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=head1 NAME

CRYPTO_memcmp - Constant time memory comparison

=head1 SYNOPSIS

 #include <openssl/crypto.h>

 int CRYPTO_memcmp(const void *a, const void *b, size_t len);

=head1 DESCRIPTION

The CRYPTO_memcmp function compares the B<len> bytes pointed to by B<a> and B<b>
for equality.
It takes an amount of time dependent on B<len>, but independent of the
contents of the memory regions pointed to by B<a> and B<b>.

=head1 RETURN VALUES

CRYPTO_memcmp() returns 0 if the memory regions are equal and non-zero
otherwise.

=head1 NOTES

Unlike memcmp(2), this function cannot be used to order the two memory regions
as the return value when they differ is undefined, other than being non-zero.

=head1 COPYRIGHT

Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file LICENSE in the source distribution or at
L<https://www.openssl.org/source/license.html>.

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