Add SHA1 and MD5 to utils.

https://codereview.appspot.com/7071055/


git-svn-id: http://skia.googlecode.com/svn/trunk@7496 2bbb7eff-a529-9590-31e7-b0007b416f81

4 files changed, 628 insertions, 0 deletions

diff --git a/src/utils/SkMD5.cpp b/src/utils/SkMD5.cpp
new file mode 100644
index 0000000000..725ae55f3f
--- /dev/null
+++ b/src/utils/SkMD5.cpp
@@ -0,0 +1,252 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * The following code is based on the description in RFC 1321.
+ * http://www.ietf.org/rfc/rfc1321.txt
+ */
+
+#include "SkTypes.h"
+#include "SkMD5.h"
+#include <string.h>
+
+/** MD5 basic transformation. Transforms state based on block. */
+static void transform(uint32_t state[4], const uint8_t block[64]);
+
+/** Encodes input into output (4 little endian 32 bit values). */
+static void encode(uint8_t output[16], const uint32_t input[4]);
+
+/** Encodes input into output (little endian 64 bit value). */
+static void encode(uint8_t output[8], const uint64_t input);
+
+/** Decodes input (4 little endian 32 bit values) into storage, if required. */
+static const uint32_t* decode(uint32_t storage[16], const uint8_t input[64]);
+
+SkMD5::SkMD5() : byteCount(0) {
+    // These are magic numbers from the specification.
+    this->state[0] = 0x67452301;
+    this->state[1] = 0xefcdab89;
+    this->state[2] = 0x98badcfe;
+    this->state[3] = 0x10325476;
+}
+
+void SkMD5::update(const uint8_t* input, size_t inputLength) {
+    unsigned int bufferIndex = (unsigned int)(this->byteCount & 0x3F);
+    unsigned int bufferAvailable = 64 - bufferIndex;
+
+    unsigned int inputIndex;
+    if (inputLength >= bufferAvailable) {
+        if (bufferIndex) {
+            memcpy(&this->buffer[bufferIndex], input, bufferAvailable);
+            transform(this->state, this->buffer);
+            inputIndex = bufferAvailable;
+        } else {
+            inputIndex = 0;
+        }
+
+        for (; inputIndex + 63 < inputLength; inputIndex += 64) {
+            transform(this->state, &input[inputIndex]);
+        }
+
+        bufferIndex = 0;
+    } else {
+        inputIndex = 0;
+    }
+
+    memcpy(&this->buffer[bufferIndex], &input[inputIndex], inputLength - inputIndex);
+
+    this->byteCount += inputLength;
+}
+
+void SkMD5::finish(Digest& digest) {
+    // Get the number of bits before padding.
+    uint8_t bits[8];
+    encode(bits, this->byteCount << 3);
+
+    // Pad out to 56 mod 64.
+    unsigned int bufferIndex = (unsigned int)(this->byteCount & 0x3F);
+    unsigned int paddingLength = (bufferIndex < 56) ? (56 - bufferIndex) : (120 - bufferIndex);
+    static uint8_t PADDING[64] = {
+        0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+           0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+           0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+           0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    };
+    this->update(PADDING, paddingLength);
+
+    // Append length (length before padding, will cause final update).
+    this->update(bits, 8);
+
+    // Write out digest.
+    encode(digest.data, this->state);
+
+#if defined(SK_MD5_CLEAR_DATA)
+    // Clear state.
+    memset(this, 0, sizeof(*this));
+#endif
+}
+
+struct F { uint32_t operator()(uint32_t x, uint32_t y, uint32_t z) {
+    //return (x & y) | ((~x) & z);
+    return ((y ^ z) & x) ^ z; //equivelent but faster
+}};
+
+struct G { uint32_t operator()(uint32_t x, uint32_t y, uint32_t z) {
+    return (x & z) | (y & (~z));
+    //return ((x ^ y) & z) ^ y; //equivelent but slower
+}};
+
+struct H { uint32_t operator()(uint32_t x, uint32_t y, uint32_t z) {
+    return x ^ y ^ z;
+}};
+
+struct I { uint32_t operator()(uint32_t x, uint32_t y, uint32_t z) {
+    return y ^ (x | (~z));
+}};
+
+/** Rotates x left n bits. */
+static inline uint32_t rotate_left(uint32_t x, uint8_t n) {
+    return (x << n) | (x >> (32 - n));
+}
+
+template <typename T>
+static inline void operation(T operation, uint32_t& a, uint32_t b, uint32_t c, uint32_t d,
+                             uint32_t x, uint8_t s, uint32_t t) {
+    a = b + rotate_left(a + operation(b, c, d) + x + t, s);
+}
+
+static void transform(uint32_t state[4], const uint8_t block[64]) {
+    uint32_t a = state[0], b = state[1], c = state[2], d = state[3];
+
+    uint32_t storage[16];
+    const uint32_t* X = decode(storage, block);
+
+    // Round 1
+    operation(F(), a, b, c, d, X[ 0],  7, 0xd76aa478); // 1
+    operation(F(), d, a, b, c, X[ 1], 12, 0xe8c7b756); // 2
+    operation(F(), c, d, a, b, X[ 2], 17, 0x242070db); // 3
+    operation(F(), b, c, d, a, X[ 3], 22, 0xc1bdceee); // 4
+    operation(F(), a, b, c, d, X[ 4],  7, 0xf57c0faf); // 5
+    operation(F(), d, a, b, c, X[ 5], 12, 0x4787c62a); // 6
+    operation(F(), c, d, a, b, X[ 6], 17, 0xa8304613); // 7
+    operation(F(), b, c, d, a, X[ 7], 22, 0xfd469501); // 8
+    operation(F(), a, b, c, d, X[ 8],  7, 0x698098d8); // 9
+    operation(F(), d, a, b, c, X[ 9], 12, 0x8b44f7af); // 10
+    operation(F(), c, d, a, b, X[10], 17, 0xffff5bb1); // 11
+    operation(F(), b, c, d, a, X[11], 22, 0x895cd7be); // 12
+    operation(F(), a, b, c, d, X[12],  7, 0x6b901122); // 13
+    operation(F(), d, a, b, c, X[13], 12, 0xfd987193); // 14
+    operation(F(), c, d, a, b, X[14], 17, 0xa679438e); // 15
+    operation(F(), b, c, d, a, X[15], 22, 0x49b40821); // 16
+
+    // Round 2
+    operation(G(), a, b, c, d, X[ 1],  5, 0xf61e2562); // 17
+    operation(G(), d, a, b, c, X[ 6],  9, 0xc040b340); // 18
+    operation(G(), c, d, a, b, X[11], 14, 0x265e5a51); // 19
+    operation(G(), b, c, d, a, X[ 0], 20, 0xe9b6c7aa); // 20
+    operation(G(), a, b, c, d, X[ 5],  5, 0xd62f105d); // 21
+    operation(G(), d, a, b, c, X[10],  9,  0x2441453); // 22
+    operation(G(), c, d, a, b, X[15], 14, 0xd8a1e681); // 23
+    operation(G(), b, c, d, a, X[ 4], 20, 0xe7d3fbc8); // 24
+    operation(G(), a, b, c, d, X[ 9],  5, 0x21e1cde6); // 25
+    operation(G(), d, a, b, c, X[14],  9, 0xc33707d6); // 26
+    operation(G(), c, d, a, b, X[ 3], 14, 0xf4d50d87); // 27
+    operation(G(), b, c, d, a, X[ 8], 20, 0x455a14ed); // 28
+    operation(G(), a, b, c, d, X[13],  5, 0xa9e3e905); // 29
+    operation(G(), d, a, b, c, X[ 2],  9, 0xfcefa3f8); // 30
+    operation(G(), c, d, a, b, X[ 7], 14, 0x676f02d9); // 31
+    operation(G(), b, c, d, a, X[12], 20, 0x8d2a4c8a); // 32
+
+    // Round 3
+    operation(H(), a, b, c, d, X[ 5],  4, 0xfffa3942); // 33
+    operation(H(), d, a, b, c, X[ 8], 11, 0x8771f681); // 34
+    operation(H(), c, d, a, b, X[11], 16, 0x6d9d6122); // 35
+    operation(H(), b, c, d, a, X[14], 23, 0xfde5380c); // 36
+    operation(H(), a, b, c, d, X[ 1],  4, 0xa4beea44); // 37
+    operation(H(), d, a, b, c, X[ 4], 11, 0x4bdecfa9); // 38
+    operation(H(), c, d, a, b, X[ 7], 16, 0xf6bb4b60); // 39
+    operation(H(), b, c, d, a, X[10], 23, 0xbebfbc70); // 40
+    operation(H(), a, b, c, d, X[13],  4, 0x289b7ec6); // 41
+    operation(H(), d, a, b, c, X[ 0], 11, 0xeaa127fa); // 42
+    operation(H(), c, d, a, b, X[ 3], 16, 0xd4ef3085); // 43
+    operation(H(), b, c, d, a, X[ 6], 23,  0x4881d05); // 44
+    operation(H(), a, b, c, d, X[ 9],  4, 0xd9d4d039); // 45
+    operation(H(), d, a, b, c, X[12], 11, 0xe6db99e5); // 46
+    operation(H(), c, d, a, b, X[15], 16, 0x1fa27cf8); // 47
+    operation(H(), b, c, d, a, X[ 2], 23, 0xc4ac5665); // 48
+
+    // Round 4
+    operation(I(), a, b, c, d, X[ 0],  6, 0xf4292244); // 49
+    operation(I(), d, a, b, c, X[ 7], 10, 0x432aff97); // 50
+    operation(I(), c, d, a, b, X[14], 15, 0xab9423a7); // 51
+    operation(I(), b, c, d, a, X[ 5], 21, 0xfc93a039); // 52
+    operation(I(), a, b, c, d, X[12],  6, 0x655b59c3); // 53
+    operation(I(), d, a, b, c, X[ 3], 10, 0x8f0ccc92); // 54
+    operation(I(), c, d, a, b, X[10], 15, 0xffeff47d); // 55
+    operation(I(), b, c, d, a, X[ 1], 21, 0x85845dd1); // 56
+    operation(I(), a, b, c, d, X[ 8],  6, 0x6fa87e4f); // 57
+    operation(I(), d, a, b, c, X[15], 10, 0xfe2ce6e0); // 58
+    operation(I(), c, d, a, b, X[ 6], 15, 0xa3014314); // 59
+    operation(I(), b, c, d, a, X[13], 21, 0x4e0811a1); // 60
+    operation(I(), a, b, c, d, X[ 4],  6, 0xf7537e82); // 61
+    operation(I(), d, a, b, c, X[11], 10, 0xbd3af235); // 62
+    operation(I(), c, d, a, b, X[ 2], 15, 0x2ad7d2bb); // 63
+    operation(I(), b, c, d, a, X[ 9], 21, 0xeb86d391); // 64
+
+    state[0] += a;
+    state[1] += b;
+    state[2] += c;
+    state[3] += d;
+
+#if defined(SK_MD5_CLEAR_DATA)
+    // Clear sensitive information.
+    if (X == &storage) {
+        memset(storage, 0, sizeof(storage));
+    }
+#endif
+}
+
+static void encode(uint8_t output[16], const uint32_t input[4]) {
+    for (size_t i = 0, j = 0; i < 4; i++, j += 4) {
+        output[j  ] = (uint8_t) (input[i]        & 0xff);
+        output[j+1] = (uint8_t)((input[i] >>  8) & 0xff);
+        output[j+2] = (uint8_t)((input[i] >> 16) & 0xff);
+        output[j+3] = (uint8_t)((input[i] >> 24) & 0xff);
+    }
+}
+
+static void encode(uint8_t output[8], const uint64_t input) {
+    output[0] = (uint8_t) (input        & 0xff);
+    output[1] = (uint8_t)((input >>  8) & 0xff);
+    output[2] = (uint8_t)((input >> 16) & 0xff);
+    output[3] = (uint8_t)((input >> 24) & 0xff);
+    output[4] = (uint8_t)((input >> 32) & 0xff);
+    output[5] = (uint8_t)((input >> 40) & 0xff);
+    output[6] = (uint8_t)((input >> 48) & 0xff);
+    output[7] = (uint8_t)((input >> 56) & 0xff);
+}
+
+static inline bool is_aligned(const void *pointer, size_t byte_count) {
+    return reinterpret_cast<uintptr_t>(pointer) % byte_count == 0;
+}
+
+static const uint32_t* decode(uint32_t storage[16], const uint8_t input[64]) {
+#if defined(SK_CPU_LENDIAN) && defined(SK_CPU_FAST_UNALIGNED_ACCESS)
+   return reinterpret_cast<const uint32_t*>(input);
+#else
+#if defined(SK_CPU_LENDIAN)
+    if (is_aligned(input, 4)) {
+        return reinterpret_cast<const uint32_t*>(input);
+    }
+#endif
+    for (size_t i = 0, j = 0; j < 64; i++, j += 4) {
+        storage[i] =  ((uint32_t)input[j  ])        |
+                     (((uint32_t)input[j+1]) <<  8) |
+                     (((uint32_t)input[j+2]) << 16) |
+                     (((uint32_t)input[j+3]) << 24);
+    }
+    return storage;
+#endif
+}
diff --git a/src/utils/SkMD5.h b/src/utils/SkMD5.h
new file mode 100644
index 0000000000..23119e897c
--- /dev/null
+++ b/src/utils/SkMD5.h
@@ -0,0 +1,54 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkMD5_DEFINED
+#define SkMD5_DEFINED
+
+#include "SkTypes.h"
+#include "SkEndian.h"
+#include "SkStream.h"
+
+//The following macros can be defined to affect the MD5 code generated.
+//SK_MD5_CLEAR_DATA causes all intermediate state to be overwritten with 0's.
+//SK_CPU_LENDIAN allows 32 bit <=> 8 bit conversions without copies (if alligned).
+//SK_CPU_FAST_UNALIGNED_ACCESS allows 32 bit <=> 8 bit conversions without copies if SK_CPU_LENDIAN.
+
+class SkMD5 : SkWStream {
+public:
+    SkMD5();
+
+    /** Processes input, adding it to the digest.
+     *  Note that this treats the buffer as a series of uint8_t values.
+     */
+    virtual bool write(const void* buffer, size_t size) SK_OVERRIDE {
+        update(reinterpret_cast<const uint8_t*>(buffer), size);
+        return true;
+    }
+
+    /** Processes input, adding it to the digest. Calling this after finish is undefined. */
+    void update(const uint8_t* input, size_t length);
+
+    struct Digest {
+        uint8_t data[16];
+    };
+
+    /** Computes and returns the digest. */
+    void finish(Digest& digest);
+
+private:
+    // number of bytes, modulo 2^64
+    uint64_t byteCount;
+
+    // state (ABCD)
+    uint32_t state[4];
+
+    // input buffer
+    uint8_t buffer[64];
+};
+
+#endif
+
diff --git a/src/utils/SkSHA1.cpp b/src/utils/SkSHA1.cpp
new file mode 100644
index 0000000000..1abac0640e
--- /dev/null
+++ b/src/utils/SkSHA1.cpp
@@ -0,0 +1,268 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * The following code is based on the description in RFC 3174.
+ * http://www.ietf.org/rfc/rfc3174.txt
+ */
+
+#include "SkTypes.h"
+#include "SkSHA1.h"
+#include <string.h>
+
+/** SHA1 basic transformation. Transforms state based on block. */
+static void transform(uint32_t state[5], const uint8_t block[64]);
+
+/** Encodes input into output (5 big endian 32 bit values). */
+static void encode(uint8_t output[20], const uint32_t input[5]);
+
+/** Encodes input into output (big endian 64 bit value). */
+static void encode(uint8_t output[8], const uint64_t input);
+
+SkSHA1::SkSHA1() : byteCount(0) {
+    // These are magic numbers from the specification. The first four are the same as MD5.
+    this->state[0] = 0x67452301;
+    this->state[1] = 0xefcdab89;
+    this->state[2] = 0x98badcfe;
+    this->state[3] = 0x10325476;
+    this->state[4] = 0xc3d2e1f0;
+}
+
+void SkSHA1::update(const uint8_t* input, size_t inputLength) {
+    unsigned int bufferIndex = (unsigned int)(this->byteCount & 0x3F);
+    unsigned int bufferAvailable = 64 - bufferIndex;
+
+    unsigned int inputIndex;
+    if (inputLength >= bufferAvailable) {
+        if (bufferIndex) {
+            memcpy(&this->buffer[bufferIndex], input, bufferAvailable);
+            transform(this->state, this->buffer);
+            inputIndex = bufferAvailable;
+        } else {
+            inputIndex = 0;
+        }
+
+        for (; inputIndex + 63 < inputLength; inputIndex += 64) {
+            transform(this->state, &input[inputIndex]);
+        }
+
+        bufferIndex = 0;
+    } else {
+        inputIndex = 0;
+    }
+
+    memcpy(&this->buffer[bufferIndex], &input[inputIndex], inputLength - inputIndex);
+
+    this->byteCount += inputLength;
+}
+
+void SkSHA1::finish(Digest& digest) {
+    // Get the number of bits before padding.
+    uint8_t bits[8];
+    encode(bits, this->byteCount << 3);
+
+    // Pad out to 56 mod 64.
+    unsigned int bufferIndex = (unsigned int)(this->byteCount & 0x3F);
+    unsigned int paddingLength = (bufferIndex < 56) ? (56 - bufferIndex) : (120 - bufferIndex);
+    static uint8_t PADDING[64] = {
+        0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+           0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+           0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+           0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    };
+    this->update(PADDING, paddingLength);
+
+    // Append length (length before padding, will cause final update).
+    this->update(bits, 8);
+
+    // Write out digest.
+    encode(digest.data, this->state);
+
+#if defined(SK_SHA1_CLEAR_DATA)
+    // Clear state.
+    memset(this, 0, sizeof(*this));
+#endif
+}
+
+struct F1 { uint32_t operator()(uint32_t B, uint32_t C, uint32_t D) {
+    return (B & C) | ((~B) & D);
+    //return D ^ (B & (C ^ D));
+    //return (B & C) ^ ((~B) & D);
+    //return (B & C) + ((~B) & D);
+    //return _mm_or_ps(_mm_andnot_ps(B, D), _mm_and_ps(B, C)); //SSE2
+    //return vec_sel(D, C, B); //PPC
+}};
+
+struct F2 { uint32_t operator()(uint32_t B, uint32_t C, uint32_t D) {
+    return B ^ C ^ D;
+}};
+
+struct F3 { uint32_t operator()(uint32_t B, uint32_t C, uint32_t D) {
+    return (B & C) | (B & D) | (C & D);
+    //return (B & C) | (D & (B | C));
+    //return (B & C) | (D & (B ^ C));
+    //return (B & C) + (D & (B ^ C));
+    //return (B & C) ^ (B & D) ^ (C & D);
+}};
+
+/** Rotates x left n bits. */
+static inline uint32_t rotate_left(uint32_t x, uint8_t n) {
+    return (x << n) | (x >> (32 - n));
+}
+
+template <typename T>
+static inline void operation(T operation,
+                             uint32_t A, uint32_t& B, uint32_t C, uint32_t D, uint32_t& E,
+                             uint32_t w, uint32_t k) {
+    E += rotate_left(A, 5) + operation(B, C, D) + w + k;
+    B = rotate_left(B, 30);
+}
+
+static void transform(uint32_t state[5], const uint8_t block[64]) {
+    uint32_t A = state[0], B = state[1], C = state[2], D = state[3], E = state[4];
+
+    // Round constants defined in SHA-1.
+    static const uint32_t K[] = {
+        0x5A827999, //sqrt(2) * 2^30
+        0x6ED9EBA1, //sqrt(3) * 2^30
+        0x8F1BBCDC, //sqrt(5) * 2^30
+        0xCA62C1D6, //sqrt(10) * 2^30
+    };
+
+    uint32_t W[80];
+
+    // Initialize the array W.
+    size_t i = 0;
+    for (size_t j = 0; i < 16; ++i, j += 4) {
+        W[i] = (((uint32_t)block[j  ]) << 24) |
+               (((uint32_t)block[j+1]) << 16) |
+               (((uint32_t)block[j+2]) <<  8) |
+               (((uint32_t)block[j+3])      );
+    }
+    for (; i < 80; ++i) {
+       W[i] = rotate_left(W[i-3] ^ W[i-8] ^ W[i-14] ^ W[i-16], 1);
+       //The following is equivelent and speeds up SSE implementations, but slows non-SSE.
+       //W[i] = rotate_left(W[i-6] ^ W[i-16] ^ W[i-28] ^ W[i-32], 2);
+    }
+
+    // Round 1
+    operation(F1(), A, B, C, D, E, W[ 0], K[0]);
+    operation(F1(), E, A, B, C, D, W[ 1], K[0]);
+    operation(F1(), D, E, A, B, C, W[ 2], K[0]);
+    operation(F1(), C, D, E, A, B, W[ 3], K[0]);
+    operation(F1(), B, C, D, E, A, W[ 4], K[0]);
+    operation(F1(), A, B, C, D, E, W[ 5], K[0]);
+    operation(F1(), E, A, B, C, D, W[ 6], K[0]);
+    operation(F1(), D, E, A, B, C, W[ 7], K[0]);
+    operation(F1(), C, D, E, A, B, W[ 8], K[0]);
+    operation(F1(), B, C, D, E, A, W[ 9], K[0]);
+    operation(F1(), A, B, C, D, E, W[10], K[0]);
+    operation(F1(), E, A, B, C, D, W[11], K[0]);
+    operation(F1(), D, E, A, B, C, W[12], K[0]);
+    operation(F1(), C, D, E, A, B, W[13], K[0]);
+    operation(F1(), B, C, D, E, A, W[14], K[0]);
+    operation(F1(), A, B, C, D, E, W[15], K[0]);
+    operation(F1(), E, A, B, C, D, W[16], K[0]);
+    operation(F1(), D, E, A, B, C, W[17], K[0]);
+    operation(F1(), C, D, E, A, B, W[18], K[0]);
+    operation(F1(), B, C, D, E, A, W[19], K[0]);
+
+    // Round 2
+    operation(F2(), A, B, C, D, E, W[20], K[1]);
+    operation(F2(), E, A, B, C, D, W[21], K[1]);
+    operation(F2(), D, E, A, B, C, W[22], K[1]);
+    operation(F2(), C, D, E, A, B, W[23], K[1]);
+    operation(F2(), B, C, D, E, A, W[24], K[1]);
+    operation(F2(), A, B, C, D, E, W[25], K[1]);
+    operation(F2(), E, A, B, C, D, W[26], K[1]);
+    operation(F2(), D, E, A, B, C, W[27], K[1]);
+    operation(F2(), C, D, E, A, B, W[28], K[1]);
+    operation(F2(), B, C, D, E, A, W[29], K[1]);
+    operation(F2(), A, B, C, D, E, W[30], K[1]);
+    operation(F2(), E, A, B, C, D, W[31], K[1]);
+    operation(F2(), D, E, A, B, C, W[32], K[1]);
+    operation(F2(), C, D, E, A, B, W[33], K[1]);
+    operation(F2(), B, C, D, E, A, W[34], K[1]);
+    operation(F2(), A, B, C, D, E, W[35], K[1]);
+    operation(F2(), E, A, B, C, D, W[36], K[1]);
+    operation(F2(), D, E, A, B, C, W[37], K[1]);
+    operation(F2(), C, D, E, A, B, W[38], K[1]);
+    operation(F2(), B, C, D, E, A, W[39], K[1]);
+
+    // Round 3
+    operation(F3(), A, B, C, D, E, W[40], K[2]);
+    operation(F3(), E, A, B, C, D, W[41], K[2]);
+    operation(F3(), D, E, A, B, C, W[42], K[2]);
+    operation(F3(), C, D, E, A, B, W[43], K[2]);
+    operation(F3(), B, C, D, E, A, W[44], K[2]);
+    operation(F3(), A, B, C, D, E, W[45], K[2]);
+    operation(F3(), E, A, B, C, D, W[46], K[2]);
+    operation(F3(), D, E, A, B, C, W[47], K[2]);
+    operation(F3(), C, D, E, A, B, W[48], K[2]);
+    operation(F3(), B, C, D, E, A, W[49], K[2]);
+    operation(F3(), A, B, C, D, E, W[50], K[2]);
+    operation(F3(), E, A, B, C, D, W[51], K[2]);
+    operation(F3(), D, E, A, B, C, W[52], K[2]);
+    operation(F3(), C, D, E, A, B, W[53], K[2]);
+    operation(F3(), B, C, D, E, A, W[54], K[2]);
+    operation(F3(), A, B, C, D, E, W[55], K[2]);
+    operation(F3(), E, A, B, C, D, W[56], K[2]);
+    operation(F3(), D, E, A, B, C, W[57], K[2]);
+    operation(F3(), C, D, E, A, B, W[58], K[2]);
+    operation(F3(), B, C, D, E, A, W[59], K[2]);
+
+    // Round 4
+    operation(F2(), A, B, C, D, E, W[60], K[3]);
+    operation(F2(), E, A, B, C, D, W[61], K[3]);
+    operation(F2(), D, E, A, B, C, W[62], K[3]);
+    operation(F2(), C, D, E, A, B, W[63], K[3]);
+    operation(F2(), B, C, D, E, A, W[64], K[3]);
+    operation(F2(), A, B, C, D, E, W[65], K[3]);
+    operation(F2(), E, A, B, C, D, W[66], K[3]);
+    operation(F2(), D, E, A, B, C, W[67], K[3]);
+    operation(F2(), C, D, E, A, B, W[68], K[3]);
+    operation(F2(), B, C, D, E, A, W[69], K[3]);
+    operation(F2(), A, B, C, D, E, W[70], K[3]);
+    operation(F2(), E, A, B, C, D, W[71], K[3]);
+    operation(F2(), D, E, A, B, C, W[72], K[3]);
+    operation(F2(), C, D, E, A, B, W[73], K[3]);
+    operation(F2(), B, C, D, E, A, W[74], K[3]);
+    operation(F2(), A, B, C, D, E, W[75], K[3]);
+    operation(F2(), E, A, B, C, D, W[76], K[3]);
+    operation(F2(), D, E, A, B, C, W[77], K[3]);
+    operation(F2(), C, D, E, A, B, W[78], K[3]);
+    operation(F2(), B, C, D, E, A, W[79], K[3]);
+
+    state[0] += A;
+    state[1] += B;
+    state[2] += C;
+    state[3] += D;
+    state[4] += E;
+
+#if defined(SK_SHA1_CLEAR_DATA)
+    // Clear sensitive information.
+    memset(W, 0, sizeof(W));
+#endif
+}
+
+static void encode(uint8_t output[20], const uint32_t input[5]) {
+    for (size_t i = 0, j = 0; i < 5; i++, j += 4) {
+        output[j  ] = (uint8_t)((input[i] >> 24) & 0xff);
+        output[j+1] = (uint8_t)((input[i] >> 16) & 0xff);
+        output[j+2] = (uint8_t)((input[i] >>  8) & 0xff);
+        output[j+3] = (uint8_t)((input[i]      ) & 0xff);
+    }
+}
+
+static void encode(uint8_t output[8], const uint64_t input) {
+    output[0] = (uint8_t)((input >> 56) & 0xff);
+    output[1] = (uint8_t)((input >> 48) & 0xff);
+    output[2] = (uint8_t)((input >> 40) & 0xff);
+    output[3] = (uint8_t)((input >> 32) & 0xff);
+    output[4] = (uint8_t)((input >> 24) & 0xff);
+    output[5] = (uint8_t)((input >> 16) & 0xff);
+    output[6] = (uint8_t)((input >>  8) & 0xff);
+    output[7] = (uint8_t)((input      ) & 0xff);
+}
diff --git a/src/utils/SkSHA1.h b/src/utils/SkSHA1.h
new file mode 100644
index 0000000000..e0653c62e6
--- /dev/null
+++ b/src/utils/SkSHA1.h
@@ -0,0 +1,54 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkSHA1_DEFINED
+#define SkSHA1_DEFINED
+
+#include "SkTypes.h"
+#include "SkEndian.h"
+#include "SkStream.h"
+
+//The following macros can be defined to affect the SHA1 code generated.
+//SK_SHA1_CLEAR_DATA causes all intermediate state to be overwritten with 0's.
+//SK_CPU_BENDIAN allows 32 bit <=> 8 bit conversions without copies (if alligned).
+//SK_CPU_FAST_UNALIGNED_ACCESS allows 32 bit <=> 8 bit conversions without copies if SK_CPU_BENDIAN.
+
+class SkSHA1 : SkWStream {
+public:
+    SkSHA1();
+
+    /** Processes input, adding it to the digest.
+     *  Note that this treats the buffer as a series of uint8_t values.
+     */
+    virtual bool write(const void* buffer, size_t size) SK_OVERRIDE {
+        update(reinterpret_cast<const uint8_t*>(buffer), size);
+        return true;
+    }
+
+    /** Processes input, adding it to the digest. Calling this after finish is undefined. */
+    void update(const uint8_t* input, size_t length);
+
+    struct Digest {
+        uint8_t data[20];
+    };
+
+    /** Computes and returns the digest. */
+    void finish(Digest& digest);
+
+private:
+    // number of bytes, modulo 2^64
+    uint64_t byteCount;
+
+    // state (ABCDE)
+    uint32_t state[5];
+
+    // input buffer
+    uint8_t buffer[64];
+};
+
+#endif
+