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.\" ========================================================================
.\"
.IX Title "X509_CHECK_PRIVATE_KEY 3"
.TH X509_CHECK_PRIVATE_KEY 3 "2023-09-11" "1.1.1w" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.nh
.SH "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
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #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);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fBX509_check_private_key()\fR function checks the consistency of private
key \fBk\fR with the public key in \fBx\fR.
.PP
\&\fBX509_REQ_check_private_key()\fR is equivalent to \fBX509_check_private_key()\fR
except that \fBx\fR represents a certificate request of structure \fBX509_REQ\fR.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fBX509_check_private_key()\fR and \fBX509_REQ_check_private_key()\fR return 1 if
the keys match each other, and 0 if not.
.PP
If the key is invalid or an error occurred, the reason code can be
obtained using \fBERR_get_error\fR\|(3).
.SH "BUGS"
.IX Header "BUGS"
The \fBcheck_private_key\fR functions don't check if \fBk\fR itself is indeed
a private key or not. It merely compares the public materials (e.g. exponent
and modulus of an \s-1RSA\s0 key) and/or key parameters (e.g. \s-1EC\s0 params of an \s-1EC\s0 key)
of a key pair. So if you pass a public key to these functions in \fBk\fR, it will
return success.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBERR_get_error\fR\|(3)
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2017\-2018 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the OpenSSL license (the \*(L"License\*(R").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file \s-1LICENSE\s0 in the source distribution or at
<https://www.openssl.org/source/license.html>.