From 3be302655bc7e31805af4525d78beb6abfed9a5d Mon Sep 17 00:00:00 2001
From: Benjamin Barenblat <bbaren@google.com>
Date: Thu, 23 Aug 2018 14:59:32 -0400
Subject: Wrap random number generator

---
 src/System/Random/Crypto.hs | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 src/System/Random/Crypto.hs

(limited to 'src/System/Random/Crypto.hs')

diff --git a/src/System/Random/Crypto.hs b/src/System/Random/Crypto.hs
new file mode 100644
index 0000000..ca2fba5
--- /dev/null
+++ b/src/System/Random/Crypto.hs
@@ -0,0 +1,31 @@
+-- Copyright 2018 Google LLC
+--
+-- Licensed under the Apache License, Version 2.0 (the "License"); you may not
+-- use this file except in compliance with the License. You may obtain a copy of
+-- the License at
+--
+--     https://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing, software
+-- distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+-- WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+-- License for the specific language governing permissions and limitations under
+-- the License.
+
+module System.Random.Crypto
+  ( randomBytes
+  ) where
+
+import Data.ByteString (ByteString)
+import qualified Data.ByteString as ByteString
+import Foreign (allocaArray)
+
+import BTLS.BoringSSL.Rand (randBytes)
+import BTLS.Cast (asCUCharBuf)
+
+-- | Generates a cryptographically random buffer of the specified size.
+randomBytes :: Int -> IO ByteString
+randomBytes len =
+  allocaArray len $ \pBuf -> do
+    randBytes (asCUCharBuf pBuf) (fromIntegral len)
+    ByteString.packCStringLen (pBuf, len)
-- 
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