1da327cd2SJung-uk Kim=pod 2da327cd2SJung-uk Kim 3da327cd2SJung-uk Kim=head1 NAME 4da327cd2SJung-uk Kim 5da327cd2SJung-uk KimCRYPTO_memcmp - Constant time memory comparison 6da327cd2SJung-uk Kim 7da327cd2SJung-uk Kim=head1 SYNOPSIS 8da327cd2SJung-uk Kim 9da327cd2SJung-uk Kim #include <openssl/crypto.h> 10da327cd2SJung-uk Kim 11da327cd2SJung-uk Kim int CRYPTO_memcmp(const void *a, const void *b, size_t len); 12da327cd2SJung-uk Kim 13da327cd2SJung-uk Kim=head1 DESCRIPTION 14da327cd2SJung-uk Kim 15da327cd2SJung-uk KimThe CRYPTO_memcmp function compares the B<len> bytes pointed to by B<a> and B<b> 16da327cd2SJung-uk Kimfor equality. 17da327cd2SJung-uk KimIt takes an amount of time dependent on B<len>, but independent of the 18da327cd2SJung-uk Kimcontents of the memory regions pointed to by B<a> and B<b>. 19da327cd2SJung-uk Kim 20da327cd2SJung-uk Kim=head1 RETURN VALUES 21da327cd2SJung-uk Kim 2258f35182SJung-uk KimCRYPTO_memcmp() returns 0 if the memory regions are equal and nonzero 23da327cd2SJung-uk Kimotherwise. 24da327cd2SJung-uk Kim 25da327cd2SJung-uk Kim=head1 NOTES 26da327cd2SJung-uk Kim 27da327cd2SJung-uk KimUnlike memcmp(2), this function cannot be used to order the two memory regions 2858f35182SJung-uk Kimas the return value when they differ is undefined, other than being nonzero. 29da327cd2SJung-uk Kim 30da327cd2SJung-uk Kim=head1 COPYRIGHT 31da327cd2SJung-uk Kim 32*b077aed3SPierre ProncheryCopyright 2019 The OpenSSL Project Authors. All Rights Reserved. 33da327cd2SJung-uk Kim 34da327cd2SJung-uk KimLicensed under the Apache License 2.0 (the "License"). You may not use 35da327cd2SJung-uk Kimthis file except in compliance with the License. You can obtain a copy 36da327cd2SJung-uk Kimin the file LICENSE in the source distribution or at 37da327cd2SJung-uk KimL<https://www.openssl.org/source/license.html>. 38da327cd2SJung-uk Kim 39da327cd2SJung-uk Kim=cut 40