }
-  if (c->cached.service_url != NULL) {
-    gpr_free(c->cached.service_url);
-    c->cached.service_url = NULL;
-  }
-  c->cached.jwt_expiration = gpr_inf_past(GPR_CLOCK_REALTIME);
-}
-
-static void jwt_destruct(grpc_call_credentials *creds) {
-  grpc_service_account_jwt_access_credentials *c =
-      (grpc_service_account_jwt_access_credentials *)creds;
-  grpc_auth_json_key_destruct(&c->key);
-  jwt_reset_cache(c);
-  gpr_mu_destroy(&c->cache_mu);
-}
-
-static void jwt_get_request_metadata(grpc_exec_ctx *exec_ctx,
-                                     grpc_call_credentials *creds,
-                                     grpc_pollset *pollset,
-                                     grpc_auth_metadata_context context,
-                                     grpc_credentials_metadata_cb cb,
-                                     void *user_data) {
-  grpc_service_account_jwt_access_credentials *c =
-      (grpc_service_account_jwt_access_credentials *)creds;
-  gpr_timespec refresh_threshold = gpr_time_from_seconds(
-      GRPC_SECURE_TOKEN_REFRESH_THRESHOLD_SECS, GPR_TIMESPAN);
-
-  /* See if we can return a cached jwt. */
-  grpc_credentials_md_store *jwt_md = NULL;
-  {
-    gpr_mu_lock(&c->cache_mu);
-    if (c->cached.service_url != NULL &&
-        strcmp(c->cached.service_url, context.service_url) == 0 &&
-        c->cached.jwt_md != NULL &&
-        (gpr_time_cmp(gpr_time_sub(c->cached.jwt_expiration,
-                                   gpr_now(GPR_CLOCK_REALTIME)),
-                      refresh_threshold) > 0)) {
-      jwt_md = grpc_credentials_md_store_ref(c->cached.jwt_md);
-    }
-    gpr_mu_unlock(&c->cache_mu);
-  }
-
-  if (jwt_md == NULL) {
-    char *jwt = NULL;
-    /* Generate a new jwt. */
-    gpr_mu_lock(&c->cache_mu);
-    jwt_reset_cache(c);
-    jwt = grpc_jwt_encode_and_sign(&c->key, context.service_url,
-                                   c->jwt_lifetime, NULL);
-    if (jwt != NULL) {
-      char *md_value;
-      gpr_asprintf(&md_value, "Bearer %s", jwt);
-      gpr_free(jwt);
-      c->cached.jwt_expiration =
-          gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), c->jwt_lifetime);
-      c->cached.service_url = gpr_strdup(context.service_url);
-      c->cached.jwt_md = grpc_credentials_md_store_create(1);
-      grpc_credentials_md_store_add_cstrings(
-          c->cached.jwt_md, GRPC_AUTHORIZATION_METADATA_KEY, md_value);
-      gpr_free(md_value);
-      jwt_md = grpc_credentials_md_store_ref(c->cached.jwt_md);
-    }
-    gpr_mu_unlock(&c->cache_mu);
-  }
-
-  if (jwt_md != NULL) {
-    cb(exec_ctx, user_data, jwt_md->entries, jwt_md->num_entries,
-       GRPC_CREDENTIALS_OK, NULL);
-    grpc_credentials_md_store_unref(jwt_md);
-  } else {
-    cb(exec_ctx, user_data, NULL, 0, GRPC_CREDENTIALS_ERROR, "");
-  }
-}
-
-static grpc_call_credentials_vtable jwt_vtable = {jwt_destruct,
-                                                  jwt_get_request_metadata};
-
-grpc_call_credentials *
-grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
-    grpc_auth_json_key key, gpr_timespec token_lifetime) {
-  grpc_service_account_jwt_access_credentials *c;
-  if (!grpc_auth_json_key_is_valid(&key)) {
-    gpr_log(GPR_ERROR, "Invalid input for jwt credentials creation");
-    return NULL;
-  }
-  c = gpr_malloc(sizeof(grpc_service_account_jwt_access_credentials));
-  memset(c, 0, sizeof(grpc_service_account_jwt_access_credentials));
-  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_JWT;
-  gpr_ref_init(&c->base.refcount, 1);
-  c->base.vtable = &jwt_vtable;
-  c->key = key;
-  c->jwt_lifetime = token_lifetime;
-  gpr_mu_init(&c->cache_mu);
-  jwt_reset_cache(c);
-  return &c->base;
-}
-
-grpc_call_credentials *grpc_service_account_jwt_access_credentials_create(
-    const char *json_key, gpr_timespec token_lifetime, void *reserved) {
-  GRPC_API_TRACE(
-      "grpc_service_account_jwt_access_credentials_create("
-      "json_key=%s, "
-      "token_lifetime="
-      "gpr_timespec { tv_sec: %lld, tv_nsec: %d, clock_type: %d }, "
-      "reserved=%p)",
-      5,
-      (json_key, (long long)token_lifetime.tv_sec, (int)token_lifetime.tv_nsec,
-       (int)token_lifetime.clock_type, reserved));
-  GPR_ASSERT(reserved == NULL);
-  return grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
-      grpc_auth_json_key_create_from_string(json_key), token_lifetime);
-}
-
-/* -- Oauth2TokenFetcher credentials -- */
-
-static void oauth2_token_fetcher_destruct(grpc_call_credentials *creds) {
-  grpc_oauth2_token_fetcher_credentials *c =
-      (grpc_oauth2_token_fetcher_credentials *)creds;
-  grpc_credentials_md_store_unref(c->access_token_md);
-  gpr_mu_destroy(&c->mu);
-  grpc_httpcli_context_destroy(&c->httpcli_context);
-}
-
-grpc_credentials_status
-grpc_oauth2_token_fetcher_credentials_parse_server_response(
-    const grpc_http_response *response, grpc_credentials_md_store **token_md,
-    gpr_timespec *token_lifetime) {
-  char *null_terminated_body = NULL;
-  char *new_access_token = NULL;
-  grpc_credentials_status status = GRPC_CREDENTIALS_OK;
-  grpc_json *json = NULL;
-
-  if (response == NULL) {
-    gpr_log(GPR_ERROR, "Received NULL response.");
-    status = GRPC_CREDENTIALS_ERROR;
-    goto end;
-  }
-
-  if (response->body_length > 0) {
-    null_terminated_body = gpr_malloc(response->body_length + 1);
-    null_terminated_body[response->body_length] = '\0';
-    memcpy(null_terminated_body, response->body, response->body_length);
-  }
-
-  if (response->status != 200) {
-    gpr_log(GPR_ERROR, "Call to http server ended with error %d [%s].",
-            response->status,
-            null_terminated_body != NULL ? null_terminated_body : "");
-    status = GRPC_CREDENTIALS_ERROR;
-    goto end;
-  } else {
-    grpc_json *access_token = NULL;
-    grpc_json *token_type = NULL;
-    grpc_json *expires_in = NULL;
-    grpc_json *ptr;
-    json = grpc_json_parse_string(null_terminated_body);
-    if (json == NULL) {
-      gpr_log(GPR_ERROR, "Could not parse JSON from %s", null_terminated_body);
-      status = GRPC_CREDENTIALS_ERROR;
-      goto end;
-    }
-    if (json->type != GRPC_JSON_OBJECT) {
-      gpr_log(GPR_ERROR, "Response should be a JSON object");
-      status = GRPC_CREDENTIALS_ERROR;
-      goto end;
-    }
-    for (ptr = json->child; ptr; ptr = ptr->next) {
-      if (strcmp(ptr->key, "access_token") == 0) {
-        access_token = ptr;
-      } else if (strcmp(ptr->key, "token_type") == 0) {
-        token_type = ptr;
-      } else if (strcmp(ptr->key, "expires_in") == 0) {
-        expires_in = ptr;
-      }
-    }
-    if (access_token == NULL || access_token->type != GRPC_JSON_STRING) {
-      gpr_log(GPR_ERROR, "Missing or invalid access_token in JSON.");
-      status = GRPC_CREDENTIALS_ERROR;
-      goto end;
-    }
-    if (token_type == NULL || token_type->type != GRPC_JSON_STRING) {
-      gpr_log(GPR_ERROR, "Missing or invalid token_type in JSON.");
-      status = GRPC_CREDENTIALS_ERROR;
-      goto end;
-    }
-    if (expires_in == NULL || expires_in->type != GRPC_JSON_NUMBER) {
-      gpr_log(GPR_ERROR, "Missing or invalid expires_in in JSON.");
-      status = GRPC_CREDENTIALS_ERROR;
-      goto end;
-    }
-    gpr_asprintf(&new_access_token, "%s %s", token_type->value,
-                 access_token->value);
-    token_lifetime->tv_sec = strtol(expires_in->value, NULL, 10);
-    token_lifetime->tv_nsec = 0;
-    token_lifetime->clock_type = GPR_TIMESPAN;
-    if (*token_md != NULL) grpc_credentials_md_store_unref(*token_md);
-    *token_md = grpc_credentials_md_store_create(1);
-    grpc_credentials_md_store_add_cstrings(
-        *token_md, GRPC_AUTHORIZATION_METADATA_KEY, new_access_token);
-    status = GRPC_CREDENTIALS_OK;
-  }
-
-end:
-  if (status != GRPC_CREDENTIALS_OK && (*token_md != NULL)) {
-    grpc_credentials_md_store_unref(*token_md);
-    *token_md = NULL;
-  }
-  if (null_terminated_body != NULL) gpr_free(null_terminated_body);
-  if (new_access_token != NULL) gpr_free(new_access_token);
-  if (json != NULL) grpc_json_destroy(json);
-  return status;
-}
-
-static void on_oauth2_token_fetcher_http_response(
-    grpc_exec_ctx *exec_ctx, void *user_data,
-    const grpc_http_response *response) {
-  grpc_credentials_metadata_request *r =
-      (grpc_credentials_metadata_request *)user_data;
-  grpc_oauth2_token_fetcher_credentials *c =
-      (grpc_oauth2_token_fetcher_credentials *)r->creds;
-  gpr_timespec token_lifetime;
-  grpc_credentials_status status;
-
-  gpr_mu_lock(&c->mu);
-  status = grpc_oauth2_token_fetcher_credentials_parse_server_response(
-      response, &c->access_token_md, &token_lifetime);
-  if (status == GRPC_CREDENTIALS_OK) {
-    c->token_expiration =
-        gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), token_lifetime);
-    r->cb(exec_ctx, r->user_data, c->access_token_md->entries,
-          c->access_token_md->num_entries, status, NULL);
-  } else {
-    c->token_expiration = gpr_inf_past(GPR_CLOCK_REALTIME);
-    r->cb(exec_ctx, r->user_data, NULL, 0, status, "");
-  }
-  gpr_mu_unlock(&c->mu);
-  grpc_credentials_metadata_request_destroy(r);
-}
-
-static void oauth2_token_fetcher_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_call_credentials *creds,
-    grpc_pollset *pollset, grpc_auth_metadata_context context,
-    grpc_credentials_metadata_cb cb, void *user_data) {
-  grpc_oauth2_token_fetcher_credentials *c =
-      (grpc_oauth2_token_fetcher_credentials *)creds;
-  gpr_timespec refresh_threshold = gpr_time_from_seconds(
-      GRPC_SECURE_TOKEN_REFRESH_THRESHOLD_SECS, GPR_TIMESPAN);
-  grpc_credentials_md_store *cached_access_token_md = NULL;
-  {
-    gpr_mu_lock(&c->mu);
-    if (c->access_token_md != NULL &&
-        (gpr_time_cmp(
-             gpr_time_sub(c->token_expiration, gpr_now(GPR_CLOCK_REALTIME)),
-             refresh_threshold) > 0)) {
-      cached_access_token_md =
-          grpc_credentials_md_store_ref(c->access_token_md);
-    }
-    gpr_mu_unlock(&c->mu);
-  }
-  if (cached_access_token_md != NULL) {
-    cb(exec_ctx, user_data, cached_access_token_md->entries,
-       cached_access_token_md->num_entries, GRPC_CREDENTIALS_OK, NULL);
-    grpc_credentials_md_store_unref(cached_access_token_md);
-  } else {
-    c->fetch_func(
-        exec_ctx,
-        grpc_credentials_metadata_request_create(creds, cb, user_data),
-        &c->httpcli_context, pollset, on_oauth2_token_fetcher_http_response,
-        gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), refresh_threshold));
-  }
-}
-
-static void init_oauth2_token_fetcher(grpc_oauth2_token_fetcher_credentials *c,
-                                      grpc_fetch_oauth2_func fetch_func) {
-  memset(c, 0, sizeof(grpc_oauth2_token_fetcher_credentials));
-  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_OAUTH2;
-  gpr_ref_init(&c->base.refcount, 1);
-  gpr_mu_init(&c->mu);
-  c->token_expiration = gpr_inf_past(GPR_CLOCK_REALTIME);
-  c->fetch_func = fetch_func;
-  grpc_httpcli_context_init(&c->httpcli_context);
-}
-
-/* -- GoogleComputeEngine credentials. -- */
-
-static grpc_call_credentials_vtable compute_engine_vtable = {
-    oauth2_token_fetcher_destruct, oauth2_token_fetcher_get_request_metadata};
-
-static void compute_engine_fetch_oauth2(
-    grpc_exec_ctx *exec_ctx, grpc_credentials_metadata_request *metadata_req,
-    grpc_httpcli_context *httpcli_context, grpc_pollset *pollset,
-    grpc_httpcli_response_cb response_cb, gpr_timespec deadline) {
-  grpc_http_header header = {"Metadata-Flavor", "Google"};
-  grpc_httpcli_request request;
-  memset(&request, 0, sizeof(grpc_httpcli_request));
-  request.host = GRPC_COMPUTE_ENGINE_METADATA_HOST;
-  request.http.path = GRPC_COMPUTE_ENGINE_METADATA_TOKEN_PATH;
-  request.http.hdr_count = 1;
-  request.http.hdrs = &header;
-  grpc_httpcli_get(exec_ctx, httpcli_context, pollset, &request, deadline,
-                   response_cb, metadata_req);
-}
-
-grpc_call_credentials *grpc_google_compute_engine_credentials_create(
-    void *reserved) {
-  grpc_oauth2_token_fetcher_credentials *c =
-      gpr_malloc(sizeof(grpc_oauth2_token_fetcher_credentials));
-  GRPC_API_TRACE("grpc_compute_engine_credentials_create(reserved=%p)", 1,
-                 (reserved));
-  GPR_ASSERT(reserved == NULL);
-  init_oauth2_token_fetcher(c, compute_engine_fetch_oauth2);
-  c->base.vtable = &compute_engine_vtable;
-  return &c->base;
-}
-
-/* -- GoogleRefreshToken credentials. -- */
-
-static void refresh_token_destruct(grpc_call_credentials *creds) {
-  grpc_google_refresh_token_credentials *c =
-      (grpc_google_refresh_token_credentials *)creds;
-  grpc_auth_refresh_token_destruct(&c->refresh_token);
-  oauth2_token_fetcher_destruct(&c->base.base);
-}
-
-static grpc_call_credentials_vtable refresh_token_vtable = {
-    refresh_token_destruct, oauth2_token_fetcher_get_request_metadata};
-
-static void refresh_token_fetch_oauth2(
-    grpc_exec_ctx *exec_ctx, grpc_credentials_metadata_request *metadata_req,
-    grpc_httpcli_context *httpcli_context, grpc_pollset *pollset,
-    grpc_httpcli_response_cb response_cb, gpr_timespec deadline) {
-  grpc_google_refresh_token_credentials *c =
-      (grpc_google_refresh_token_credentials *)metadata_req->creds;
-  grpc_http_header header = {"Content-Type",
-                             "application/x-www-form-urlencoded"};
-  grpc_httpcli_request request;
-  char *body = NULL;
-  gpr_asprintf(&body, GRPC_REFRESH_TOKEN_POST_BODY_FORMAT_STRING,
-               c->refresh_token.client_id, c->refresh_token.client_secret,
-               c->refresh_token.refresh_token);
-  memset(&request, 0, sizeof(grpc_httpcli_request));
-  request.host = GRPC_GOOGLE_OAUTH2_SERVICE_HOST;
-  request.http.path = GRPC_GOOGLE_OAUTH2_SERVICE_TOKEN_PATH;
-  request.http.hdr_count = 1;
-  request.http.hdrs = &header;
-  request.handshaker = &grpc_httpcli_ssl;
-  grpc_httpcli_post(exec_ctx, httpcli_context, pollset, &request, body,
-                    strlen(body), deadline, response_cb, metadata_req);
-  gpr_free(body);
-}
-
-grpc_call_credentials *
-grpc_refresh_token_credentials_create_from_auth_refresh_token(
-    grpc_auth_refresh_token refresh_token) {
-  grpc_google_refresh_token_credentials *c;
-  if (!grpc_auth_refresh_token_is_valid(&refresh_token)) {
-    gpr_log(GPR_ERROR, "Invalid input for refresh token credentials creation");
-    return NULL;
-  }
-  c = gpr_malloc(sizeof(grpc_google_refresh_token_credentials));
-  memset(c, 0, sizeof(grpc_google_refresh_token_credentials));
-  init_oauth2_token_fetcher(&c->base, refresh_token_fetch_oauth2);
-  c->base.base.vtable = &refresh_token_vtable;
-  c->refresh_token = refresh_token;
-  return &c->base.base;
-}
-
-grpc_call_credentials *grpc_google_refresh_token_credentials_create(
-    const char *json_refresh_token, void *reserved) {
-  GRPC_API_TRACE(
-      "grpc_refresh_token_credentials_create(json_refresh_token=%s, "
-      "reserved=%p)",
-      2, (json_refresh_token, reserved));
-  GPR_ASSERT(reserved == NULL);
-  return grpc_refresh_token_credentials_create_from_auth_refresh_token(
-      grpc_auth_refresh_token_create_from_string(json_refresh_token));
-}
-
-/* -- Metadata-only credentials. -- */
-
-static void md_only_test_destruct(grpc_call_credentials *creds) {
-  grpc_md_only_test_credentials *c = (grpc_md_only_test_credentials *)creds;
-  grpc_credentials_md_store_unref(c->md_store);
-}
-
-static void on_simulated_token_fetch_done(grpc_exec_ctx *exec_ctx,
-                                          void *user_data, bool success) {
-  grpc_credentials_metadata_request *r =
-      (grpc_credentials_metadata_request *)user_data;
-  grpc_md_only_test_credentials *c = (grpc_md_only_test_credentials *)r->creds;
-  r->cb(exec_ctx, r->user_data, c->md_store->entries, c->md_store->num_entries,
-        GRPC_CREDENTIALS_OK, NULL);
-  grpc_credentials_metadata_request_destroy(r);
-}
-
-static void md_only_test_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_call_credentials *creds,
-    grpc_pollset *pollset, grpc_auth_metadata_context context,
-    grpc_credentials_metadata_cb cb, void *user_data) {
-  grpc_md_only_test_credentials *c = (grpc_md_only_test_credentials *)creds;
-
-  if (c->is_async) {
-    grpc_credentials_metadata_request *cb_arg =
-        grpc_credentials_metadata_request_create(creds, cb, user_data);
-    grpc_executor_enqueue(
-        grpc_closure_create(on_simulated_token_fetch_done, cb_arg), true);
-  } else {
-    cb(exec_ctx, user_data, c->md_store->entries, 1, GRPC_CREDENTIALS_OK, NULL);
-  }
-}
-
-static grpc_call_credentials_vtable md_only_test_vtable = {
-    md_only_test_destruct, md_only_test_get_request_metadata};
-
-grpc_call_credentials *grpc_md_only_test_credentials_create(
-    const char *md_key, const char *md_value, int is_async) {
-  grpc_md_only_test_credentials *c =
-      gpr_malloc(sizeof(grpc_md_only_test_credentials));
-  memset(c, 0, sizeof(grpc_md_only_test_credentials));
-  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_OAUTH2;
-  c->base.vtable = &md_only_test_vtable;
-  gpr_ref_init(&c->base.refcount, 1);
-  c->md_store = grpc_credentials_md_store_create(1);
-  grpc_credentials_md_store_add_cstrings(c->md_store, md_key, md_value);
-  c->is_async = is_async;
-  return &c->base;
-}
-
-/* -- Oauth2 Access Token credentials. -- */
-
-static void access_token_destruct(grpc_call_credentials *creds) {
-  grpc_access_token_credentials *c = (grpc_access_token_credentials *)creds;
-  grpc_credentials_md_store_unref(c->access_token_md);
-}
-
-static void access_token_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_call_credentials *creds,
-    grpc_pollset *pollset, grpc_auth_metadata_context context,
-    grpc_credentials_metadata_cb cb, void *user_data) {
-  grpc_access_token_credentials *c = (grpc_access_token_credentials *)creds;
-  cb(exec_ctx, user_data, c->access_token_md->entries, 1, GRPC_CREDENTIALS_OK,
-     NULL);
-}
-
-static grpc_call_credentials_vtable access_token_vtable = {
-    access_token_destruct, access_token_get_request_metadata};
-
-grpc_call_credentials *grpc_access_token_credentials_create(
-    const char *access_token, void *reserved) {
-  grpc_access_token_credentials *c =
-      gpr_malloc(sizeof(grpc_access_token_credentials));
-  char *token_md_value;
-  GRPC_API_TRACE(
-      "grpc_access_token_credentials_create(access_token=%s, "
-      "reserved=%p)",
-      2, (access_token, reserved));
-  GPR_ASSERT(reserved == NULL);
-  memset(c, 0, sizeof(grpc_access_token_credentials));
-  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_OAUTH2;
-  c->base.vtable = &access_token_vtable;
-  gpr_ref_init(&c->base.refcount, 1);
-  c->access_token_md = grpc_credentials_md_store_create(1);
-  gpr_asprintf(&token_md_value, "Bearer %s", access_token);
-  grpc_credentials_md_store_add_cstrings(
-      c->access_token_md, GRPC_AUTHORIZATION_METADATA_KEY, token_md_value);
-  gpr_free(token_md_value);
-  return &c->base;
-}
-
-/* -- Fake transport security credentials. -- */
-
-static grpc_security_status fake_transport_security_create_security_connector(
-    grpc_channel_credentials *c, grpc_call_credentials *call_creds,
-    const char *target, const grpc_channel_args *args,
-    grpc_channel_security_connector **sc, grpc_channel_args **new_args) {
-  *sc = grpc_fake_channel_security_connector_create(call_creds);
-  return GRPC_SECURITY_OK;
-}
-
-static grpc_security_status
-fake_transport_security_server_create_security_connector(
-    grpc_server_credentials *c, grpc_server_security_connector **sc) {
-  *sc = grpc_fake_server_security_connector_create();
-  return GRPC_SECURITY_OK;
-}
-
-static grpc_channel_credentials_vtable
-    fake_transport_security_credentials_vtable = {
-        NULL, fake_transport_security_create_security_connector};
-
-static grpc_server_credentials_vtable
-    fake_transport_security_server_credentials_vtable = {
-        NULL, fake_transport_security_server_create_security_connector};
-
-grpc_channel_credentials *grpc_fake_transport_security_credentials_create(
-    void) {
-  grpc_channel_credentials *c = gpr_malloc(sizeof(grpc_channel_credentials));
-  memset(c, 0, sizeof(grpc_channel_credentials));
-  c->type = GRPC_CHANNEL_CREDENTIALS_TYPE_FAKE_TRANSPORT_SECURITY;
-  c->vtable = &fake_transport_security_credentials_vtable;
-  gpr_ref_init(&c->refcount, 1);
-  return c;
-}
-
-grpc_server_credentials *grpc_fake_transport_security_server_credentials_create(
-    void) {
-  grpc_server_credentials *c = gpr_malloc(sizeof(grpc_server_credentials));
-  memset(c, 0, sizeof(grpc_server_credentials));
-  c->type = GRPC_CHANNEL_CREDENTIALS_TYPE_FAKE_TRANSPORT_SECURITY;
-  gpr_ref_init(&c->refcount, 1);
-  c->vtable = &fake_transport_security_server_credentials_vtable;
-  return c;
-}
-
-/* -- Composite call credentials. -- */
-
-typedef struct {
-  grpc_composite_call_credentials *composite_creds;
-  size_t creds_index;
-  grpc_credentials_md_store *md_elems;
-  grpc_auth_metadata_context auth_md_context;
-  void *user_data;
-  grpc_pollset *pollset;
-  grpc_credentials_metadata_cb cb;
-} grpc_composite_call_credentials_metadata_context;
-
-static void composite_call_destruct(grpc_call_credentials *creds) {
-  grpc_composite_call_credentials *c = (grpc_composite_call_credentials *)creds;
-  size_t i;
-  for (i = 0; i < c->inner.num_creds; i++) {
-    grpc_call_credentials_unref(c->inner.creds_array[i]);
-  }
-  gpr_free(c->inner.creds_array);
-}
-
-static void composite_call_md_context_destroy(
-    grpc_composite_call_credentials_metadata_context *ctx) {
-  grpc_credentials_md_store_unref(ctx->md_elems);
-  gpr_free(ctx);
-}
-
-static void composite_call_metadata_cb(grpc_exec_ctx *exec_ctx, void *user_data,
-                                       grpc_credentials_md *md_elems,
-                                       size_t num_md,
-                                       grpc_credentials_status status,
-                                       const char *error_details) {
-  grpc_composite_call_credentials_metadata_context *ctx =
-      (grpc_composite_call_credentials_metadata_context *)user_data;
-  if (status != GRPC_CREDENTIALS_OK) {
-    ctx->cb(exec_ctx, ctx->user_data, NULL, 0, status, NULL);
-    return;
-  }
-
-  /* Copy the metadata in the context. */
-  if (num_md > 0) {
-    size_t i;
-    for (i = 0; i < num_md; i++) {
-      grpc_credentials_md_store_add(ctx->md_elems, md_elems[i].key,
-                                    md_elems[i].value);
-    }
-  }
-
-  /* See if we need to get some more metadata. */
-  if (ctx->creds_index < ctx->composite_creds->inner.num_creds) {
-    grpc_call_credentials *inner_creds =
-        ctx->composite_creds->inner.creds_array[ctx->creds_index++];
-    grpc_call_credentials_get_request_metadata(
-        exec_ctx, inner_creds, ctx->pollset, ctx->auth_md_context,
-        composite_call_metadata_cb, ctx);
-    return;
-  }
-
-  /* We're done!. */
-  ctx->cb(exec_ctx, ctx->user_data, ctx->md_elems->entries,
-          ctx->md_elems->num_entries, GRPC_CREDENTIALS_OK, NULL);
-  composite_call_md_context_destroy(ctx);
-}
-
-static void composite_call_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_call_credentials *creds,
-    grpc_pollset *pollset, grpc_auth_metadata_context auth_md_context,
-    grpc_credentials_metadata_cb cb, void *user_data) {
-  grpc_composite_call_credentials *c = (grpc_composite_call_credentials *)creds;
-  grpc_composite_call_credentials_metadata_context *ctx;
-
-  ctx = gpr_malloc(sizeof(grpc_composite_call_credentials_metadata_context));
-  memset(ctx, 0, sizeof(grpc_composite_call_credentials_metadata_context));
-  ctx->auth_md_context = auth_md_context;
-  ctx->user_data = user_data;
-  ctx->cb = cb;
-  ctx->composite_creds = c;
-  ctx->pollset = pollset;
-  ctx->md_elems = grpc_credentials_md_store_create(c->inner.num_creds);
-  grpc_call_credentials_get_request_metadata(
-      exec_ctx, c->inner.creds_array[ctx->creds_index++], pollset,
-      auth_md_context, composite_call_metadata_cb, ctx);
-}
-
-static grpc_call_credentials_vtable composite_call_credentials_vtable = {
-    composite_call_destruct, composite_call_get_request_metadata};
-
-static grpc_call_credentials_array get_creds_array(
-    grpc_call_credentials **creds_addr) {
-  grpc_call_credentials_array result;
-  grpc_call_credentials *creds = *creds_addr;
-  result.creds_array = creds_addr;
-  result.num_creds = 1;
-  if (strcmp(creds->type, GRPC_CALL_CREDENTIALS_TYPE_COMPOSITE) == 0) {
-    result = *grpc_composite_call_credentials_get_credentials(creds);
-  }
-  return result;
-}
-
-grpc_call_credentials *grpc_composite_call_credentials_create(
-    grpc_call_credentials *creds1, grpc_call_credentials *creds2,
-    void *reserved) {
-  size_t i;
-  size_t creds_array_byte_size;
-  grpc_call_credentials_array creds1_array;
-  grpc_call_credentials_array creds2_array;
-  grpc_composite_call_credentials *c;
-  GRPC_API_TRACE(
-      "grpc_composite_call_credentials_create(creds1=%p, creds2=%p, "
-      "reserved=%p)",
-      3, (creds1, creds2, reserved));
-  GPR_ASSERT(reserved == NULL);
-  GPR_ASSERT(creds1 != NULL);
-  GPR_ASSERT(creds2 != NULL);
-  c = gpr_malloc(sizeof(grpc_composite_call_credentials));
-  memset(c, 0, sizeof(grpc_composite_call_credentials));
-  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_COMPOSITE;
-  c->base.vtable = &composite_call_credentials_vtable;
-  gpr_ref_init(&c->base.refcount, 1);
-  creds1_array = get_creds_array(&creds1);
-  creds2_array = get_creds_array(&creds2);
-  c->inner.num_creds = creds1_array.num_creds + creds2_array.num_creds;
-  creds_array_byte_size = c->inner.num_creds * sizeof(grpc_call_credentials *);
-  c->inner.creds_array = gpr_malloc(creds_array_byte_size);
-  memset(c->inner.creds_array, 0, creds_array_byte_size);
-  for (i = 0; i < creds1_array.num_creds; i++) {
-    grpc_call_credentials *cur_creds = creds1_array.creds_array[i];
-    c->inner.creds_array[i] = grpc_call_credentials_ref(cur_creds);
-  }
-  for (i = 0; i < creds2_array.num_creds; i++) {
-    grpc_call_credentials *cur_creds = creds2_array.creds_array[i];
-    c->inner.creds_array[i + creds1_array.num_creds] =
-        grpc_call_credentials_ref(cur_creds);
-  }
-  return &c->base;
-}
-
-const grpc_call_credentials_array *
-grpc_composite_call_credentials_get_credentials(grpc_call_credentials *creds) {
-  const grpc_composite_call_credentials *c =
-      (const grpc_composite_call_credentials *)creds;
-  GPR_ASSERT(strcmp(creds->type, GRPC_CALL_CREDENTIALS_TYPE_COMPOSITE) == 0);
-  return &c->inner;
-}
-
-grpc_call_credentials *grpc_credentials_contains_type(
-    grpc_call_credentials *creds, const char *type,
-    grpc_call_credentials **composite_creds) {
-  size_t i;
-  if (strcmp(creds->type, type) == 0) {
-    if (composite_creds != NULL) *composite_creds = NULL;
-    return creds;
-  } else if (strcmp(creds->type, GRPC_CALL_CREDENTIALS_TYPE_COMPOSITE) == 0) {
-    const grpc_call_credentials_array *inner_creds_array =
-        grpc_composite_call_credentials_get_credentials(creds);
-    for (i = 0; i < inner_creds_array->num_creds; i++) {
-      if (strcmp(type, inner_creds_array->creds_array[i]->type) == 0) {
-        if (composite_creds != NULL) *composite_creds = creds;
-        return inner_creds_array->creds_array[i];
-      }
-    }
-  }
-  return NULL;
-}
-
-/* -- IAM credentials. -- */
-
-static void iam_destruct(grpc_call_credentials *creds) {
-  grpc_google_iam_credentials *c = (grpc_google_iam_credentials *)creds;
-  grpc_credentials_md_store_unref(c->iam_md);
-}
-
-static void iam_get_request_metadata(grpc_exec_ctx *exec_ctx,
-                                     grpc_call_credentials *creds,
-                                     grpc_pollset *pollset,
-                                     grpc_auth_metadata_context context,
-                                     grpc_credentials_metadata_cb cb,
-                                     void *user_data) {
-  grpc_google_iam_credentials *c = (grpc_google_iam_credentials *)creds;
-  cb(exec_ctx, user_data, c->iam_md->entries, c->iam_md->num_entries,
-     GRPC_CREDENTIALS_OK, NULL);
-}
-
-static grpc_call_credentials_vtable iam_vtable = {iam_destruct,
-                                                  iam_get_request_metadata};
-
-grpc_call_credentials *grpc_google_iam_credentials_create(
-    const char *token, const char *authority_selector, void *reserved) {
-  grpc_google_iam_credentials *c;
-  GRPC_API_TRACE(
-      "grpc_iam_credentials_create(token=%s, authority_selector=%s, "
-      "reserved=%p)",
-      3, (token, authority_selector, reserved));
-  GPR_ASSERT(reserved == NULL);
-  GPR_ASSERT(token != NULL);
-  GPR_ASSERT(authority_selector != NULL);
-  c = gpr_malloc(sizeof(grpc_google_iam_credentials));
-  memset(c, 0, sizeof(grpc_google_iam_credentials));
-  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_IAM;
-  c->base.vtable = &iam_vtable;
-  gpr_ref_init(&c->base.refcount, 1);
-  c->iam_md = grpc_credentials_md_store_create(2);
-  grpc_credentials_md_store_add_cstrings(
-      c->iam_md, GRPC_IAM_AUTHORIZATION_TOKEN_METADATA_KEY, token);
-  grpc_credentials_md_store_add_cstrings(
-      c->iam_md, GRPC_IAM_AUTHORITY_SELECTOR_METADATA_KEY, authority_selector);
-  return &c->base;
-}
-
-/* -- Plugin credentials. -- */
-
-typedef struct {
-  void *user_data;
-  grpc_credentials_metadata_cb cb;
-} grpc_metadata_plugin_request;
-
-static void plugin_destruct(grpc_call_credentials *creds) {
-  grpc_plugin_credentials *c = (grpc_plugin_credentials *)creds;
-  if (c->plugin.state != NULL && c->plugin.destroy != NULL) {
-    c->plugin.destroy(c->plugin.state);
-  }
-}
-
-static void plugin_md_request_metadata_ready(void *request,
-                                             const grpc_metadata *md,
-                                             size_t num_md,
-                                             grpc_status_code status,
-                                             const char *error_details) {
-  /* called from application code */
-  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
-  grpc_metadata_plugin_request *r = (grpc_metadata_plugin_request *)request;
-  if (status != GRPC_STATUS_OK) {
-    if (error_details != NULL) {
-      gpr_log(GPR_ERROR, "Getting metadata from plugin failed with error: %s",
-              error_details);
-    }
-    r->cb(&exec_ctx, r->user_data, NULL, 0, GRPC_CREDENTIALS_ERROR,
-          error_details);
-  } else {
-    size_t i;
-    grpc_credentials_md *md_array = NULL;
-    if (num_md > 0) {
-      md_array = gpr_malloc(num_md * sizeof(grpc_credentials_md));
-      for (i = 0; i < num_md; i++) {
-        md_array[i].key = gpr_slice_from_copied_string(md[i].key);
-        md_array[i].value =
-            gpr_slice_from_copied_buffer(md[i].value, md[i].value_length);
-      }
-    }
-    r->cb(&exec_ctx, r->user_data, md_array, num_md, GRPC_CREDENTIALS_OK, NULL);
-    if (md_array != NULL) {
-      for (i = 0; i < num_md; i++) {
-        gpr_slice_unref(md_array[i].key);
-        gpr_slice_unref(md_array[i].value);
-      }
-      gpr_free(md_array);
-    }
-  }
-  gpr_free(r);
-  grpc_exec_ctx_finish(&exec_ctx);
-}
-
-static void plugin_get_request_metadata(grpc_exec_ctx *exec_ctx,
-                                        grpc_call_credentials *creds,
-                                        grpc_pollset *pollset,
-                                        grpc_auth_metadata_context context,
-                                        grpc_credentials_metadata_cb cb,
-                                        void *user_data) {
-  grpc_plugin_credentials *c = (grpc_plugin_credentials *)creds;
-  if (c->plugin.get_metadata != NULL) {
-    grpc_metadata_plugin_request *request = gpr_malloc(sizeof(*request));
-    memset(request, 0, sizeof(*request));
-    request->user_data = user_data;
-    request->cb = cb;
-    c->plugin.get_metadata(c->plugin.state, context,
-                           plugin_md_request_metadata_ready, request);
-  } else {
-    cb(exec_ctx, user_data, NULL, 0, GRPC_CREDENTIALS_OK, NULL);
-  }
-}
-
-static grpc_call_credentials_vtable plugin_vtable = {
-    plugin_destruct, plugin_get_request_metadata};
-
-grpc_call_credentials *grpc_metadata_credentials_create_from_plugin(
-    grpc_metadata_credentials_plugin plugin, void *reserved) {
-  grpc_plugin_credentials *c = gpr_malloc(sizeof(*c));
-  GRPC_API_TRACE("grpc_metadata_credentials_create_from_plugin(reserved=%p)", 1,
-                 (reserved));
-  GPR_ASSERT(reserved == NULL);
-  memset(c, 0, sizeof(*c));
-  c->base.type = plugin.type;
-  c->base.vtable = &plugin_vtable;
-  gpr_ref_init(&c->base.refcount, 1);
-  c->plugin = plugin;
-  return &c->base;
-}
-
-/* -- Composite channel credentials. -- */
-
-static void composite_channel_destruct(grpc_channel_credentials *creds) {
-  grpc_composite_channel_credentials *c =
-      (grpc_composite_channel_credentials *)creds;
-  grpc_channel_credentials_unref(c->inner_creds);
-  grpc_call_credentials_unref(c->call_creds);
-}
-
-static grpc_security_status composite_channel_create_security_connector(
-    grpc_channel_credentials *creds, grpc_call_credentials *call_creds,
-    const char *target, const grpc_channel_args *args,
-    grpc_channel_security_connector **sc, grpc_channel_args **new_args) {
-  grpc_composite_channel_credentials *c =
-      (grpc_composite_channel_credentials *)creds;
-  grpc_security_status status = GRPC_SECURITY_ERROR;
-
-  GPR_ASSERT(c->inner_creds != NULL && c->call_creds != NULL &&
-             c->inner_creds->vtable != NULL &&
-             c->inner_creds->vtable->create_security_connector != NULL);
-  /* If we are passed a call_creds, create a call composite to pass it
-     downstream. */
-  if (call_creds != NULL) {
-    grpc_call_credentials *composite_call_creds =
-        grpc_composite_call_credentials_create(c->call_creds, call_creds, NULL);
-    status = c->inner_creds->vtable->create_security_connector(
-        c->inner_creds, composite_call_creds, target, args, sc, new_args);
-    grpc_call_credentials_unref(composite_call_creds);
-  } else {
-    status = c->inner_creds->vtable->create_security_connector(
-        c->inner_creds, c->call_creds, target, args, sc, new_args);
-  }
-  return status;
-}
-
-static grpc_channel_credentials_vtable composite_channel_credentials_vtable = {
-    composite_channel_destruct, composite_channel_create_security_connector};
-
-grpc_channel_credentials *grpc_composite_channel_credentials_create(
-    grpc_channel_credentials *channel_creds, grpc_call_credentials *call_creds,
-    void *reserved) {
-  grpc_composite_channel_credentials *c = gpr_malloc(sizeof(*c));
-  memset(c, 0, sizeof(*c));
-  GPR_ASSERT(channel_creds != NULL && call_creds != NULL && reserved == NULL);
-  GRPC_API_TRACE(
-      "grpc_composite_channel_credentials_create(channel_creds=%p, "
-      "call_creds=%p, reserved=%p)",
-      3, (channel_creds, call_creds, reserved));
-  c->base.type = channel_creds->type;
-  c->base.vtable = &composite_channel_credentials_vtable;
-  gpr_ref_init(&c->base.refcount, 1);
-  c->inner_creds = grpc_channel_credentials_ref(channel_creds);
-  c->call_creds = grpc_call_credentials_ref(call_creds);
-  return &c->base;
-}
diff --git a/src/core/lib/security/credentials/composite/composite_credentials.c b/src/core/lib/security/credentials/composite/composite_credentials.c
new file mode 100644
index 0000000000..53dbce1e1e
--- /dev/null
+++ b/src/core/lib/security/credentials/composite/composite_credentials.c
@@ -0,0 +1,263 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/lib/security/credentials/composite/composite_credentials.h"
+
+#include <string.h>
+
+#include "src/core/lib/surface/api_trace.h"
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+
+/* -- Composite call credentials. -- */
+
+typedef struct {
+  grpc_composite_call_credentials *composite_creds;
+  size_t creds_index;
+  grpc_credentials_md_store *md_elems;
+  grpc_auth_metadata_context auth_md_context;
+  void *user_data;
+  grpc_pollset *pollset;
+  grpc_credentials_metadata_cb cb;
+} grpc_composite_call_credentials_metadata_context;
+
+static void composite_call_destruct(grpc_call_credentials *creds) {
+  grpc_composite_call_credentials *c = (grpc_composite_call_credentials *)creds;
+  size_t i;
+  for (i = 0; i < c->inner.num_creds; i++) {
+    grpc_call_credentials_unref(c->inner.creds_array[i]);
+  }
+  gpr_free(c->inner.creds_array);
+}
+
+static void composite_call_md_context_destroy(
+    grpc_composite_call_credentials_metadata_context *ctx) {
+  grpc_credentials_md_store_unref(ctx->md_elems);
+  gpr_free(ctx);
+}
+
+static void composite_call_metadata_cb(grpc_exec_ctx *exec_ctx, void *user_data,
+                                       grpc_credentials_md *md_elems,
+                                       size_t num_md,
+                                       grpc_credentials_status status,
+                                       const char *error_details) {
+  grpc_composite_call_credentials_metadata_context *ctx =
+      (grpc_composite_call_credentials_metadata_context *)user_data;
+  if (status != GRPC_CREDENTIALS_OK) {
+    ctx->cb(exec_ctx, ctx->user_data, NULL, 0, status, error_details);
+    return;
+  }
+
+  /* Copy the metadata in the context. */
+  if (num_md > 0) {
+    size_t i;
+    for (i = 0; i < num_md; i++) {
+      grpc_credentials_md_store_add(ctx->md_elems, md_elems[i].key,
+                                    md_elems[i].value);
+    }
+  }
+
+  /* See if we need to get some more metadata. */
+  if (ctx->creds_index < ctx->composite_creds->inner.num_creds) {
+    grpc_call_credentials *inner_creds =
+        ctx->composite_creds->inner.creds_array[ctx->creds_index++];
+    grpc_call_credentials_get_request_metadata(
+        exec_ctx, inner_creds, ctx->pollset, ctx->auth_md_context,
+        composite_call_metadata_cb, ctx);
+    return;
+  }
+
+  /* We're done!. */
+  ctx->cb(exec_ctx, ctx->user_data, ctx->md_elems->entries,
+          ctx->md_elems->num_entries, GRPC_CREDENTIALS_OK, NULL);
+  composite_call_md_context_destroy(ctx);
+}
+
+static void composite_call_get_request_metadata(
+    grpc_exec_ctx *exec_ctx, grpc_call_credentials *creds,
+    grpc_pollset *pollset, grpc_auth_metadata_context auth_md_context,
+    grpc_credentials_metadata_cb cb, void *user_data) {
+  grpc_composite_call_credentials *c = (grpc_composite_call_credentials *)creds;
+  grpc_composite_call_credentials_metadata_context *ctx;
+
+  ctx = gpr_malloc(sizeof(grpc_composite_call_credentials_metadata_context));
+  memset(ctx, 0, sizeof(grpc_composite_call_credentials_metadata_context));
+  ctx->auth_md_context = auth_md_context;
+  ctx->user_data = user_data;
+  ctx->cb = cb;
+  ctx->composite_creds = c;
+  ctx->pollset = pollset;
+  ctx->md_elems = grpc_credentials_md_store_create(c->inner.num_creds);
+  grpc_call_credentials_get_request_metadata(
+      exec_ctx, c->inner.creds_array[ctx->creds_index++], pollset,
+      auth_md_context, composite_call_metadata_cb, ctx);
+}
+
+static grpc_call_credentials_vtable composite_call_credentials_vtable = {
+    composite_call_destruct, composite_call_get_request_metadata};
+
+static grpc_call_credentials_array get_creds_array(
+    grpc_call_credentials **creds_addr) {
+  grpc_call_credentials_array result;
+  grpc_call_credentials *creds = *creds_addr;
+  result.creds_array = creds_addr;
+  result.num_creds = 1;
+  if (strcmp(creds->type, GRPC_CALL_CREDENTIALS_TYPE_COMPOSITE) == 0) {
+    result = *grpc_composite_call_credentials_get_credentials(creds);
+  }
+  return result;
+}
+
+grpc_call_credentials *grpc_composite_call_credentials_create(
+    grpc_call_credentials *creds1, grpc_call_credentials *creds2,
+    void *reserved) {
+  size_t i;
+  size_t creds_array_byte_size;
+  grpc_call_credentials_array creds1_array;
+  grpc_call_credentials_array creds2_array;
+  grpc_composite_call_credentials *c;
+  GRPC_API_TRACE(
+      "grpc_composite_call_credentials_create(creds1=%p, creds2=%p, "
+      "reserved=%p)",
+      3, (creds1, creds2, reserved));
+  GPR_ASSERT(reserved == NULL);
+  GPR_ASSERT(creds1 != NULL);
+  GPR_ASSERT(creds2 != NULL);
+  c = gpr_malloc(sizeof(grpc_composite_call_credentials));
+  memset(c, 0, sizeof(grpc_composite_call_credentials));
+  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_COMPOSITE;
+  c->base.vtable = &composite_call_credentials_vtable;
+  gpr_ref_init(&c->base.refcount, 1);
+  creds1_array = get_creds_array(&creds1);
+  creds2_array = get_creds_array(&creds2);
+  c->inner.num_creds = creds1_array.num_creds + creds2_array.num_creds;
+  creds_array_byte_size = c->inner.num_creds * sizeof(grpc_call_credentials *);
+  c->inner.creds_array = gpr_malloc(creds_array_byte_size);
+  memset(c->inner.creds_array, 0, creds_array_byte_size);
+  for (i = 0; i < creds1_array.num_creds; i++) {
+    grpc_call_credentials *cur_creds = creds1_array.creds_array[i];
+    c->inner.creds_array[i] = grpc_call_credentials_ref(cur_creds);
+  }
+  for (i = 0; i < creds2_array.num_creds; i++) {
+    grpc_call_credentials *cur_creds = creds2_array.creds_array[i];
+    c->inner.creds_array[i + creds1_array.num_creds] =
+        grpc_call_credentials_ref(cur_creds);
+  }
+  return &c->base;
+}
+
+const grpc_call_credentials_array *
+grpc_composite_call_credentials_get_credentials(grpc_call_credentials *creds) {
+  const grpc_composite_call_credentials *c =
+      (const grpc_composite_call_credentials *)creds;
+  GPR_ASSERT(strcmp(creds->type, GRPC_CALL_CREDENTIALS_TYPE_COMPOSITE) == 0);
+  return &c->inner;
+}
+
+grpc_call_credentials *grpc_credentials_contains_type(
+    grpc_call_credentials *creds, const char *type,
+    grpc_call_credentials **composite_creds) {
+  size_t i;
+  if (strcmp(creds->type, type) == 0) {
+    if (composite_creds != NULL) *composite_creds = NULL;
+    return creds;
+  } else if (strcmp(creds->type, GRPC_CALL_CREDENTIALS_TYPE_COMPOSITE) == 0) {
+    const grpc_call_credentials_array *inner_creds_array =
+        grpc_composite_call_credentials_get_credentials(creds);
+    for (i = 0; i < inner_creds_array->num_creds; i++) {
+      if (strcmp(type, inner_creds_array->creds_array[i]->type) == 0) {
+        if (composite_creds != NULL) *composite_creds = creds;
+        return inner_creds_array->creds_array[i];
+      }
+    }
+  }
+  return NULL;
+}
+
+/* -- Composite channel credentials. -- */
+
+static void composite_channel_destruct(grpc_channel_credentials *creds) {
+  grpc_composite_channel_credentials *c =
+      (grpc_composite_channel_credentials *)creds;
+  grpc_channel_credentials_unref(c->inner_creds);
+  grpc_call_credentials_unref(c->call_creds);
+}
+
+static grpc_security_status composite_channel_create_security_connector(
+    grpc_channel_credentials *creds, grpc_call_credentials *call_creds,
+    const char *target, const grpc_channel_args *args,
+    grpc_channel_security_connector **sc, grpc_channel_args **new_args) {
+  grpc_composite_channel_credentials *c =
+      (grpc_composite_channel_credentials *)creds;
+  grpc_security_status status = GRPC_SECURITY_ERROR;
+
+  GPR_ASSERT(c->inner_creds != NULL && c->call_creds != NULL &&
+             c->inner_creds->vtable != NULL &&
+             c->inner_creds->vtable->create_security_connector != NULL);
+  /* If we are passed a call_creds, create a call composite to pass it
+     downstream. */
+  if (call_creds != NULL) {
+    grpc_call_credentials *composite_call_creds =
+        grpc_composite_call_credentials_create(c->call_creds, call_creds, NULL);
+    status = c->inner_creds->vtable->create_security_connector(
+        c->inner_creds, composite_call_creds, target, args, sc, new_args);
+    grpc_call_credentials_unref(composite_call_creds);
+  } else {
+    status = c->inner_creds->vtable->create_security_connector(
+        c->inner_creds, c->call_creds, target, args, sc, new_args);
+  }
+  return status;
+}
+
+static grpc_channel_credentials_vtable composite_channel_credentials_vtable = {
+    composite_channel_destruct, composite_channel_create_security_connector};
+
+grpc_channel_credentials *grpc_composite_channel_credentials_create(
+    grpc_channel_credentials *channel_creds, grpc_call_credentials *call_creds,
+    void *reserved) {
+  grpc_composite_channel_credentials *c = gpr_malloc(sizeof(*c));
+  memset(c, 0, sizeof(*c));
+  GPR_ASSERT(channel_creds != NULL && call_creds != NULL && reserved == NULL);
+  GRPC_API_TRACE(
+      "grpc_composite_channel_credentials_create(channel_creds=%p, "
+      "call_creds=%p, reserved=%p)",
+      3, (channel_creds, call_creds, reserved));
+  c->base.type = channel_creds->type;
+  c->base.vtable = &composite_channel_credentials_vtable;
+  gpr_ref_init(&c->base.refcount, 1);
+  c->inner_creds = grpc_channel_credentials_ref(channel_creds);
+  c->call_creds = grpc_call_credentials_ref(call_creds);
+  return &c->base;
+}
diff --git a/src/core/lib/security/credentials/composite/composite_credentials.h b/src/core/lib/security/credentials/composite/composite_credentials.h
new file mode 100644
index 0000000000..0d8966f464
--- /dev/null
+++ b/src/core/lib/security/credentials/composite/composite_credentials.h
@@ -0,0 +1,72 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_SECURITY_CREDENTIALS_COMPOSITE_COMPOSITE_CREDENTIALS_H
+#define GRPC_CORE_LIB_SECURITY_CREDENTIALS_COMPOSITE_COMPOSITE_CREDENTIALS_H
+
+#include "src/core/lib/security/credentials/credentials.h"
+
+typedef struct {
+  grpc_call_credentials **creds_array;
+  size_t num_creds;
+} grpc_call_credentials_array;
+
+const grpc_call_credentials_array *
+grpc_composite_call_credentials_get_credentials(
+    grpc_call_credentials *composite_creds);
+
+/* Returns creds if creds is of the specified type or the inner creds of the
+   specified type (if found), if the creds is of type COMPOSITE.
+   If composite_creds is not NULL, *composite_creds will point to creds if of
+   type COMPOSITE in case of success. */
+grpc_call_credentials *grpc_credentials_contains_type(
+    grpc_call_credentials *creds, const char *type,
+    grpc_call_credentials **composite_creds);
+
+/* -- Channel composite credentials. -- */
+
+typedef struct {
+  grpc_channel_credentials base;
+  grpc_channel_credentials *inner_creds;
+  grpc_call_credentials *call_creds;
+} grpc_composite_channel_credentials;
+
+/* -- Composite credentials. -- */
+
+typedef struct {
+  grpc_call_credentials base;
+  grpc_call_credentials_array inner;
+} grpc_composite_call_credentials;
+
+#endif /* GRPC_CORE_LIB_SECURITY_CREDENTIALS_COMPOSITE_COMPOSITE_CREDENTIALS_H \
+          */
diff --git a/src/core/lib/security/credentials/credentials.c b/src/core/lib/security/credentials/credentials.c
new file mode 100644
index 0000000000..7034ed57c6
--- /dev/null
+++ b/src/core/lib/security/credentials/credentials.c
@@ -0,0 +1,231 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/lib/security/credentials/credentials.h"
+
+#include <stdio.h>
+#include <string.h>
+
+#include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/channel/http_client_filter.h"
+#include "src/core/lib/http/httpcli.h"
+#include "src/core/lib/http/parser.h"
+#include "src/core/lib/iomgr/executor.h"
+#include "src/core/lib/json/json.h"
+#include "src/core/lib/support/string.h"
+#include "src/core/lib/surface/api_trace.h"
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/sync.h>
+#include <grpc/support/time.h>
+
+/* -- Common. -- */
+
+grpc_credentials_metadata_request *grpc_credentials_metadata_request_create(
+    grpc_call_credentials *creds, grpc_credentials_metadata_cb cb,
+    void *user_data) {
+  grpc_credentials_metadata_request *r =
+      gpr_malloc(sizeof(grpc_credentials_metadata_request));
+  r->creds = grpc_call_credentials_ref(creds);
+  r->cb = cb;
+  r->user_data = user_data;
+  return r;
+}
+
+void grpc_credentials_metadata_request_destroy(
+    grpc_credentials_metadata_request *r) {
+  grpc_call_credentials_unref(r->creds);
+  gpr_free(r);
+}
+
+grpc_channel_credentials *grpc_channel_credentials_ref(
+    grpc_channel_credentials *creds) {
+  if (creds == NULL) return NULL;
+  gpr_ref(&creds->refcount);
+  return creds;
+}
+
+void grpc_channel_credentials_unref(grpc_channel_credentials *creds) {
+  if (creds == NULL) return;
+  if (gpr_unref(&creds->refcount)) {
+    if (creds->vtable->destruct != NULL) creds->vtable->destruct(creds);
+    gpr_free(creds);
+  }
+}
+
+void grpc_channel_credentials_release(grpc_channel_credentials *creds) {
+  GRPC_API_TRACE("grpc_channel_credentials_release(creds=%p)", 1, (creds));
+  grpc_channel_credentials_unref(creds);
+}
+
+grpc_call_credentials *grpc_call_credentials_ref(grpc_call_credentials *creds) {
+  if (creds == NULL) return NULL;
+  gpr_ref(&creds->refcount);
+  return creds;
+}
+
+void grpc_call_credentials_unref(grpc_call_credentials *creds) {
+  if (creds == NULL) return;
+  if (gpr_unref(&creds->refcount)) {
+    if (creds->vtable->destruct != NULL) creds->vtable->destruct(creds);
+    gpr_free(creds);
+  }
+}
+
+void grpc_call_credentials_release(grpc_call_credentials *creds) {
+  GRPC_API_TRACE("grpc_call_credentials_release(creds=%p)", 1, (creds));
+  grpc_call_credentials_unref(creds);
+}
+
+void grpc_call_credentials_get_request_metadata(
+    grpc_exec_ctx *exec_ctx, grpc_call_credentials *creds,
+    grpc_pollset *pollset, grpc_auth_metadata_context context,
+    grpc_credentials_metadata_cb cb, void *user_data) {
+  if (creds == NULL || creds->vtable->get_request_metadata == NULL) {
+    if (cb != NULL) {
+      cb(exec_ctx, user_data, NULL, 0, GRPC_CREDENTIALS_OK, NULL);
+    }
+    return;
+  }
+  creds->vtable->get_request_metadata(exec_ctx, creds, pollset, context, cb,
+                                      user_data);
+}
+
+grpc_security_status grpc_channel_credentials_create_security_connector(
+    grpc_channel_credentials *channel_creds, const char *target,
+    const grpc_channel_args *args, grpc_channel_security_connector **sc,
+    grpc_channel_args **new_args) {
+  *new_args = NULL;
+  if (channel_creds == NULL) {
+    return GRPC_SECURITY_ERROR;
+  }
+  GPR_ASSERT(channel_creds->vtable->create_security_connector != NULL);
+  return channel_creds->vtable->create_security_connector(
+      channel_creds, NULL, target, args, sc, new_args);
+}
+
+grpc_server_credentials *grpc_server_credentials_ref(
+    grpc_server_credentials *creds) {
+  if (creds == NULL) return NULL;
+  gpr_ref(&creds->refcount);
+  return creds;
+}
+
+void grpc_server_credentials_unref(grpc_server_credentials *creds) {
+  if (creds == NULL) return;
+  if (gpr_unref(&creds->refcount)) {
+    if (creds->vtable->destruct != NULL) creds->vtable->destruct(creds);
+    if (creds->processor.destroy != NULL && creds->processor.state != NULL) {
+      creds->processor.destroy(creds->processor.state);
+    }
+    gpr_free(creds);
+  }
+}
+
+void grpc_server_credentials_release(grpc_server_credentials *creds) {
+  GRPC_API_TRACE("grpc_server_credentials_release(creds=%p)", 1, (creds));
+  grpc_server_credentials_unref(creds);
+}
+
+grpc_security_status grpc_server_credentials_create_security_connector(
+    grpc_server_credentials *creds, grpc_server_security_connector **sc) {
+  if (creds == NULL || creds->vtable->create_security_connector == NULL) {
+    gpr_log(GPR_ERROR, "Server credentials cannot create security context.");
+    return GRPC_SECURITY_ERROR;
+  }
+  return creds->vtable->create_security_connector(creds, sc);
+}
+
+void grpc_server_credentials_set_auth_metadata_processor(
+    grpc_server_credentials *creds, grpc_auth_metadata_processor processor) {
+  GRPC_API_TRACE(
+      "grpc_server_credentials_set_auth_metadata_processor("
+      "creds=%p, "
+      "processor=grpc_auth_metadata_processor { process: %p, state: %p })",
+      3, (creds, (void *)(intptr_t)processor.process, processor.state));
+  if (creds == NULL) return;
+  if (creds->processor.destroy != NULL && creds->processor.state != NULL) {
+    creds->processor.destroy(creds->processor.state);
+  }
+  creds->processor = processor;
+}
+
+static void server_credentials_pointer_arg_destroy(void *p) {
+  grpc_server_credentials_unref(p);
+}
+
+static void *server_credentials_pointer_arg_copy(void *p) {
+  return grpc_server_credentials_ref(p);
+}
+
+static int server_credentials_pointer_cmp(void *a, void *b) {
+  return GPR_ICMP(a, b);
+}
+
+static const grpc_arg_pointer_vtable cred_ptr_vtable = {
+    server_credentials_pointer_arg_copy, server_credentials_pointer_arg_destroy,
+    server_credentials_pointer_cmp};
+
+grpc_arg grpc_server_credentials_to_arg(grpc_server_credentials *p) {
+  grpc_arg arg;
+  memset(&arg, 0, sizeof(grpc_arg));
+  arg.type = GRPC_ARG_POINTER;
+  arg.key = GRPC_SERVER_CREDENTIALS_ARG;
+  arg.value.pointer.p = p;
+  arg.value.pointer.vtable = &cred_ptr_vtable;
+  return arg;
+}
+
+grpc_server_credentials *grpc_server_credentials_from_arg(const grpc_arg *arg) {
+  if (strcmp(arg->key, GRPC_SERVER_CREDENTIALS_ARG) != 0) return NULL;
+  if (arg->type != GRPC_ARG_POINTER) {
+    gpr_log(GPR_ERROR, "Invalid type %d for arg %s", arg->type,
+            GRPC_SERVER_CREDENTIALS_ARG);
+    return NULL;
+  }
+  return arg->value.pointer.p;
+}
+
+grpc_server_credentials *grpc_find_server_credentials_in_args(
+    const grpc_channel_args *args) {
+  size_t i;
+  if (args == NULL) return NULL;
+  for (i = 0; i < args->num_args; i++) {
+    grpc_server_credentials *p =
+        grpc_server_credentials_from_arg(&args->args[i]);
+    if (p != NULL) return p;
+  }
+  return NULL;
+}
diff --git a/src/core/lib/security/credentials.h b/src/core/lib/security/credentials/credentials.h
index 412b6e48fc..c6df6cdf2f 100644
--- a/src/core/lib/security/credentials.h
+++ b/src/core/lib/security/credentials/credentials.h
@@ -31,8 +31,8 @@
  *
  */
 
-#ifndef GRPC_CORE_LIB_SECURITY_CREDENTIALS_H
-#define GRPC_CORE_LIB_SECURITY_CREDENTIALS_H
+#ifndef GRPC_CORE_LIB_SECURITY_CREDENTIALS_CREDENTIALS_H
+#define GRPC_CORE_LIB_SECURITY_CREDENTIALS_CREDENTIALS_H
 
 #include <grpc/grpc.h>
 #include <grpc/grpc_security.h>
@@ -41,8 +41,7 @@
 
 #include "src/core/lib/http/httpcli.h"
 #include "src/core/lib/http/parser.h"
-#include "src/core/lib/security/json_token.h"
-#include "src/core/lib/security/security_connector.h"
+#include "src/core/lib/security/transport/security_connector.h"
 
 struct grpc_http_response;
 
@@ -69,10 +68,6 @@ typedef enum {
   "x-goog-iam-authorization-token"
 #define GRPC_IAM_AUTHORITY_SELECTOR_METADATA_KEY "x-goog-iam-authority-selector"
 
-#define GRPC_GOOGLE_CLOUD_SDK_CONFIG_DIRECTORY "gcloud"
-#define GRPC_GOOGLE_WELL_KNOWN_CREDENTIALS_FILE \
-  "application_default_credentials.json"
-
 #define GRPC_SECURE_TOKEN_REFRESH_THRESHOLD_SECS 60
 
 #define GRPC_COMPUTE_ENGINE_METADATA_HOST "metadata"
@@ -190,48 +185,11 @@ void grpc_call_credentials_get_request_metadata(
     grpc_pollset *pollset, grpc_auth_metadata_context context,
     grpc_credentials_metadata_cb cb, void *user_data);
 
-typedef struct {
-  grpc_call_credentials **creds_array;
-  size_t num_creds;
-} grpc_call_credentials_array;
-
-const grpc_call_credentials_array *
-grpc_composite_call_credentials_get_credentials(
-    grpc_call_credentials *composite_creds);
-
-/* Returns creds if creds is of the specified type or the inner creds of the
-   specified type (if found), if the creds is of type COMPOSITE.
-   If composite_creds is not NULL, *composite_creds will point to creds if of
-   type COMPOSITE in case of success. */
-grpc_call_credentials *grpc_credentials_contains_type(
-    grpc_call_credentials *creds, const char *type,
-    grpc_call_credentials **composite_creds);
-
-/* Exposed for testing only. */
-grpc_credentials_status
-grpc_oauth2_token_fetcher_credentials_parse_server_response(
-    const struct grpc_http_response *response,
-    grpc_credentials_md_store **token_md, gpr_timespec *token_lifetime);
-
-void grpc_flush_cached_google_default_credentials(void);
-
 /* Metadata-only credentials with the specified key and value where
    asynchronicity can be simulated for testing. */
 grpc_call_credentials *grpc_md_only_test_credentials_create(
     const char *md_key, const char *md_value, int is_async);
 
-/* Private constructor for jwt credentials from an already parsed json key.
-   Takes ownership of the key. */
-grpc_call_credentials *
-grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
-    grpc_auth_json_key key, gpr_timespec token_lifetime);
-
-/* Private constructor for refresh token credentials from an already parsed
-   refresh token. Takes ownership of the refresh token. */
-grpc_call_credentials *
-grpc_refresh_token_credentials_create_from_auth_refresh_token(
-    grpc_auth_refresh_token token);
-
 /* --- grpc_server_credentials. --- */
 
 typedef struct {
@@ -262,118 +220,19 @@ grpc_server_credentials *grpc_server_credentials_from_arg(const grpc_arg *arg);
 grpc_server_credentials *grpc_find_server_credentials_in_args(
     const grpc_channel_args *args);
 
-/* -- Fake transport security credentials. -- */
-
-/* Creates a fake transport security credentials object for testing. */
-grpc_channel_credentials *grpc_fake_transport_security_credentials_create(void);
-/* Creates a fake server transport security credentials object for testing. */
-grpc_server_credentials *grpc_fake_transport_security_server_credentials_create(
-    void);
-
-/* -- Ssl credentials. -- */
-
-typedef struct {
-  grpc_channel_credentials base;
-  grpc_ssl_config config;
-} grpc_ssl_credentials;
-
-typedef struct {
-  grpc_server_credentials base;
-  grpc_ssl_server_config config;
-} grpc_ssl_server_credentials;
-
-/* -- Channel composite credentials. -- */
-
-typedef struct {
-  grpc_channel_credentials base;
-  grpc_channel_credentials *inner_creds;
-  grpc_call_credentials *call_creds;
-} grpc_composite_channel_credentials;
-
-/* -- Jwt credentials -- */
+/* -- Credentials Metadata Request. -- */
 
 typedef struct {
-  grpc_call_credentials base;
-
-  /* Have a simple cache for now with just 1 entry. We could have a map based on
-     the service_url for a more sophisticated one. */
-  gpr_mu cache_mu;
-  struct {
-    grpc_credentials_md_store *jwt_md;
-    char *service_url;
-    gpr_timespec jwt_expiration;
-  } cached;
-
-  grpc_auth_json_key key;
-  gpr_timespec jwt_lifetime;
-} grpc_service_account_jwt_access_credentials;
-
-/* -- Oauth2TokenFetcher credentials --
-
-   This object is a base for credentials that need to acquire an oauth2 token
-   from an http service. */
-
-typedef struct grpc_credentials_metadata_request
-    grpc_credentials_metadata_request;
+  grpc_call_credentials *creds;
+  grpc_credentials_metadata_cb cb;
+  void *user_data;
+} grpc_credentials_metadata_request;
 
-typedef void (*grpc_fetch_oauth2_func)(grpc_exec_ctx *exec_ctx,
-                                       grpc_credentials_metadata_request *req,
-                                       grpc_httpcli_context *http_context,
-                                       grpc_pollset *pollset,
-                                       grpc_httpcli_response_cb response_cb,
-                                       gpr_timespec deadline);
+grpc_credentials_metadata_request *grpc_credentials_metadata_request_create(
+    grpc_call_credentials *creds, grpc_credentials_metadata_cb cb,
+    void *user_data);
 
-typedef struct {
-  grpc_call_credentials base;
-  gpr_mu mu;
-  grpc_credentials_md_store *access_token_md;
-  gpr_timespec token_expiration;
-  grpc_httpcli_context httpcli_context;
-  grpc_fetch_oauth2_func fetch_func;
-} grpc_oauth2_token_fetcher_credentials;
-
-/* -- GoogleRefreshToken credentials. -- */
-
-typedef struct {
-  grpc_oauth2_token_fetcher_credentials base;
-  grpc_auth_refresh_token refresh_token;
-} grpc_google_refresh_token_credentials;
-
-/* -- Oauth2 Access Token credentials. -- */
-
-typedef struct {
-  grpc_call_credentials base;
-  grpc_credentials_md_store *access_token_md;
-} grpc_access_token_credentials;
-
-/* --  Metadata-only Test credentials. -- */
-
-typedef struct {
-  grpc_call_credentials base;
-  grpc_credentials_md_store *md_store;
-  int is_async;
-} grpc_md_only_test_credentials;
-
-/* -- GoogleIAM credentials. -- */
-
-typedef struct {
-  grpc_call_credentials base;
-  grpc_credentials_md_store *iam_md;
-} grpc_google_iam_credentials;
-
-/* -- Composite credentials. -- */
-
-typedef struct {
-  grpc_call_credentials base;
-  grpc_call_credentials_array inner;
-} grpc_composite_call_credentials;
-
-/* -- Plugin credentials. -- */
-
-typedef struct {
-  grpc_call_credentials base;
-  grpc_metadata_credentials_plugin plugin;
-  grpc_credentials_md_store *plugin_md;
-} grpc_plugin_credentials;
+void grpc_credentials_metadata_request_destroy(
+    grpc_credentials_metadata_request *r);
 
-#endif /* GRPC_CORE_LIB_SECURITY_CREDENTIALS_H */
+#endif /* GRPC_CORE_LIB_SECURITY_CREDENTIALS_CREDENTIALS_H */
diff --git a/src/core/lib/security/credentials_metadata.c b/src/core/lib/security/credentials/credentials_metadata.c
index bd00194278..6a352aab3a 100644
--- a/src/core/lib/security/credentials_metadata.c
+++ b/src/core/lib/security/credentials/credentials_metadata.c
@@ -31,7 +31,7 @@
  *
  */
 
-#include "src/core/lib/security/credentials.h"
+#include "src/core/lib/security/credentials/credentials.h"
 
 #include <grpc/support/alloc.h>
 
diff --git a/src/core/lib/security/credentials/fake/fake_credentials.c b/src/core/lib/security/credentials/fake/fake_credentials.c
new file mode 100644
index 0000000000..8b518938cc
--- /dev/null
+++ b/src/core/lib/security/credentials/fake/fake_credentials.c
@@ -0,0 +1,138 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/lib/security/credentials/fake/fake_credentials.h"
+
+#include <string.h>
+
+#include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/iomgr/executor.h"
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+
+/* -- Fake transport security credentials. -- */
+
+static grpc_security_status fake_transport_security_create_security_connector(
+    grpc_channel_credentials *c, grpc_call_credentials *call_creds,
+    const char *target, const grpc_channel_args *args,
+    grpc_channel_security_connector **sc, grpc_channel_args **new_args) {
+  *sc = grpc_fake_channel_security_connector_create(call_creds);
+  return GRPC_SECURITY_OK;
+}
+
+static grpc_security_status
+fake_transport_security_server_create_security_connector(
+    grpc_server_credentials *c, grpc_server_security_connector **sc) {
+  *sc = grpc_fake_server_security_connector_create();
+  return GRPC_SECURITY_OK;
+}
+
+static grpc_channel_credentials_vtable
+    fake_transport_security_credentials_vtable = {
+        NULL, fake_transport_security_create_security_connector};
+
+static grpc_server_credentials_vtable
+    fake_transport_security_server_credentials_vtable = {
+        NULL, fake_transport_security_server_create_security_connector};
+
+grpc_channel_credentials *grpc_fake_transport_security_credentials_create(
+    void) {
+  grpc_channel_credentials *c = gpr_malloc(sizeof(grpc_channel_credentials));
+  memset(c, 0, sizeof(grpc_channel_credentials));
+  c->type = GRPC_CHANNEL_CREDENTIALS_TYPE_FAKE_TRANSPORT_SECURITY;
+  c->vtable = &fake_transport_security_credentials_vtable;
+  gpr_ref_init(&c->refcount, 1);
+  return c;
+}
+
+grpc_server_credentials *grpc_fake_transport_security_server_credentials_create(
+    void) {
+  grpc_server_credentials *c = gpr_malloc(sizeof(grpc_server_credentials));
+  memset(c, 0, sizeof(grpc_server_credentials));
+  c->type = GRPC_CHANNEL_CREDENTIALS_TYPE_FAKE_TRANSPORT_SECURITY;
+  gpr_ref_init(&c->refcount, 1);
+  c->vtable = &fake_transport_security_server_credentials_vtable;
+  return c;
+}
+
+/* -- Metadata-only test credentials. -- */
+
+static void md_only_test_destruct(grpc_call_credentials *creds) {
+  grpc_md_only_test_credentials *c = (grpc_md_only_test_credentials *)creds;
+  grpc_credentials_md_store_unref(c->md_store);
+}
+
+static void on_simulated_token_fetch_done(grpc_exec_ctx *exec_ctx,
+                                          void *user_data, bool success) {
+  grpc_credentials_metadata_request *r =
+      (grpc_credentials_metadata_request *)user_data;
+  grpc_md_only_test_credentials *c = (grpc_md_only_test_credentials *)r->creds;
+  r->cb(exec_ctx, r->user_data, c->md_store->entries, c->md_store->num_entries,
+        GRPC_CREDENTIALS_OK, NULL);
+  grpc_credentials_metadata_request_destroy(r);
+}
+
+static void md_only_test_get_request_metadata(
+    grpc_exec_ctx *exec_ctx, grpc_call_credentials *creds,
+    grpc_pollset *pollset, grpc_auth_metadata_context context,
+    grpc_credentials_metadata_cb cb, void *user_data) {
+  grpc_md_only_test_credentials *c = (grpc_md_only_test_credentials *)creds;
+
+  if (c->is_async) {
+    grpc_credentials_metadata_request *cb_arg =
+        grpc_credentials_metadata_request_create(creds, cb, user_data);
+    grpc_executor_enqueue(
+        grpc_closure_create(on_simulated_token_fetch_done, cb_arg), true);
+  } else {
+    cb(exec_ctx, user_data, c->md_store->entries, 1, GRPC_CREDENTIALS_OK, NULL);
+  }
+}
+
+static grpc_call_credentials_vtable md_only_test_vtable = {
+    md_only_test_destruct, md_only_test_get_request_metadata};
+
+grpc_call_credentials *grpc_md_only_test_credentials_create(
+    const char *md_key, const char *md_value, int is_async) {
+  grpc_md_only_test_credentials *c =
+      gpr_malloc(sizeof(grpc_md_only_test_credentials));
+  memset(c, 0, sizeof(grpc_md_only_test_credentials));
+  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_OAUTH2;
+  c->base.vtable = &md_only_test_vtable;
+  gpr_ref_init(&c->base.refcount, 1);
+  c->md_store = grpc_credentials_md_store_create(1);
+  grpc_credentials_md_store_add_cstrings(c->md_store, md_key, md_value);
+  c->is_async = is_async;
+  return &c->base;
+}
diff --git a/src/core/lib/security/credentials/fake/fake_credentials.h b/src/core/lib/security/credentials/fake/fake_credentials.h
new file mode 100644
index 0000000000..9cf38084a3
--- /dev/null
+++ b/src/core/lib/security/credentials/fake/fake_credentials.h
@@ -0,0 +1,56 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_SECURITY_CREDENTIALS_FAKE_FAKE_CREDENTIALS_H
+#define GRPC_CORE_LIB_SECURITY_CREDENTIALS_FAKE_FAKE_CREDENTIALS_H
+
+#include "src/core/lib/security/credentials/credentials.h"
+
+/* -- Fake transport security credentials. -- */
+
+/* Creates a fake transport security credentials object for testing. */
+grpc_channel_credentials *grpc_fake_transport_security_credentials_create(void);
+
+/* Creates a fake server transport security credentials object for testing. */
+grpc_server_credentials *grpc_fake_transport_security_server_credentials_create(
+    void);
+
+/* --  Metadata-only Test credentials. -- */
+
+typedef struct {
+  grpc_call_credentials base;
+  grpc_credentials_md_store *md_store;
+  int is_async;
+} grpc_md_only_test_credentials;
+
+#endif /* GRPC_CORE_LIB_SECURITY_CREDENTIALS_FAKE_FAKE_CREDENTIALS_H */
diff --git a/src/core/lib/security/credentials_posix.c b/src/core/lib/security/credentials/google_default/credentials_posix.c
index a07de182a0..42c9d7f997 100644
--- a/src/core/lib/security/credentials_posix.c
+++ b/src/core/lib/security/credentials/google_default/credentials_posix.c
@@ -35,7 +35,7 @@
 
 #ifdef GPR_POSIX_FILE
 
-#include "src/core/lib/security/credentials.h"
+#include "src/core/lib/security/credentials/google_default/google_default_credentials.h"
 
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
diff --git a/src/core/lib/security/credentials_win32.c b/src/core/lib/security/credentials/google_default/credentials_windows.c
index d29847af38..208b8fd9ad 100644
--- a/src/core/lib/security/credentials_win32.c
+++ b/src/core/lib/security/credentials/google_default/credentials_windows.c
@@ -33,9 +33,9 @@
 
 #include <grpc/support/port_platform.h>
 
-#ifdef GPR_WIN32
+#ifdef GPR_WINDOWS
 
-#include "src/core/lib/security/credentials.h"
+#include "src/core/lib/security/credentials/google_default/google_default_credentials.h"
 
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
@@ -58,4 +58,4 @@ char *grpc_get_well_known_google_credentials_file_path_impl(void) {
   return result;
 }
 
-#endif /* GPR_WIN32 */
+#endif /* GPR_WINDOWS */
diff --git a/src/core/lib/security/google_default_credentials.c b/src/core/lib/security/credentials/google_default/google_default_credentials.c
index 236f1d7fa7..a521d95abc 100644
--- a/src/core/lib/security/google_default_credentials.c
+++ b/src/core/lib/security/credentials/google_default/google_default_credentials.c
@@ -31,7 +31,7 @@
  *
  */
 
-#include "src/core/lib/security/credentials.h"
+#include "src/core/lib/security/credentials/credentials.h"
 
 #include <string.h>
 
@@ -41,6 +41,8 @@
 
 #include "src/core/lib/http/httpcli.h"
 #include "src/core/lib/http/parser.h"
+#include "src/core/lib/security/credentials/jwt/jwt_credentials.h"
+#include "src/core/lib/security/credentials/oauth2/oauth2_credentials.h"
 #include "src/core/lib/support/env.h"
 #include "src/core/lib/support/load_file.h"
 #include "src/core/lib/surface/api_trace.h"
diff --git a/src/core/lib/security/credentials/google_default/google_default_credentials.h b/src/core/lib/security/credentials/google_default/google_default_credentials.h
new file mode 100644
index 0000000000..fac4377e2c
--- /dev/null
+++ b/src/core/lib/security/credentials/google_default/google_default_credentials.h
@@ -0,0 +1,46 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_SECURITY_CREDENTIALS_GOOGLE_DEFAULT_GOOGLE_DEFAULT_CREDENTIALS_H
+#define GRPC_CORE_LIB_SECURITY_CREDENTIALS_GOOGLE_DEFAULT_GOOGLE_DEFAULT_CREDENTIALS_H
+
+#include "src/core/lib/security/credentials/credentials.h"
+
+#define GRPC_GOOGLE_CLOUD_SDK_CONFIG_DIRECTORY "gcloud"
+#define GRPC_GOOGLE_WELL_KNOWN_CREDENTIALS_FILE \
+  "application_default_credentials.json"
+
+void grpc_flush_cached_google_default_credentials(void);
+
+#endif /* GRPC_CORE_LIB_SECURITY_CREDENTIALS_GOOGLE_DEFAULT_GOOGLE_DEFAULT_CREDENTIALS_H \
+          */
diff --git a/src/core/lib/security/credentials/iam/iam_credentials.c b/src/core/lib/security/credentials/iam/iam_credentials.c
new file mode 100644
index 0000000000..66e7b0e3db
--- /dev/null
+++ b/src/core/lib/security/credentials/iam/iam_credentials.c
@@ -0,0 +1,85 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/lib/security/credentials/iam/iam_credentials.h"
+
+#include <string.h>
+
+#include "src/core/lib/surface/api_trace.h"
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/sync.h>
+
+static void iam_destruct(grpc_call_credentials *creds) {
+  grpc_google_iam_credentials *c = (grpc_google_iam_credentials *)creds;
+  grpc_credentials_md_store_unref(c->iam_md);
+}
+
+static void iam_get_request_metadata(grpc_exec_ctx *exec_ctx,
+                                     grpc_call_credentials *creds,
+                                     grpc_pollset *pollset,
+                                     grpc_auth_metadata_context context,
+                                     grpc_credentials_metadata_cb cb,
+                                     void *user_data) {
+  grpc_google_iam_credentials *c = (grpc_google_iam_credentials *)creds;
+  cb(exec_ctx, user_data, c->iam_md->entries, c->iam_md->num_entries,
+     GRPC_CREDENTIALS_OK, NULL);
+}
+
+static grpc_call_credentials_vtable iam_vtable = {iam_destruct,
+                                                  iam_get_request_metadata};
+
+grpc_call_credentials *grpc_google_iam_credentials_create(
+    const char *token, const char *authority_selector, void *reserved) {
+  grpc_google_iam_credentials *c;
+  GRPC_API_TRACE(
+      "grpc_iam_credentials_create(token=%s, authority_selector=%s, "
+      "reserved=%p)",
+      3, (token, authority_selector, reserved));
+  GPR_ASSERT(reserved == NULL);
+  GPR_ASSERT(token != NULL);
+  GPR_ASSERT(authority_selector != NULL);
+  c = gpr_malloc(sizeof(grpc_google_iam_credentials));
+  memset(c, 0, sizeof(grpc_google_iam_credentials));
+  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_IAM;
+  c->base.vtable = &iam_vtable;
+  gpr_ref_init(&c->base.refcount, 1);
+  c->iam_md = grpc_credentials_md_store_create(2);
+  grpc_credentials_md_store_add_cstrings(
+      c->iam_md, GRPC_IAM_AUTHORIZATION_TOKEN_METADATA_KEY, token);
+  grpc_credentials_md_store_add_cstrings(
+      c->iam_md, GRPC_IAM_AUTHORITY_SELECTOR_METADATA_KEY, authority_selector);
+  return &c->base;
+}
diff --git a/src/core/lib/security/credentials/iam/iam_credentials.h b/src/core/lib/security/credentials/iam/iam_credentials.h
new file mode 100644
index 0000000000..af54faa586
--- /dev/null
+++ b/src/core/lib/security/credentials/iam/iam_credentials.h
@@ -0,0 +1,44 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_SECURITY_CREDENTIALS_IAM_IAM_CREDENTIALS_H
+#define GRPC_CORE_LIB_SECURITY_CREDENTIALS_IAM_IAM_CREDENTIALS_H
+
+#include "src/core/lib/security/credentials/credentials.h"
+
+typedef struct {
+  grpc_call_credentials base;
+  grpc_credentials_md_store *iam_md;
+} grpc_google_iam_credentials;
+
+#endif /* GRPC_CORE_LIB_SECURITY_CREDENTIALS_IAM_IAM_CREDENTIALS_H */
diff --git a/src/core/lib/security/json_token.c b/src/core/lib/security/credentials/jwt/json_token.c
index d5bc2c8d60..354c13133e 100644
--- a/src/core/lib/security/json_token.c
+++ b/src/core/lib/security/credentials/jwt/json_token.c
@@ -31,7 +31,7 @@
  *
  */
 
-#include "src/core/lib/security/json_token.h"
+#include "src/core/lib/security/credentials/jwt/json_token.h"
 
 #include <string.h>
 
@@ -39,7 +39,8 @@
 #include <grpc/support/log.h>
 #include <grpc/support/string_util.h>
 
-#include "src/core/lib/security/b64.h"
+#include "src/core/lib/security/util/b64.h"
+#include "src/core/lib/security/util/json_util.h"
 #include "src/core/lib/support/string.h"
 
 #include <openssl/bio.h>
@@ -66,28 +67,6 @@ static grpc_jwt_encode_and_sign_override g_jwt_encode_and_sign_override = NULL;
 
 /* --- grpc_auth_json_key. --- */
 
-static const char *json_get_string_property(const grpc_json *json,
-                                            const char *prop_name) {
-  grpc_json *child;
-  for (child = json->child; child != NULL; child = child->next) {
-    if (strcmp(child->key, prop_name) == 0) break;
-  }
-  if (child == NULL || child->type != GRPC_JSON_STRING) {
-    gpr_log(GPR_ERROR, "Invalid or missing %s property.", prop_name);
-    return NULL;
-  }
-  return child->value;
-}
-
-static int set_json_key_string_property(const grpc_json *json,
-                                        const char *prop_name,
-                                        char **json_key_field) {
-  const char *prop_value = json_get_string_property(json, prop_name);
-  if (prop_value == NULL) return 0;
-  *json_key_field = gpr_strdup(prop_value);
-  return 1;
-}
-
 int grpc_auth_json_key_is_valid(const grpc_auth_json_key *json_key) {
   return (json_key != NULL) &&
          strcmp(json_key->type, GRPC_AUTH_JSON_TYPE_INVALID);
@@ -106,22 +85,22 @@ grpc_auth_json_key grpc_auth_json_key_create_from_json(const grpc_json *json) {
     goto end;
   }
 
-  prop_value = json_get_string_property(json, "type");
+  prop_value = grpc_json_get_string_property(json, "type");
   if (prop_value == NULL ||
       strcmp(prop_value, GRPC_AUTH_JSON_TYPE_SERVICE_ACCOUNT)) {
     goto end;
   }
   result.type = GRPC_AUTH_JSON_TYPE_SERVICE_ACCOUNT;
 
-  if (!set_json_key_string_property(json, "private_key_id",
-                                    &result.private_key_id) ||
-      !set_json_key_string_property(json, "client_id", &result.client_id) ||
-      !set_json_key_string_property(json, "client_email",
-                                    &result.client_email)) {
+  if (!grpc_copy_json_string_property(json, "private_key_id",
+                                      &result.private_key_id) ||
+      !grpc_copy_json_string_property(json, "client_id", &result.client_id) ||
+      !grpc_copy_json_string_property(json, "client_email",
+                                      &result.client_email)) {
     goto end;
   }
 
-  prop_value = json_get_string_property(json, "private_key");
+  prop_value = grpc_json_get_string_property(json, "private_key");
   if (prop_value == NULL) {
     goto end;
   }
@@ -339,73 +318,3 @@ void grpc_jwt_encode_and_sign_set_override(
     grpc_jwt_encode_and_sign_override func) {
   g_jwt_encode_and_sign_override = func;
 }
-
-/* --- grpc_auth_refresh_token --- */
-
-int grpc_auth_refresh_token_is_valid(
-    const grpc_auth_refresh_token *refresh_token) {
-  return (refresh_token != NULL) &&
-         strcmp(refresh_token->type, GRPC_AUTH_JSON_TYPE_INVALID);
-}
-
-grpc_auth_refresh_token grpc_auth_refresh_token_create_from_json(
-    const grpc_json *json) {
-  grpc_auth_refresh_token result;
-  const char *prop_value;
-  int success = 0;
-
-  memset(&result, 0, sizeof(grpc_auth_refresh_token));
-  result.type = GRPC_AUTH_JSON_TYPE_INVALID;
-  if (json == NULL) {
-    gpr_log(GPR_ERROR, "Invalid json.");
-    goto end;
-  }
-
-  prop_value = json_get_string_property(json, "type");
-  if (prop_value == NULL ||
-      strcmp(prop_value, GRPC_AUTH_JSON_TYPE_AUTHORIZED_USER)) {
-    goto end;
-  }
-  result.type = GRPC_AUTH_JSON_TYPE_AUTHORIZED_USER;
-
-  if (!set_json_key_string_property(json, "client_secret",
-                                    &result.client_secret) ||
-      !set_json_key_string_property(json, "client_id", &result.client_id) ||
-      !set_json_key_string_property(json, "refresh_token",
-                                    &result.refresh_token)) {
-    goto end;
-  }
-  success = 1;
-
-end:
-  if (!success) grpc_auth_refresh_token_destruct(&result);
-  return result;
-}
-
-grpc_auth_refresh_token grpc_auth_refresh_token_create_from_string(
-    const char *json_string) {
-  char *scratchpad = gpr_strdup(json_string);
-  grpc_json *json = grpc_json_parse_string(scratchpad);
-  grpc_auth_refresh_token result =
-      grpc_auth_refresh_token_create_from_json(json);
-  if (json != NULL) grpc_json_destroy(json);
-  gpr_free(scratchpad);
-  return result;
-}
-
-void grpc_auth_refresh_token_destruct(grpc_auth_refresh_token *refresh_token) {
-  if (refresh_token == NULL) return;
-  refresh_token->type = GRPC_AUTH_JSON_TYPE_INVALID;
-  if (refresh_token->client_id != NULL) {
-    gpr_free(refresh_token->client_id);
-    refresh_token->client_id = NULL;
-  }
-  if (refresh_token->client_secret != NULL) {
-    gpr_free(refresh_token->client_secret);
-    refresh_token->client_secret = NULL;
-  }
-  if (refresh_token->refresh_token != NULL) {
-    gpr_free(refresh_token->refresh_token);
-    refresh_token->refresh_token = NULL;
-  }
-}
diff --git a/src/core/lib/security/json_token.h b/src/core/lib/security/credentials/jwt/json_token.h
index 123fa652fd..07fc5bf0e0 100644
--- a/src/core/lib/security/json_token.h
+++ b/src/core/lib/security/credentials/jwt/json_token.h
@@ -31,8 +31,8 @@
  *
  */
 
-#ifndef GRPC_CORE_LIB_SECURITY_JSON_TOKEN_H
-#define GRPC_CORE_LIB_SECURITY_JSON_TOKEN_H
+#ifndef GRPC_CORE_LIB_SECURITY_CREDENTIALS_JWT_JSON_TOKEN_H
+#define GRPC_CORE_LIB_SECURITY_CREDENTIALS_JWT_JSON_TOKEN_H
 
 #include <grpc/support/slice.h>
 #include <openssl/rsa.h>
@@ -43,10 +43,6 @@
 
 #define GRPC_JWT_OAUTH2_AUDIENCE "https://www.googleapis.com/oauth2/v3/token"
 
-#define GRPC_AUTH_JSON_TYPE_INVALID "invalid"
-#define GRPC_AUTH_JSON_TYPE_SERVICE_ACCOUNT "service_account"
-#define GRPC_AUTH_JSON_TYPE_AUTHORIZED_USER "authorized_user"
-
 /* --- auth_json_key parsing. --- */
 
 typedef struct {
@@ -89,30 +85,4 @@ typedef char *(*grpc_jwt_encode_and_sign_override)(
 void grpc_jwt_encode_and_sign_set_override(
     grpc_jwt_encode_and_sign_override func);
 
-/* --- auth_refresh_token parsing. --- */
-
-typedef struct {
-  const char *type;
-  char *client_id;
-  char *client_secret;
-  char *refresh_token;
-} grpc_auth_refresh_token;
-
-/* Returns 1 if the object is valid, 0 otherwise. */
-int grpc_auth_refresh_token_is_valid(
-    const grpc_auth_refresh_token *refresh_token);
-
-/* Creates a refresh token object from string. Returns an invalid object if a
-   parsing error has been encountered. */
-grpc_auth_refresh_token grpc_auth_refresh_token_create_from_string(
-    const char *json_string);
-
-/* Creates a refresh token object from parsed json. Returns an invalid object if
-   a parsing error has been encountered. */
-grpc_auth_refresh_token grpc_auth_refresh_token_create_from_json(
-    const grpc_json *json);
-
-/* Destructs the object. */
-void grpc_auth_refresh_token_destruct(grpc_auth_refresh_token *refresh_token);
-
-#endif /* GRPC_CORE_LIB_SECURITY_JSON_TOKEN_H */
+#endif /* GRPC_CORE_LIB_SECURITY_CREDENTIALS_JWT_JSON_TOKEN_H */
diff --git a/src/core/lib/security/credentials/jwt/jwt_credentials.c b/src/core/lib/security/credentials/jwt/jwt_credentials.c
new file mode 100644
index 0000000000..0d29729da1
--- /dev/null
+++ b/src/core/lib/security/credentials/jwt/jwt_credentials.c
@@ -0,0 +1,160 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/lib/security/credentials/jwt/jwt_credentials.h"
+
+#include <string.h>
+
+#include "src/core/lib/surface/api_trace.h"
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/sync.h>
+
+static void jwt_reset_cache(grpc_service_account_jwt_access_credentials *c) {
+  if (c->cached.jwt_md != NULL) {
+    grpc_credentials_md_store_unref(c->cached.jwt_md);
+    c->cached.jwt_md = NULL;
+  }
+  if (c->cached.service_url != NULL) {
+    gpr_free(c->cached.service_url);
+    c->cached.service_url = NULL;
+  }
+  c->cached.jwt_expiration = gpr_inf_past(GPR_CLOCK_REALTIME);
+}
+
+static void jwt_destruct(grpc_call_credentials *creds) {
+  grpc_service_account_jwt_access_credentials *c =
+      (grpc_service_account_jwt_access_credentials *)creds;
+  grpc_auth_json_key_destruct(&c->key);
+  jwt_reset_cache(c);
+  gpr_mu_destroy(&c->cache_mu);
+}
+
+static void jwt_get_request_metadata(grpc_exec_ctx *exec_ctx,
+                                     grpc_call_credentials *creds,
+                                     grpc_pollset *pollset,
+                                     grpc_auth_metadata_context context,
+                                     grpc_credentials_metadata_cb cb,
+                                     void *user_data) {
+  grpc_service_account_jwt_access_credentials *c =
+      (grpc_service_account_jwt_access_credentials *)creds;
+  gpr_timespec refresh_threshold = gpr_time_from_seconds(
+      GRPC_SECURE_TOKEN_REFRESH_THRESHOLD_SECS, GPR_TIMESPAN);
+
+  /* See if we can return a cached jwt. */
+  grpc_credentials_md_store *jwt_md = NULL;
+  {
+    gpr_mu_lock(&c->cache_mu);
+    if (c->cached.service_url != NULL &&
+        strcmp(c->cached.service_url, context.service_url) == 0 &&
+        c->cached.jwt_md != NULL &&
+        (gpr_time_cmp(gpr_time_sub(c->cached.jwt_expiration,
+                                   gpr_now(GPR_CLOCK_REALTIME)),
+                      refresh_threshold) > 0)) {
+      jwt_md = grpc_credentials_md_store_ref(c->cached.jwt_md);
+    }
+    gpr_mu_unlock(&c->cache_mu);
+  }
+
+  if (jwt_md == NULL) {
+    char *jwt = NULL;
+    /* Generate a new jwt. */
+    gpr_mu_lock(&c->cache_mu);
+    jwt_reset_cache(c);
+    jwt = grpc_jwt_encode_and_sign(&c->key, context.service_url,
+                                   c->jwt_lifetime, NULL);
+    if (jwt != NULL) {
+      char *md_value;
+      gpr_asprintf(&md_value, "Bearer %s", jwt);
+      gpr_free(jwt);
+      c->cached.jwt_expiration =
+          gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), c->jwt_lifetime);
+      c->cached.service_url = gpr_strdup(context.service_url);
+      c->cached.jwt_md = grpc_credentials_md_store_create(1);
+      grpc_credentials_md_store_add_cstrings(
+          c->cached.jwt_md, GRPC_AUTHORIZATION_METADATA_KEY, md_value);
+      gpr_free(md_value);
+      jwt_md = grpc_credentials_md_store_ref(c->cached.jwt_md);
+    }
+    gpr_mu_unlock(&c->cache_mu);
+  }
+
+  if (jwt_md != NULL) {
+    cb(exec_ctx, user_data, jwt_md->entries, jwt_md->num_entries,
+       GRPC_CREDENTIALS_OK, NULL);
+    grpc_credentials_md_store_unref(jwt_md);
+  } else {
+    cb(exec_ctx, user_data, NULL, 0, GRPC_CREDENTIALS_ERROR, NULL);
+  }
+}
+
+static grpc_call_credentials_vtable jwt_vtable = {jwt_destruct,
+                                                  jwt_get_request_metadata};
+
+grpc_call_credentials *
+grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
+    grpc_auth_json_key key, gpr_timespec token_lifetime) {
+  grpc_service_account_jwt_access_credentials *c;
+  if (!grpc_auth_json_key_is_valid(&key)) {
+    gpr_log(GPR_ERROR, "Invalid input for jwt credentials creation");
+    return NULL;
+  }
+  c = gpr_malloc(sizeof(grpc_service_account_jwt_access_credentials));
+  memset(c, 0, sizeof(grpc_service_account_jwt_access_credentials));
+  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_JWT;
+  gpr_ref_init(&c->base.refcount, 1);
+  c->base.vtable = &jwt_vtable;
+  c->key = key;
+  c->jwt_lifetime = token_lifetime;
+  gpr_mu_init(&c->cache_mu);
+  jwt_reset_cache(c);
+  return &c->base;
+}
+
+grpc_call_credentials *grpc_service_account_jwt_access_credentials_create(
+    const char *json_key, gpr_timespec token_lifetime, void *reserved) {
+  GRPC_API_TRACE(
+      "grpc_service_account_jwt_access_credentials_create("
+      "json_key=%s, "
+      "token_lifetime="
+      "gpr_timespec { tv_sec: %lld, tv_nsec: %d, clock_type: %d }, "
+      "reserved=%p)",
+      5,
+      (json_key, (long long)token_lifetime.tv_sec, (int)token_lifetime.tv_nsec,
+       (int)token_lifetime.clock_type, reserved));
+  GPR_ASSERT(reserved == NULL);
+  return grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
+      grpc_auth_json_key_create_from_string(json_key), token_lifetime);
+}
diff --git a/src/core/lib/security/credentials/jwt/jwt_credentials.h b/src/core/lib/security/credentials/jwt/jwt_credentials.h
new file mode 100644
index 0000000000..d572606179
--- /dev/null
+++ b/src/core/lib/security/credentials/jwt/jwt_credentials.h
@@ -0,0 +1,62 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_SECURITY_CREDENTIALS_JWT_JWT_CREDENTIALS_H
+#define GRPC_CORE_LIB_SECURITY_CREDENTIALS_JWT_JWT_CREDENTIALS_H
+
+#include "src/core/lib/security/credentials/credentials.h"
+#include "src/core/lib/security/credentials/jwt/json_token.h"
+
+typedef struct {
+  grpc_call_credentials base;
+
+  // Have a simple cache for now with just 1 entry. We could have a map based on
+  // the service_url for a more sophisticated one.
+  gpr_mu cache_mu;
+  struct {
+    grpc_credentials_md_store *jwt_md;
+    char *service_url;
+    gpr_timespec jwt_expiration;
+  } cached;
+
+  grpc_auth_json_key key;
+  gpr_timespec jwt_lifetime;
+} grpc_service_account_jwt_access_credentials;
+
+// Private constructor for jwt credentials from an already parsed json key.
+// Takes ownership of the key.
+grpc_call_credentials *
+grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
+    grpc_auth_json_key key, gpr_timespec token_lifetime);
+
+#endif /* GRPC_CORE_LIB_SECURITY_CREDENTIALS_JWT_JWT_CREDENTIALS_H */
diff --git a/src/core/lib/security/jwt_verifier.c b/src/core/lib/security/credentials/jwt/jwt_verifier.c
index 0e012294de..cd6c7ce392 100644
--- a/src/core/lib/security/jwt_verifier.c
+++ b/src/core/lib/security/credentials/jwt/jwt_verifier.c
@@ -31,13 +31,13 @@
  *
  */
 
-#include "src/core/lib/security/jwt_verifier.h"
+#include "src/core/lib/security/credentials/jwt/jwt_verifier.h"
 
 #include <limits.h>
 #include <string.h>
 
 #include "src/core/lib/http/httpcli.h"
-#include "src/core/lib/security/b64.h"
+#include "src/core/lib/security/util/b64.h"
 #include "src/core/lib/tsi/ssl_types.h"
 
 #include <grpc/support/alloc.h>
diff --git a/src/core/lib/security/jwt_verifier.h b/src/core/lib/security/credentials/jwt/jwt_verifier.h
index 98a4f6b116..b0f6d1c240 100644
--- a/src/core/lib/security/jwt_verifier.h
+++ b/src/core/lib/security/credentials/jwt/jwt_verifier.h
@@ -31,8 +31,8 @@
  *
  */
 
-#ifndef GRPC_CORE_LIB_SECURITY_JWT_VERIFIER_H
-#define GRPC_CORE_LIB_SECURITY_JWT_VERIFIER_H
+#ifndef GRPC_CORE_LIB_SECURITY_CREDENTIALS_JWT_JWT_VERIFIER_H
+#define GRPC_CORE_LIB_SECURITY_CREDENTIALS_JWT_JWT_VERIFIER_H
 
 #include "src/core/lib/iomgr/pollset.h"
 #include "src/core/lib/json/json.h"
@@ -133,4 +133,4 @@ grpc_jwt_claims *grpc_jwt_claims_from_json(grpc_json *json, gpr_slice buffer);
 grpc_jwt_verifier_status grpc_jwt_claims_check(const grpc_jwt_claims *claims,
                                                const char *audience);
 
-#endif /* GRPC_CORE_LIB_SECURITY_JWT_VERIFIER_H */
+#endif /* GRPC_CORE_LIB_SECURITY_CREDENTIALS_JWT_JWT_VERIFIER_H */
diff --git a/src/core/lib/security/credentials/oauth2/oauth2_credentials.c b/src/core/lib/security/credentials/oauth2/oauth2_credentials.c
new file mode 100644
index 0000000000..81457183d2
--- /dev/null
+++ b/src/core/lib/security/credentials/oauth2/oauth2_credentials.c
@@ -0,0 +1,429 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/lib/security/credentials/oauth2/oauth2_credentials.h"
+
+#include <string.h>
+
+#include "src/core/lib/security/util/json_util.h"
+#include "src/core/lib/surface/api_trace.h"
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+
+//
+// Auth Refresh Token.
+//
+
+int grpc_auth_refresh_token_is_valid(
+    const grpc_auth_refresh_token *refresh_token) {
+  return (refresh_token != NULL) &&
+         strcmp(refresh_token->type, GRPC_AUTH_JSON_TYPE_INVALID);
+}
+
+grpc_auth_refresh_token grpc_auth_refresh_token_create_from_json(
+    const grpc_json *json) {
+  grpc_auth_refresh_token result;
+  const char *prop_value;
+  int success = 0;
+
+  memset(&result, 0, sizeof(grpc_auth_refresh_token));
+  result.type = GRPC_AUTH_JSON_TYPE_INVALID;
+  if (json == NULL) {
+    gpr_log(GPR_ERROR, "Invalid json.");
+    goto end;
+  }
+
+  prop_value = grpc_json_get_string_property(json, "type");
+  if (prop_value == NULL ||
+      strcmp(prop_value, GRPC_AUTH_JSON_TYPE_AUTHORIZED_USER)) {
+    goto end;
+  }
+  result.type = GRPC_AUTH_JSON_TYPE_AUTHORIZED_USER;
+
+  if (!grpc_copy_json_string_property(json, "client_secret",
+                                      &result.client_secret) ||
+      !grpc_copy_json_string_property(json, "client_id", &result.client_id) ||
+      !grpc_copy_json_string_property(json, "refresh_token",
+                                      &result.refresh_token)) {
+    goto end;
+  }
+  success = 1;
+
+end:
+  if (!success) grpc_auth_refresh_token_destruct(&result);
+  return result;
+}
+
+grpc_auth_refresh_token grpc_auth_refresh_token_create_from_string(
+    const char *json_string) {
+  char *scratchpad = gpr_strdup(json_string);
+  grpc_json *json = grpc_json_parse_string(scratchpad);
+  grpc_auth_refresh_token result =
+      grpc_auth_refresh_token_create_from_json(json);
+  if (json != NULL) grpc_json_destroy(json);
+  gpr_free(scratchpad);
+  return result;
+}
+
+void grpc_auth_refresh_token_destruct(grpc_auth_refresh_token *refresh_token) {
+  if (refresh_token == NULL) return;
+  refresh_token->type = GRPC_AUTH_JSON_TYPE_INVALID;
+  if (refresh_token->client_id != NULL) {
+    gpr_free(refresh_token->client_id);
+    refresh_token->client_id = NULL;
+  }
+  if (refresh_token->client_secret != NULL) {
+    gpr_free(refresh_token->client_secret);
+    refresh_token->client_secret = NULL;
+  }
+  if (refresh_token->refresh_token != NULL) {
+    gpr_free(refresh_token->refresh_token);
+    refresh_token->refresh_token = NULL;
+  }
+}
+
+//
+// Oauth2 Token Fetcher credentials.
+//
+
+static void oauth2_token_fetcher_destruct(grpc_call_credentials *creds) {
+  grpc_oauth2_token_fetcher_credentials *c =
+      (grpc_oauth2_token_fetcher_credentials *)creds;
+  grpc_credentials_md_store_unref(c->access_token_md);
+  gpr_mu_destroy(&c->mu);
+  grpc_httpcli_context_destroy(&c->httpcli_context);
+}
+
+grpc_credentials_status
+grpc_oauth2_token_fetcher_credentials_parse_server_response(
+    const grpc_http_response *response, grpc_credentials_md_store **token_md,
+    gpr_timespec *token_lifetime) {
+  char *null_terminated_body = NULL;
+  char *new_access_token = NULL;
+  grpc_credentials_status status = GRPC_CREDENTIALS_OK;
+  grpc_json *json = NULL;
+
+  if (response == NULL) {
+    gpr_log(GPR_ERROR, "Received NULL response.");
+    status = GRPC_CREDENTIALS_ERROR;
+    goto end;
+  }
+
+  if (response->body_length > 0) {
+    null_terminated_body = gpr_malloc(response->body_length + 1);
+    null_terminated_body[response->body_length] = '\0';
+    memcpy(null_terminated_body, response->body, response->body_length);
+  }
+
+  if (response->status != 200) {
+    gpr_log(GPR_ERROR, "Call to http server ended with error %d [%s].",
+            response->status,
+            null_terminated_body != NULL ? null_terminated_body : "");
+    status = GRPC_CREDENTIALS_ERROR;
+    goto end;
+  } else {
+    grpc_json *access_token = NULL;
+    grpc_json *token_type = NULL;
+    grpc_json *expires_in = NULL;
+    grpc_json *ptr;
+    json = grpc_json_parse_string(null_terminated_body);
+    if (json == NULL) {
+      gpr_log(GPR_ERROR, "Could not parse JSON from %s", null_terminated_body);
+      status = GRPC_CREDENTIALS_ERROR;
+      goto end;
+    }
+    if (json->type != GRPC_JSON_OBJECT) {
+      gpr_log(GPR_ERROR, "Response should be a JSON object");
+      status = GRPC_CREDENTIALS_ERROR;
+      goto end;
+    }
+    for (ptr = json->child; ptr; ptr = ptr->next) {
+      if (strcmp(ptr->key, "access_token") == 0) {
+        access_token = ptr;
+      } else if (strcmp(ptr->key, "token_type") == 0) {
+        token_type = ptr;
+      } else if (strcmp(ptr->key, "expires_in") == 0) {
+        expires_in = ptr;
+      }
+    }
+    if (access_token == NULL || access_token->type != GRPC_JSON_STRING) {
+      gpr_log(GPR_ERROR, "Missing or invalid access_token in JSON.");
+      status = GRPC_CREDENTIALS_ERROR;
+      goto end;
+    }
+    if (token_type == NULL || token_type->type != GRPC_JSON_STRING) {
+      gpr_log(GPR_ERROR, "Missing or invalid token_type in JSON.");
+      status = GRPC_CREDENTIALS_ERROR;
+      goto end;
+    }
+    if (expires_in == NULL || expires_in->type != GRPC_JSON_NUMBER) {
+      gpr_log(GPR_ERROR, "Missing or invalid expires_in in JSON.");
+      status = GRPC_CREDENTIALS_ERROR;
+      goto end;
+    }
+    gpr_asprintf(&new_access_token, "%s %s", token_type->value,
+                 access_token->value);
+    token_lifetime->tv_sec = strtol(expires_in->value, NULL, 10);
+    token_lifetime->tv_nsec = 0;
+    token_lifetime->clock_type = GPR_TIMESPAN;
+    if (*token_md != NULL) grpc_credentials_md_store_unref(*token_md);
+    *token_md = grpc_credentials_md_store_create(1);
+    grpc_credentials_md_store_add_cstrings(
+        *token_md, GRPC_AUTHORIZATION_METADATA_KEY, new_access_token);
+    status = GRPC_CREDENTIALS_OK;
+  }
+
+end:
+  if (status != GRPC_CREDENTIALS_OK && (*token_md != NULL)) {
+    grpc_credentials_md_store_unref(*token_md);
+    *token_md = NULL;
+  }
+  if (null_terminated_body != NULL) gpr_free(null_terminated_body);
+  if (new_access_token != NULL) gpr_free(new_access_token);
+  if (json != NULL) grpc_json_destroy(json);
+  return status;
+}
+
+static void on_oauth2_token_fetcher_http_response(
+    grpc_exec_ctx *exec_ctx, void *user_data,
+    const grpc_http_response *response) {
+  grpc_credentials_metadata_request *r =
+      (grpc_credentials_metadata_request *)user_data;
+  grpc_oauth2_token_fetcher_credentials *c =
+      (grpc_oauth2_token_fetcher_credentials *)r->creds;
+  gpr_timespec token_lifetime;
+  grpc_credentials_status status;
+
+  gpr_mu_lock(&c->mu);
+  status = grpc_oauth2_token_fetcher_credentials_parse_server_response(
+      response, &c->access_token_md, &token_lifetime);
+  if (status == GRPC_CREDENTIALS_OK) {
+    c->token_expiration =
+        gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), token_lifetime);
+    r->cb(exec_ctx, r->user_data, c->access_token_md->entries,
+          c->access_token_md->num_entries, status, NULL);
+  } else {
+    c->token_expiration = gpr_inf_past(GPR_CLOCK_REALTIME);
+    r->cb(exec_ctx, r->user_data, NULL, 0, status, NULL);
+  }
+  gpr_mu_unlock(&c->mu);
+  grpc_credentials_metadata_request_destroy(r);
+}
+
+static void oauth2_token_fetcher_get_request_metadata(
+    grpc_exec_ctx *exec_ctx, grpc_call_credentials *creds,
+    grpc_pollset *pollset, grpc_auth_metadata_context context,
+    grpc_credentials_metadata_cb cb, void *user_data) {
+  grpc_oauth2_token_fetcher_credentials *c =
+      (grpc_oauth2_token_fetcher_credentials *)creds;
+  gpr_timespec refresh_threshold = gpr_time_from_seconds(
+      GRPC_SECURE_TOKEN_REFRESH_THRESHOLD_SECS, GPR_TIMESPAN);
+  grpc_credentials_md_store *cached_access_token_md = NULL;
+  {
+    gpr_mu_lock(&c->mu);
+    if (c->access_token_md != NULL &&
+        (gpr_time_cmp(
+             gpr_time_sub(c->token_expiration, gpr_now(GPR_CLOCK_REALTIME)),
+             refresh_threshold) > 0)) {
+      cached_access_token_md =
+          grpc_credentials_md_store_ref(c->access_token_md);
+    }
+    gpr_mu_unlock(&c->mu);
+  }
+  if (cached_access_token_md != NULL) {
+    cb(exec_ctx, user_data, cached_access_token_md->entries,
+       cached_access_token_md->num_entries, GRPC_CREDENTIALS_OK, NULL);
+    grpc_credentials_md_store_unref(cached_access_token_md);
+  } else {
+    c->fetch_func(
+        exec_ctx,
+        grpc_credentials_metadata_request_create(creds, cb, user_data),
+        &c->httpcli_context, pollset, on_oauth2_token_fetcher_http_response,
+        gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), refresh_threshold));
+  }
+}
+
+static void init_oauth2_token_fetcher(grpc_oauth2_token_fetcher_credentials *c,
+                                      grpc_fetch_oauth2_func fetch_func) {
+  memset(c, 0, sizeof(grpc_oauth2_token_fetcher_credentials));
+  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_OAUTH2;
+  gpr_ref_init(&c->base.refcount, 1);
+  gpr_mu_init(&c->mu);
+  c->token_expiration = gpr_inf_past(GPR_CLOCK_REALTIME);
+  c->fetch_func = fetch_func;
+  grpc_httpcli_context_init(&c->httpcli_context);
+}
+
+//
+//  Google Compute Engine credentials.
+//
+
+static grpc_call_credentials_vtable compute_engine_vtable = {
+    oauth2_token_fetcher_destruct, oauth2_token_fetcher_get_request_metadata};
+
+static void compute_engine_fetch_oauth2(
+    grpc_exec_ctx *exec_ctx, grpc_credentials_metadata_request *metadata_req,
+    grpc_httpcli_context *httpcli_context, grpc_pollset *pollset,
+    grpc_httpcli_response_cb response_cb, gpr_timespec deadline) {
+  grpc_http_header header = {"Metadata-Flavor", "Google"};
+  grpc_httpcli_request request;
+  memset(&request, 0, sizeof(grpc_httpcli_request));
+  request.host = GRPC_COMPUTE_ENGINE_METADATA_HOST;
+  request.http.path = GRPC_COMPUTE_ENGINE_METADATA_TOKEN_PATH;
+  request.http.hdr_count = 1;
+  request.http.hdrs = &header;
+  grpc_httpcli_get(exec_ctx, httpcli_context, pollset, &request, deadline,
+                   response_cb, metadata_req);
+}
+
+grpc_call_credentials *grpc_google_compute_engine_credentials_create(
+    void *reserved) {
+  grpc_oauth2_token_fetcher_credentials *c =
+      gpr_malloc(sizeof(grpc_oauth2_token_fetcher_credentials));
+  GRPC_API_TRACE("grpc_compute_engine_credentials_create(reserved=%p)", 1,
+                 (reserved));
+  GPR_ASSERT(reserved == NULL);
+  init_oauth2_token_fetcher(c, compute_engine_fetch_oauth2);
+  c->base.vtable = &compute_engine_vtable;
+  return &c->base;
+}
+
+//
+// Google Refresh Token credentials.
+//
+
+static void refresh_token_destruct(grpc_call_credentials *creds) {
+  grpc_google_refresh_token_credentials *c =
+      (grpc_google_refresh_token_credentials *)creds;
+  grpc_auth_refresh_token_destruct(&c->refresh_token);
+  oauth2_token_fetcher_destruct(&c->base.base);
+}
+
+static grpc_call_credentials_vtable refresh_token_vtable = {
+    refresh_token_destruct, oauth2_token_fetcher_get_request_metadata};
+
+static void refresh_token_fetch_oauth2(
+    grpc_exec_ctx *exec_ctx, grpc_credentials_metadata_request *metadata_req,
+    grpc_httpcli_context *httpcli_context, grpc_pollset *pollset,
+    grpc_httpcli_response_cb response_cb, gpr_timespec deadline) {
+  grpc_google_refresh_token_credentials *c =
+      (grpc_google_refresh_token_credentials *)metadata_req->creds;
+  grpc_http_header header = {"Content-Type",
+                             "application/x-www-form-urlencoded"};
+  grpc_httpcli_request request;
+  char *body = NULL;
+  gpr_asprintf(&body, GRPC_REFRESH_TOKEN_POST_BODY_FORMAT_STRING,
+               c->refresh_token.client_id, c->refresh_token.client_secret,
+               c->refresh_token.refresh_token);
+  memset(&request, 0, sizeof(grpc_httpcli_request));
+  request.host = GRPC_GOOGLE_OAUTH2_SERVICE_HOST;
+  request.http.path = GRPC_GOOGLE_OAUTH2_SERVICE_TOKEN_PATH;
+  request.http.hdr_count = 1;
+  request.http.hdrs = &header;
+  request.handshaker = &grpc_httpcli_ssl;
+  grpc_httpcli_post(exec_ctx, httpcli_context, pollset, &request, body,
+                    strlen(body), deadline, response_cb, metadata_req);
+  gpr_free(body);
+}
+
+grpc_call_credentials *
+grpc_refresh_token_credentials_create_from_auth_refresh_token(
+    grpc_auth_refresh_token refresh_token) {
+  grpc_google_refresh_token_credentials *c;
+  if (!grpc_auth_refresh_token_is_valid(&refresh_token)) {
+    gpr_log(GPR_ERROR, "Invalid input for refresh token credentials creation");
+    return NULL;
+  }
+  c = gpr_malloc(sizeof(grpc_google_refresh_token_credentials));
+  memset(c, 0, sizeof(grpc_google_refresh_token_credentials));
+  init_oauth2_token_fetcher(&c->base, refresh_token_fetch_oauth2);
+  c->base.base.vtable = &refresh_token_vtable;
+  c->refresh_token = refresh_token;
+  return &c->base.base;
+}
+
+grpc_call_credentials *grpc_google_refresh_token_credentials_create(
+    const char *json_refresh_token, void *reserved) {
+  GRPC_API_TRACE(
+      "grpc_refresh_token_credentials_create(json_refresh_token=%s, "
+      "reserved=%p)",
+      2, (json_refresh_token, reserved));
+  GPR_ASSERT(reserved == NULL);
+  return grpc_refresh_token_credentials_create_from_auth_refresh_token(
+      grpc_auth_refresh_token_create_from_string(json_refresh_token));
+}
+
+//
+// Oauth2 Access Token credentials.
+//
+
+static void access_token_destruct(grpc_call_credentials *creds) {
+  grpc_access_token_credentials *c = (grpc_access_token_credentials *)creds;
+  grpc_credentials_md_store_unref(c->access_token_md);
+}
+
+static void access_token_get_request_metadata(
+    grpc_exec_ctx *exec_ctx, grpc_call_credentials *creds,
+    grpc_pollset *pollset, grpc_auth_metadata_context context,
+    grpc_credentials_metadata_cb cb, void *user_data) {
+  grpc_access_token_credentials *c = (grpc_access_token_credentials *)creds;
+  cb(exec_ctx, user_data, c->access_token_md->entries, 1, GRPC_CREDENTIALS_OK,
+     NULL);
+}
+
+static grpc_call_credentials_vtable access_token_vtable = {
+    access_token_destruct, access_token_get_request_metadata};
+
+grpc_call_credentials *grpc_access_token_credentials_create(
+    const char *access_token, void *reserved) {
+  grpc_access_token_credentials *c =
+      gpr_malloc(sizeof(grpc_access_token_credentials));
+  char *token_md_value;
+  GRPC_API_TRACE(
+      "grpc_access_token_credentials_create(access_token=%s, "
+      "reserved=%p)",
+      2, (access_token, reserved));
+  GPR_ASSERT(reserved == NULL);
+  memset(c, 0, sizeof(grpc_access_token_credentials));
+  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_OAUTH2;
+  c->base.vtable = &access_token_vtable;
+  gpr_ref_init(&c->base.refcount, 1);
+  c->access_token_md = grpc_credentials_md_store_create(1);
+  gpr_asprintf(&token_md_value, "Bearer %s", access_token);
+  grpc_credentials_md_store_add_cstrings(
+      c->access_token_md, GRPC_AUTHORIZATION_METADATA_KEY, token_md_value);
+  gpr_free(token_md_value);
+  return &c->base;
+}
diff --git a/src/core/lib/security/credentials/oauth2/oauth2_credentials.h b/src/core/lib/security/credentials/oauth2/oauth2_credentials.h
new file mode 100644
index 0000000000..04915b333f
--- /dev/null
+++ b/src/core/lib/security/credentials/oauth2/oauth2_credentials.h
@@ -0,0 +1,109 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_SECURITY_CREDENTIALS_OAUTH2_OAUTH2_CREDENTIALS_H
+#define GRPC_CORE_LIB_SECURITY_CREDENTIALS_OAUTH2_OAUTH2_CREDENTIALS_H
+
+#include "src/core/lib/json/json.h"
+#include "src/core/lib/security/credentials/credentials.h"
+
+// auth_refresh_token parsing.
+typedef struct {
+  const char *type;
+  char *client_id;
+  char *client_secret;
+  char *refresh_token;
+} grpc_auth_refresh_token;
+
+/// Returns 1 if the object is valid, 0 otherwise.
+int grpc_auth_refresh_token_is_valid(
+    const grpc_auth_refresh_token *refresh_token);
+
+/// Creates a refresh token object from string. Returns an invalid object if a
+/// parsing error has been encountered.
+grpc_auth_refresh_token grpc_auth_refresh_token_create_from_string(
+    const char *json_string);
+
+/// Creates a refresh token object from parsed json. Returns an invalid object
+/// if a parsing error has been encountered.
+grpc_auth_refresh_token grpc_auth_refresh_token_create_from_json(
+    const grpc_json *json);
+
+/// Destructs the object.
+void grpc_auth_refresh_token_destruct(grpc_auth_refresh_token *refresh_token);
+
+// -- Oauth2 Token Fetcher credentials --
+//
+//  This object is a base for credentials that need to acquire an oauth2 token
+//  from an http service.
+
+typedef void (*grpc_fetch_oauth2_func)(grpc_exec_ctx *exec_ctx,
+                                       grpc_credentials_metadata_request *req,
+                                       grpc_httpcli_context *http_context,
+                                       grpc_pollset *pollset,
+                                       grpc_httpcli_response_cb response_cb,
+                                       gpr_timespec deadline);
+typedef struct {
+  grpc_call_credentials base;
+  gpr_mu mu;
+  grpc_credentials_md_store *access_token_md;
+  gpr_timespec token_expiration;
+  grpc_httpcli_context httpcli_context;
+  grpc_fetch_oauth2_func fetch_func;
+} grpc_oauth2_token_fetcher_credentials;
+
+// Google refresh token credentials.
+typedef struct {
+  grpc_oauth2_token_fetcher_credentials base;
+  grpc_auth_refresh_token refresh_token;
+} grpc_google_refresh_token_credentials;
+
+// Access token credentials.
+typedef struct {
+  grpc_call_credentials base;
+  grpc_credentials_md_store *access_token_md;
+} grpc_access_token_credentials;
+
+// Private constructor for refresh token credentials from an already parsed
+// refresh token. Takes ownership of the refresh token.
+grpc_call_credentials *
+grpc_refresh_token_credentials_create_from_auth_refresh_token(
+    grpc_auth_refresh_token token);
+
+// Exposed for testing only.
+grpc_credentials_status
+grpc_oauth2_token_fetcher_credentials_parse_server_response(
+    const struct grpc_http_response *response,
+    grpc_credentials_md_store **token_md, gpr_timespec *token_lifetime);
+
+#endif /* GRPC_CORE_LIB_SECURITY_CREDENTIALS_OAUTH2_OAUTH2_CREDENTIALS_H */
diff --git a/src/core/lib/security/credentials/plugin/plugin_credentials.c b/src/core/lib/security/credentials/plugin/plugin_credentials.c
new file mode 100644
index 0000000000..6397270305
--- /dev/null
+++ b/src/core/lib/security/credentials/plugin/plugin_credentials.c
@@ -0,0 +1,130 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/lib/security/credentials/plugin/plugin_credentials.h"
+
+#include <string.h>
+
+#include "src/core/lib/surface/api_trace.h"
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/sync.h>
+
+typedef struct {
+  void *user_data;
+  grpc_credentials_metadata_cb cb;
+} grpc_metadata_plugin_request;
+
+static void plugin_destruct(grpc_call_credentials *creds) {
+  grpc_plugin_credentials *c = (grpc_plugin_credentials *)creds;
+  if (c->plugin.state != NULL && c->plugin.destroy != NULL) {
+    c->plugin.destroy(c->plugin.state);
+  }
+}
+
+static void plugin_md_request_metadata_ready(void *request,
+                                             const grpc_metadata *md,
+                                             size_t num_md,
+                                             grpc_status_code status,
+                                             const char *error_details) {
+  /* called from application code */
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+  grpc_metadata_plugin_request *r = (grpc_metadata_plugin_request *)request;
+  if (status != GRPC_STATUS_OK) {
+    if (error_details != NULL) {
+      gpr_log(GPR_ERROR, "Getting metadata from plugin failed with error: %s",
+              error_details);
+    }
+    r->cb(&exec_ctx, r->user_data, NULL, 0, GRPC_CREDENTIALS_ERROR,
+          error_details);
+  } else {
+    size_t i;
+    grpc_credentials_md *md_array = NULL;
+    if (num_md > 0) {
+      md_array = gpr_malloc(num_md * sizeof(grpc_credentials_md));
+      for (i = 0; i < num_md; i++) {
+        md_array[i].key = gpr_slice_from_copied_string(md[i].key);
+        md_array[i].value =
+            gpr_slice_from_copied_buffer(md[i].value, md[i].value_length);
+      }
+    }
+    r->cb(&exec_ctx, r->user_data, md_array, num_md, GRPC_CREDENTIALS_OK, NULL);
+    if (md_array != NULL) {
+      for (i = 0; i < num_md; i++) {
+        gpr_slice_unref(md_array[i].key);
+        gpr_slice_unref(md_array[i].value);
+      }
+      gpr_free(md_array);
+    }
+  }
+  gpr_free(r);
+  grpc_exec_ctx_finish(&exec_ctx);
+}
+
+static void plugin_get_request_metadata(grpc_exec_ctx *exec_ctx,
+                                        grpc_call_credentials *creds,
+                                        grpc_pollset *pollset,
+                                        grpc_auth_metadata_context context,
+                                        grpc_credentials_metadata_cb cb,
+                                        void *user_data) {
+  grpc_plugin_credentials *c = (grpc_plugin_credentials *)creds;
+  if (c->plugin.get_metadata != NULL) {
+    grpc_metadata_plugin_request *request = gpr_malloc(sizeof(*request));
+    memset(request, 0, sizeof(*request));
+    request->user_data = user_data;
+    request->cb = cb;
+    c->plugin.get_metadata(c->plugin.state, context,
+                           plugin_md_request_metadata_ready, request);
+  } else {
+    cb(exec_ctx, user_data, NULL, 0, GRPC_CREDENTIALS_OK, NULL);
+  }
+}
+
+static grpc_call_credentials_vtable plugin_vtable = {
+    plugin_destruct, plugin_get_request_metadata};
+
+grpc_call_credentials *grpc_metadata_credentials_create_from_plugin(
+    grpc_metadata_credentials_plugin plugin, void *reserved) {
+  grpc_plugin_credentials *c = gpr_malloc(sizeof(*c));
+  GRPC_API_TRACE("grpc_metadata_credentials_create_from_plugin(reserved=%p)", 1,
+                 (reserved));
+  GPR_ASSERT(reserved == NULL);
+  memset(c, 0, sizeof(*c));
+  c->base.type = plugin.type;
+  c->base.vtable = &plugin_vtable;
+  gpr_ref_init(&c->base.refcount, 1);
+  c->plugin = plugin;
+  return &c->base;
+}
diff --git a/src/core/lib/security/credentials/plugin/plugin_credentials.h b/src/core/lib/security/credentials/plugin/plugin_credentials.h
new file mode 100644
index 0000000000..89073cb3d1
--- /dev/null
+++ b/src/core/lib/security/credentials/plugin/plugin_credentials.h
@@ -0,0 +1,45 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_SECURITY_CREDENTIALS_PLUGIN_PLUGIN_CREDENTIALS_H
+#define GRPC_CORE_LIB_SECURITY_CREDENTIALS_PLUGIN_PLUGIN_CREDENTIALS_H
+
+#include "src/core/lib/security/credentials/credentials.h"
+
+typedef struct {
+  grpc_call_credentials base;
+  grpc_metadata_credentials_plugin plugin;
+  grpc_credentials_md_store *plugin_md;
+} grpc_plugin_credentials;
+
+#endif /* GRPC_CORE_LIB_SECURITY_CREDENTIALS_PLUGIN_PLUGIN_CREDENTIALS_H */
diff --git a/src/core/lib/security/credentials/ssl/ssl_credentials.c b/src/core/lib/security/credentials/ssl/ssl_credentials.c
new file mode 100644
index 0000000000..545bca9d98
--- /dev/null
+++ b/src/core/lib/security/credentials/ssl/ssl_credentials.c
@@ -0,0 +1,240 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/lib/security/credentials/ssl/ssl_credentials.h"
+
+#include <string.h>
+
+#include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/channel/http_client_filter.h"
+#include "src/core/lib/surface/api_trace.h"
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+
+//
+// Utils
+//
+
+static void ssl_copy_key_material(const char *input, unsigned char **output,
+                                  size_t *output_size) {
+  *output_size = strlen(input);
+  *output = gpr_malloc(*output_size);
+  memcpy(*output, input, *output_size);
+}
+
+//
+// SSL Channel Credentials.
+//
+
+static void ssl_destruct(grpc_channel_credentials *creds) {
+  grpc_ssl_credentials *c = (grpc_ssl_credentials *)creds;
+  if (c->config.pem_root_certs != NULL) gpr_free(c->config.pem_root_certs);
+  if (c->config.pem_private_key != NULL) gpr_free(c->config.pem_private_key);
+  if (c->config.pem_cert_chain != NULL) gpr_free(c->config.pem_cert_chain);
+}
+
+static grpc_security_status ssl_create_security_connector(
+    grpc_channel_credentials *creds, grpc_call_credentials *call_creds,
+    const char *target, const grpc_channel_args *args,
+    grpc_channel_security_connector **sc, grpc_channel_args **new_args) {
+  grpc_ssl_credentials *c = (grpc_ssl_credentials *)creds;
+  grpc_security_status status = GRPC_SECURITY_OK;
+  size_t i = 0;
+  const char *overridden_target_name = NULL;
+  grpc_arg new_arg;
+
+  for (i = 0; args && i < args->num_args; i++) {
+    grpc_arg *arg = &args->args[i];
+    if (strcmp(arg->key, GRPC_SSL_TARGET_NAME_OVERRIDE_ARG) == 0 &&
+        arg->type == GRPC_ARG_STRING) {
+      overridden_target_name = arg->value.string;
+      break;
+    }
+  }
+  status = grpc_ssl_channel_security_connector_create(
+      call_creds, &c->config, target, overridden_target_name, sc);
+  if (status != GRPC_SECURITY_OK) {
+    return status;
+  }
+  new_arg.type = GRPC_ARG_STRING;
+  new_arg.key = GRPC_ARG_HTTP2_SCHEME;
+  new_arg.value.string = "https";
+  *new_args = grpc_channel_args_copy_and_add(args, &new_arg, 1);
+  return status;
+}
+
+static grpc_channel_credentials_vtable ssl_vtable = {
+    ssl_destruct, ssl_create_security_connector};
+
+static void ssl_build_config(const char *pem_root_certs,
+                             grpc_ssl_pem_key_cert_pair *pem_key_cert_pair,
+                             grpc_ssl_config *config) {
+  if (pem_root_certs != NULL) {
+    ssl_copy_key_material(pem_root_certs, &config->pem_root_certs,
+                          &config->pem_root_certs_size);
+  }
+  if (pem_key_cert_pair != NULL) {
+    GPR_ASSERT(pem_key_cert_pair->private_key != NULL);
+    GPR_ASSERT(pem_key_cert_pair->cert_chain != NULL);
+    ssl_copy_key_material(pem_key_cert_pair->private_key,
+                          &config->pem_private_key,
+                          &config->pem_private_key_size);
+    ssl_copy_key_material(pem_key_cert_pair->cert_chain,
+                          &config->pem_cert_chain,
+                          &config->pem_cert_chain_size);
+  }
+}
+
+grpc_channel_credentials *grpc_ssl_credentials_create(
+    const char *pem_root_certs, grpc_ssl_pem_key_cert_pair *pem_key_cert_pair,
+    void *reserved) {
+  grpc_ssl_credentials *c = gpr_malloc(sizeof(grpc_ssl_credentials));
+  GRPC_API_TRACE(
+      "grpc_ssl_credentials_create(pem_root_certs=%s, "
+      "pem_key_cert_pair=%p, "
+      "reserved=%p)",
+      3, (pem_root_certs, pem_key_cert_pair, reserved));
+  GPR_ASSERT(reserved == NULL);
+  memset(c, 0, sizeof(grpc_ssl_credentials));
+  c->base.type = GRPC_CHANNEL_CREDENTIALS_TYPE_SSL;
+  c->base.vtable = &ssl_vtable;
+  gpr_ref_init(&c->base.refcount, 1);
+  ssl_build_config(pem_root_certs, pem_key_cert_pair, &c->config);
+  return &c->base;
+}
+
+//
+// SSL Server Credentials.
+//
+
+static void ssl_server_destruct(grpc_server_credentials *creds) {
+  grpc_ssl_server_credentials *c = (grpc_ssl_server_credentials *)creds;
+  size_t i;
+  for (i = 0; i < c->config.num_key_cert_pairs; i++) {
+    if (c->config.pem_private_keys[i] != NULL) {
+      gpr_free(c->config.pem_private_keys[i]);
+    }
+    if (c->config.pem_cert_chains[i] != NULL) {
+      gpr_free(c->config.pem_cert_chains[i]);
+    }
+  }
+  if (c->config.pem_private_keys != NULL) gpr_free(c->config.pem_private_keys);
+  if (c->config.pem_private_keys_sizes != NULL) {
+    gpr_free(c->config.pem_private_keys_sizes);
+  }
+  if (c->config.pem_cert_chains != NULL) gpr_free(c->config.pem_cert_chains);
+  if (c->config.pem_cert_chains_sizes != NULL) {
+    gpr_free(c->config.pem_cert_chains_sizes);
+  }
+  if (c->config.pem_root_certs != NULL) gpr_free(c->config.pem_root_certs);
+}
+
+static grpc_security_status ssl_server_create_security_connector(
+    grpc_server_credentials *creds, grpc_server_security_connector **sc) {
+  grpc_ssl_server_credentials *c = (grpc_ssl_server_credentials *)creds;
+  return grpc_ssl_server_security_connector_create(&c->config, sc);
+}
+
+static grpc_server_credentials_vtable ssl_server_vtable = {
+    ssl_server_destruct, ssl_server_create_security_connector};
+
+static void ssl_build_server_config(
+    const char *pem_root_certs, grpc_ssl_pem_key_cert_pair *pem_key_cert_pairs,
+    size_t num_key_cert_pairs,
+    grpc_ssl_client_certificate_request_type client_certificate_request,
+    grpc_ssl_server_config *config) {
+  size_t i;
+  config->client_certificate_request = client_certificate_request;
+  if (pem_root_certs != NULL) {
+    ssl_copy_key_material(pem_root_certs, &config->pem_root_certs,
+                          &config->pem_root_certs_size);
+  }
+  if (num_key_cert_pairs > 0) {
+    GPR_ASSERT(pem_key_cert_pairs != NULL);
+    config->pem_private_keys =
+        gpr_malloc(num_key_cert_pairs * sizeof(unsigned char *));
+    config->pem_cert_chains =
+        gpr_malloc(num_key_cert_pairs * sizeof(unsigned char *));
+    config->pem_private_keys_sizes =
+        gpr_malloc(num_key_cert_pairs * sizeof(size_t));
+    config->pem_cert_chains_sizes =
+        gpr_malloc(num_key_cert_pairs * sizeof(size_t));
+  }
+  config->num_key_cert_pairs = num_key_cert_pairs;
+  for (i = 0; i < num_key_cert_pairs; i++) {
+    GPR_ASSERT(pem_key_cert_pairs[i].private_key != NULL);
+    GPR_ASSERT(pem_key_cert_pairs[i].cert_chain != NULL);
+    ssl_copy_key_material(pem_key_cert_pairs[i].private_key,
+                          &config->pem_private_keys[i],
+                          &config->pem_private_keys_sizes[i]);
+    ssl_copy_key_material(pem_key_cert_pairs[i].cert_chain,
+                          &config->pem_cert_chains[i],
+                          &config->pem_cert_chains_sizes[i]);
+  }
+}
+
+grpc_server_credentials *grpc_ssl_server_credentials_create(
+    const char *pem_root_certs, grpc_ssl_pem_key_cert_pair *pem_key_cert_pairs,
+    size_t num_key_cert_pairs, int force_client_auth, void *reserved) {
+  return grpc_ssl_server_credentials_create_ex(
+      pem_root_certs, pem_key_cert_pairs, num_key_cert_pairs,
+      force_client_auth
+          ? GRPC_SSL_REQUEST_AND_REQUIRE_CLIENT_CERTIFICATE_AND_VERIFY
+          : GRPC_SSL_DONT_REQUEST_CLIENT_CERTIFICATE,
+      reserved);
+}
+
+grpc_server_credentials *grpc_ssl_server_credentials_create_ex(
+    const char *pem_root_certs, grpc_ssl_pem_key_cert_pair *pem_key_cert_pairs,
+    size_t num_key_cert_pairs,
+    grpc_ssl_client_certificate_request_type client_certificate_request,
+    void *reserved) {
+  grpc_ssl_server_credentials *c =
+      gpr_malloc(sizeof(grpc_ssl_server_credentials));
+  GRPC_API_TRACE(
+      "grpc_ssl_server_credentials_create_ex("
+      "pem_root_certs=%s, pem_key_cert_pairs=%p, num_key_cert_pairs=%lu, "
+      "client_certificate_request=%d, reserved=%p)",
+      5, (pem_root_certs, pem_key_cert_pairs, (unsigned long)num_key_cert_pairs,
+          client_certificate_request, reserved));
+  GPR_ASSERT(reserved == NULL);
+  memset(c, 0, sizeof(grpc_ssl_server_credentials));
+  c->base.type = GRPC_CHANNEL_CREDENTIALS_TYPE_SSL;
+  gpr_ref_init(&c->base.refcount, 1);
+  c->base.vtable = &ssl_server_vtable;
+  ssl_build_server_config(pem_root_certs, pem_key_cert_pairs,
+                          num_key_cert_pairs, client_certificate_request,
+                          &c->config);
+  return &c->base;
+}
diff --git a/src/core/lib/security/credentials/ssl/ssl_credentials.h b/src/core/lib/security/credentials/ssl/ssl_credentials.h
new file mode 100644
index 0000000000..f23dbdbe49
--- /dev/null
+++ b/src/core/lib/security/credentials/ssl/ssl_credentials.h
@@ -0,0 +1,48 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+#ifndef GRPC_CORE_LIB_SECURITY_CREDENTIALS_SSL_SSL_CREDENTIALS_H
+#define GRPC_CORE_LIB_SECURITY_CREDENTIALS_SSL_SSL_CREDENTIALS_H
+
+#include "src/core/lib/security/credentials/credentials.h"
+
+typedef struct {
+  grpc_channel_credentials base;
+  grpc_ssl_config config;
+} grpc_ssl_credentials;
+
+typedef struct {
+  grpc_server_credentials base;
+  grpc_ssl_server_config config;
+} grpc_ssl_server_credentials;
+
+#endif /* GRPC_CORE_LIB_SECURITY_CREDENTIALS_SSL_SSL_CREDENTIALS_H */
diff --git a/src/core/lib/security/auth_filters.h b/src/core/lib/security/transport/auth_filters.h
index 7fb56c3f3a..f688d4ed21 100644
--- a/src/core/lib/security/auth_filters.h
+++ b/src/core/lib/security/transport/auth_filters.h
@@ -31,12 +31,12 @@
  *
  */
 
-#ifndef GRPC_CORE_LIB_SECURITY_AUTH_FILTERS_H
-#define GRPC_CORE_LIB_SECURITY_AUTH_FILTERS_H
+#ifndef GRPC_CORE_LIB_SECURITY_TRANSPORT_AUTH_FILTERS_H
+#define GRPC_CORE_LIB_SECURITY_TRANSPORT_AUTH_FILTERS_H
 
 #include "src/core/lib/channel/channel_stack.h"
 
 extern const grpc_channel_filter grpc_client_auth_filter;
 extern const grpc_channel_filter grpc_server_auth_filter;
 
-#endif /* GRPC_CORE_LIB_SECURITY_AUTH_FILTERS_H */
+#endif /* GRPC_CORE_LIB_SECURITY_TRANSPORT_AUTH_FILTERS_H */
diff --git a/src/core/lib/security/client_auth_filter.c b/src/core/lib/security/transport/client_auth_filter.c
index 3908b734a2..0a3f0cd008 100644
--- a/src/core/lib/security/client_auth_filter.c
+++ b/src/core/lib/security/transport/client_auth_filter.c
@@ -31,7 +31,7 @@
  *
  */
 
-#include "src/core/lib/security/auth_filters.h"
+#include "src/core/lib/security/transport/auth_filters.h"
 
 #include <string.h>
 
@@ -40,9 +40,9 @@
 #include <grpc/support/string_util.h>
 
 #include "src/core/lib/channel/channel_stack.h"
-#include "src/core/lib/security/credentials.h"
-#include "src/core/lib/security/security_connector.h"
-#include "src/core/lib/security/security_context.h"
+#include "src/core/lib/security/context/security_context.h"
+#include "src/core/lib/security/credentials/credentials.h"
+#include "src/core/lib/security/transport/security_connector.h"
 #include "src/core/lib/support/string.h"
 #include "src/core/lib/surface/call.h"
 #include "src/core/lib/transport/static_metadata.h"
@@ -282,7 +282,7 @@ static void set_pollset(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
 
 /* Destructor for call_data */
 static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                              void *ignored) {
+                              const grpc_call_stats *stats, void *ignored) {
   call_data *calld = elem->call_data;
   grpc_call_credentials_unref(calld->creds);
   if (calld->host != NULL) {
diff --git a/src/core/lib/security/handshake.c b/src/core/lib/security/transport/handshake.c
index d5fe0c7b7d..6561f4b47d 100644
--- a/src/core/lib/security/handshake.c
+++ b/src/core/lib/security/transport/handshake.c
@@ -31,7 +31,7 @@
  *
  */
 
-#include "src/core/lib/security/handshake.h"
+#include "src/core/lib/security/transport/handshake.h"
 
 #include <stdbool.h>
 #include <string.h>
@@ -39,8 +39,8 @@
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/slice_buffer.h>
-#include "src/core/lib/security/secure_endpoint.h"
-#include "src/core/lib/security/security_context.h"
+#include "src/core/lib/security/context/security_context.h"
+#include "src/core/lib/security/transport/secure_endpoint.h"
 
 #define GRPC_INITIAL_HANDSHAKE_BUFFER_SIZE 256
 
diff --git a/src/core/lib/security/handshake.h b/src/core/lib/security/transport/handshake.h
index f34476ed49..6ed850b315 100644
--- a/src/core/lib/security/handshake.h
+++ b/src/core/lib/security/transport/handshake.h
@@ -31,11 +31,11 @@
  *
  */
 
-#ifndef GRPC_CORE_LIB_SECURITY_HANDSHAKE_H
-#define GRPC_CORE_LIB_SECURITY_HANDSHAKE_H
+#ifndef GRPC_CORE_LIB_SECURITY_TRANSPORT_HANDSHAKE_H
+#define GRPC_CORE_LIB_SECURITY_TRANSPORT_HANDSHAKE_H
 
 #include "src/core/lib/iomgr/endpoint.h"
-#include "src/core/lib/security/security_connector.h"
+#include "src/core/lib/security/transport/security_connector.h"
 
 /* Calls the callback upon completion. Takes owership of handshaker. */
 void grpc_do_security_handshake(grpc_exec_ctx *exec_ctx,
@@ -48,4 +48,4 @@ void grpc_do_security_handshake(grpc_exec_ctx *exec_ctx,
 
 void grpc_security_handshake_shutdown(grpc_exec_ctx *exec_ctx, void *handshake);
 
-#endif /* GRPC_CORE_LIB_SECURITY_HANDSHAKE_H */
+#endif /* GRPC_CORE_LIB_SECURITY_TRANSPORT_HANDSHAKE_H */
diff --git a/src/core/lib/security/secure_endpoint.c b/src/core/lib/security/transport/secure_endpoint.c
index 27b0e98910..4438c8e559 100644
--- a/src/core/lib/security/secure_endpoint.c
+++ b/src/core/lib/security/transport/secure_endpoint.c
@@ -31,7 +31,7 @@
  *
  */
 
-#include "src/core/lib/security/secure_endpoint.h"
+#include "src/core/lib/security/transport/secure_endpoint.h"
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/slice.h>
diff --git a/src/core/lib/security/secure_endpoint.h b/src/core/lib/security/transport/secure_endpoint.h
index ff1c6639de..d00075b769 100644
--- a/src/core/lib/security/secure_endpoint.h
+++ b/src/core/lib/security/transport/secure_endpoint.h
@@ -31,8 +31,8 @@
  *
  */
 
-#ifndef GRPC_CORE_LIB_SECURITY_SECURE_ENDPOINT_H
-#define GRPC_CORE_LIB_SECURITY_SECURE_ENDPOINT_H
+#ifndef GRPC_CORE_LIB_SECURITY_TRANSPORT_SECURE_ENDPOINT_H
+#define GRPC_CORE_LIB_SECURITY_TRANSPORT_SECURE_ENDPOINT_H
 
 #include <grpc/support/slice.h>
 #include "src/core/lib/iomgr/endpoint.h"
@@ -46,4 +46,4 @@ grpc_endpoint *grpc_secure_endpoint_create(
     struct tsi_frame_protector *protector, grpc_endpoint *to_wrap,
     gpr_slice *leftover_slices, size_t leftover_nslices);
 
-#endif /* GRPC_CORE_LIB_SECURITY_SECURE_ENDPOINT_H */
+#endif /* GRPC_CORE_LIB_SECURITY_TRANSPORT_SECURE_ENDPOINT_H */
diff --git a/src/core/lib/security/security_connector.c b/src/core/lib/security/transport/security_connector.c
index 2d2023bdf5..72173e7c9d 100644
--- a/src/core/lib/security/security_connector.c
+++ b/src/core/lib/security/transport/security_connector.c
@@ -31,7 +31,7 @@
  *
  */
 
-#include "src/core/lib/security/security_connector.h"
+#include "src/core/lib/security/transport/security_connector.h"
 
 #include <stdbool.h>
 #include <string.h>
@@ -43,10 +43,10 @@
 #include <grpc/support/string_util.h>
 
 #include "src/core/ext/transport/chttp2/alpn/alpn.h"
-#include "src/core/lib/security/credentials.h"
-#include "src/core/lib/security/handshake.h"
-#include "src/core/lib/security/secure_endpoint.h"
-#include "src/core/lib/security/security_context.h"
+#include "src/core/lib/security/context/security_context.h"
+#include "src/core/lib/security/credentials/credentials.h"
+#include "src/core/lib/security/transport/handshake.h"
+#include "src/core/lib/security/transport/secure_endpoint.h"
 #include "src/core/lib/support/env.h"
 #include "src/core/lib/support/load_file.h"
 #include "src/core/lib/support/string.h"
diff --git a/src/core/lib/security/security_connector.h b/src/core/lib/security/transport/security_connector.h
index 2c893cd5e9..84e586deaa 100644
--- a/src/core/lib/security/security_connector.h
+++ b/src/core/lib/security/transport/security_connector.h
@@ -31,8 +31,8 @@
  *
  */
 
-#ifndef GRPC_CORE_LIB_SECURITY_SECURITY_CONNECTOR_H
-#define GRPC_CORE_LIB_SECURITY_SECURITY_CONNECTOR_H
+#ifndef GRPC_CORE_LIB_SECURITY_TRANSPORT_SECURITY_CONNECTOR_H
+#define GRPC_CORE_LIB_SECURITY_TRANSPORT_SECURITY_CONNECTOR_H
 
 #include <grpc/grpc_security.h>
 #include "src/core/lib/iomgr/endpoint.h"
@@ -263,4 +263,4 @@ tsi_peer tsi_shallow_peer_from_ssl_auth_context(
     const grpc_auth_context *auth_context);
 void tsi_shallow_peer_destruct(tsi_peer *peer);
 
-#endif /* GRPC_CORE_LIB_SECURITY_SECURITY_CONNECTOR_H */
+#endif /* GRPC_CORE_LIB_SECURITY_TRANSPORT_SECURITY_CONNECTOR_H */
diff --git a/src/core/lib/security/server_auth_filter.c b/src/core/lib/security/transport/server_auth_filter.c
index 3320497d21..714e0adfc9 100644
--- a/src/core/lib/security/server_auth_filter.c
+++ b/src/core/lib/security/transport/server_auth_filter.c
@@ -33,9 +33,9 @@
 
 #include <string.h>
 
-#include "src/core/lib/security/auth_filters.h"
-#include "src/core/lib/security/credentials.h"
-#include "src/core/lib/security/security_context.h"
+#include "src/core/lib/security/context/security_context.h"
+#include "src/core/lib/security/credentials/credentials.h"
+#include "src/core/lib/security/transport/auth_filters.h"
 
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
@@ -225,7 +225,7 @@ static void set_pollset(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
 
 /* Destructor for call_data */
 static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                              void *ignored) {}
+                              const grpc_call_stats *stats, void *ignored) {}
 
 /* Constructor for channel_data */
 static void init_channel_elem(grpc_exec_ctx *exec_ctx,
diff --git a/src/core/lib/security/b64.c b/src/core/lib/security/util/b64.c
index 87f0e05280..9da42e4e73 100644
--- a/src/core/lib/security/b64.c
+++ b/src/core/lib/security/util/b64.c
@@ -31,7 +31,7 @@
  *
  */
 
-#include "src/core/lib/security/b64.h"
+#include "src/core/lib/security/util/b64.h"
 
 #include <stdint.h>
 #include <string.h>
diff --git a/src/core/lib/security/b64.h b/src/core/lib/security/util/b64.h
index c515e7af2c..6908095287 100644
--- a/src/core/lib/security/b64.h
+++ b/src/core/lib/security/util/b64.h
@@ -31,8 +31,8 @@
  *
  */
 
-#ifndef GRPC_CORE_LIB_SECURITY_B64_H
-#define GRPC_CORE_LIB_SECURITY_B64_H
+#ifndef GRPC_CORE_LIB_SECURITY_UTIL_B64_H
+#define GRPC_CORE_LIB_SECURITY_UTIL_B64_H
 
 #include <grpc/support/slice.h>
 
@@ -49,4 +49,4 @@ gpr_slice grpc_base64_decode(const char *b64, int url_safe);
 gpr_slice grpc_base64_decode_with_len(const char *b64, size_t b64_len,
                                       int url_safe);
 
-#endif /* GRPC_CORE_LIB_SECURITY_B64_H */
+#endif /* GRPC_CORE_LIB_SECURITY_UTIL_B64_H */
diff --git a/src/core/lib/security/util/json_util.c b/src/core/lib/security/util/json_util.c
new file mode 100644
index 0000000000..7eed039baa
--- /dev/null
+++ b/src/core/lib/security/util/json_util.c
@@ -0,0 +1,61 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/lib/security/util/json_util.h"
+
+#include <string.h>
+
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+
+const char *grpc_json_get_string_property(const grpc_json *json,
+                                          const char *prop_name) {
+  grpc_json *child;
+  for (child = json->child; child != NULL; child = child->next) {
+    if (strcmp(child->key, prop_name) == 0) break;
+  }
+  if (child == NULL || child->type != GRPC_JSON_STRING) {
+    gpr_log(GPR_ERROR, "Invalid or missing %s property.", prop_name);
+    return NULL;
+  }
+  return child->value;
+}
+
+bool grpc_copy_json_string_property(const grpc_json *json,
+                                    const char *prop_name,
+                                    char **copied_value) {
+  const char *prop_value = grpc_json_get_string_property(json, prop_name);
+  if (prop_value == NULL) return false;
+  *copied_value = gpr_strdup(prop_value);
+  return true;
+}
diff --git a/src/core/lib/security/util/json_util.h b/src/core/lib/security/util/json_util.h
new file mode 100644
index 0000000000..137900593f
--- /dev/null
+++ b/src/core/lib/security/util/json_util.h
@@ -0,0 +1,55 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_SECURITY_UTIL_JSON_UTIL_H
+#define GRPC_CORE_LIB_SECURITY_UTIL_JSON_UTIL_H
+
+#include <stdbool.h>
+
+#include "src/core/lib/json/json.h"
+
+// Constants.
+#define GRPC_AUTH_JSON_TYPE_INVALID "invalid"
+#define GRPC_AUTH_JSON_TYPE_SERVICE_ACCOUNT "service_account"
+#define GRPC_AUTH_JSON_TYPE_AUTHORIZED_USER "authorized_user"
+
+// Gets a child property from a json node.
+const char *grpc_json_get_string_property(const grpc_json *json,
+                                          const char *prop_name);
+
+// Copies the value of the json child property specified by prop_name.
+// Returns false if the property was not found.
+bool grpc_copy_json_string_property(const grpc_json *json,
+                                    const char *prop_name, char **copied_value);
+
+#endif /* GRPC_CORE_LIB_SECURITY_UTIL_JSON_UTIL_H */