From 2152e7728db7e0cf86ea23d29a05294af24b6898 Mon Sep 17 00:00:00 2001 From: Benjamin Barenblat Date: Thu, 2 Aug 2018 17:08:44 -0400 Subject: Begin cleaning up internal modules Clarify the division between internal and external modules in the source by consolidating all internal modules except Data.Digest.Internal into a flatter BTLS directory. --- src/BTLS/ConstantTimeEquals.chs | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) create mode 100644 src/BTLS/ConstantTimeEquals.chs (limited to 'src/BTLS/ConstantTimeEquals.chs') diff --git a/src/BTLS/ConstantTimeEquals.chs b/src/BTLS/ConstantTimeEquals.chs new file mode 100644 index 0000000..77b1af0 --- /dev/null +++ b/src/BTLS/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 BTLS.ConstantTimeEquals where + +import Foreign (Ptr) +import Foreign.C.Types + +import BTLS.Cast (asVoidPtr) + +#include + +-- | 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' -- cgit v1.2.3