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Diffstat (limited to 'src/Foreign/Ptr/ConstantTimeEquals.chs')
-rw-r--r-- | src/Foreign/Ptr/ConstantTimeEquals.chs | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/src/Foreign/Ptr/ConstantTimeEquals.chs b/src/Foreign/Ptr/ConstantTimeEquals.chs new file mode 100644 index 0000000..6b34e7b --- /dev/null +++ b/src/Foreign/Ptr/ConstantTimeEquals.chs @@ -0,0 +1,30 @@ +-- 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 Foreign.Ptr.ConstantTimeEquals where + +import Foreign (Ptr) +import Foreign.C.Types + +import Foreign.Ptr.Cast (asVoidPtr) + +#include <openssl/mem.h> + +-- | Directly compares two buffers for equality. This operation takes an amount +-- of time dependent on the specified size but independent of either buffer's +-- contents. +constantTimeEquals :: Ptr a -> Ptr a -> Int -> IO Bool +constantTimeEquals a b size = + let size' = fromIntegral size :: CULong + in (== 0) <$> {#call CRYPTO_memcmp as ^#} (asVoidPtr a) (asVoidPtr b) size' |