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=head1 NAME

X509_check_private_key, X509_REQ_check_private_key - check the consistency
of a private key with the public key in an X509 certificate or certificate
request

=head1 SYNOPSIS

 #include <openssl/x509.h>

 int X509_check_private_key(X509 *x, EVP_PKEY *k);

 int X509_REQ_check_private_key(X509_REQ *x, EVP_PKEY *k);

=head1 DESCRIPTION

X509_check_private_key() function checks the consistency of private
key B<k> with the public key in B<x>.

X509_REQ_check_private_key() is equivalent to X509_check_private_key()
except that B<x> represents a certificate request of structure B<X509_REQ>.

=head1 RETURN VALUES

X509_check_private_key() and X509_REQ_check_private_key() return 1 if
the keys match each other, and 0 if not.

If the key is invalid or an error occurred, the reason code can be
obtained using L<ERR_get_error(3)>.

=head1 BUGS

The B<check_private_key> functions don't check if B<k> itself is indeed
a private key or not. It merely compares the public materials (e.g. exponent
and modulus of an RSA key) and/or key parameters (e.g. EC params of an EC key)
of a key pair. So if you pass a public key to these functions in B<k>, it will
return success.

=head1 SEE ALSO

L<ERR_get_error(3)>

=head1 COPYRIGHT

Copyright 2017-2018 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (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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