X509_CHECK_PRIVATE_KEY(3)  Library Functions Manual  X509_CHECK_PRIVATE_KEY(3)

NAME
     X509_check_private_key, X509_REQ_check_private_key - compare public key
     components

SYNOPSIS
     #include <openssl/x509.h>

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

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

DESCRIPTION
     These functions are seriously misnamed.  X509_check_private_key()
     compares the public key components (e.g. exponent and modulus of an RSA
     key) and parameters (e.g. EC params of an EC key) of k with the
     corresponding properties of x.  Despite the name, it neither checks
     whether k contains private key components at all, nor, if any are
     present, whether they are consistent with the public key components.

     X509_REQ_check_private_key() is equivalent to X509_check_private_key()
     except that it compares to the public key contained in a certificate
     request.

RETURN VALUES
     These functions return 1 if the public key components and parameters
     match, or 0 if they do not or if an error occurs.  On error or mismatch,
     a reason code can be obtained using ERR_get_error(3).

SEE ALSO
     SSL_check_private_key(3), X509_new(3), X509_REQ_new(3)

HISTORY
     X509_check_private_key() first appeared in SSLeay 0.6.5 and has been
     available since OpenBSD 2.4.

     X509_REQ_check_private_key() first appeared in OpenSSL 0.9.8 and has been
     available since OpenBSD 4.5.

Linux 6.8.2-arch2-1              June 6, 2019              Linux 6.8.2-arch2-1