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
#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);X509_check_private_key() function checks the consistency of private key k with the public key in x.
X509_REQ_check_private_key() is equivalent to X509_check_private_key() except that x represents a certificate request of structure X509_REQ.
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 ERR_get_error(3).
The check_private_key functions don't check if 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 k, it will return success.
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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 https://www.openssl.org/source/license.html.