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diff --git a/src/System/Random/Crypto.hs b/src/System/Random/Crypto.hs
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+-- 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)