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/**
* Constant-time functions
*/
/*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
*/
#ifndef MBEDTLS_CONSTANT_TIME_H
#define MBEDTLS_CONSTANT_TIME_H
#include <stddef.h>
/** Constant-time buffer comparison without branches.
*
* This is equivalent to the standard memcmp function, but is likely to be
* compiled to code using bitwise operations rather than a branch, such that
* the time taken is constant w.r.t. the data pointed to by \p a and \p b,
* and w.r.t. whether \p a and \p b are equal or not. It is not constant-time
* w.r.t. \p n .
*
* This function can be used to write constant-time code by replacing branches
* with bit operations using masks.
*
* \param a Pointer to the first buffer, containing at least \p n bytes. May not be NULL.
* \param b Pointer to the second buffer, containing at least \p n bytes. May not be NULL.
* \param n The number of bytes to compare.
*
* \return Zero if the contents of the two buffers are the same,
* otherwise non-zero.
*/
int mbedtls_ct_memcmp(const void *a,
const void *b,
size_t n);
#endif /* MBEDTLS_CONSTANT_TIME_H */
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