Backport X509_check_private_key.pod

=pod

=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 VALUE

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 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>.

=cut