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A collection of utility functions for cryptographic purposes.
============================================================================
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
Go to the source code of this file.
Functions | |
bool | CryptoUtils_buffersMatch (const void *buffer0, const void *buffer1, size_t bufferByteLength) |
Compares two buffers for equality without branching. More... | |
bool | CryptoUtils_buffersMatchWordAligned (const uint32_t *buffer0, const uint32_t *buffer1, size_t bufferByteLength) |
Compares two buffers for equality word-by-word without branching. More... | |
bool CryptoUtils_buffersMatch | ( | const void * | buffer0, |
const void * | buffer1, | ||
size_t | bufferByteLength | ||
) |
Compares two buffers for equality without branching.
Most memcmp implementations break out of their comparison loop immediately once a mismatch is detected to save execution time. For cryptographic purposes, this is a flaw.
This function compares two buffers without branching thus requiring a an amount of time that does not vary with the content of buffer0
and buffer1
.
buffer0 | Buffer to compare against buffer1 . |
buffer1 | Buffer tp compare against buffer0 |
bufferByteLength | Length in bytes of buffer0 and buffer1 . |
true | The contents of the buffers match. |
false | The contents of the buffers do not match. |
bool CryptoUtils_buffersMatchWordAligned | ( | const uint32_t * | buffer0, |
const uint32_t * | buffer1, | ||
size_t | bufferByteLength | ||
) |
Compares two buffers for equality word-by-word without branching.
Most memcmp implementations break out of their comparison loop immediately once a mismatch is detected to save execution time. For cryptographic purposes, this is a flaw.
This function compares two buffers without branching thus requiring a an amount of time that does not vary with the content of buffer0
and buffer1
.
Unlike CryptoUtils_buffersMatch(), this function expects buffer0
and buffer1
to be 32-bit aligned. It will only perform 32-bit aligned accesses to memory. This is needed to access the registers of certain peripherals.
buffer0 | Buffer to compare against buffer1 . |
buffer1 | Buffer tp compare against buffer0 |
bufferByteLength | Length in bytes of buffer0 and buffer1 . Must be evenly divisible by sizeof(uint32_t). This function will return false if bufferByteLength is not evenly divisible by sizeof(uin32_t). |
true | The contents of the buffers match. |
false | The contents of the buffers do not match. |