NAME

       EVP_PKEY_copy_parameters, EVP_PKEY_missing_parameters, EVP_PKEY_cmp_parameters,
       EVP_PKEY_cmp - public key parameter and comparison functions

SYNOPSIS

        #include <openssl/evp.h>

        int EVP_PKEY_missing_parameters(const EVP_PKEY *pkey);
        int EVP_PKEY_copy_parameters(EVP_PKEY *to, const EVP_PKEY *from);

        int EVP_PKEY_cmp_parameters(const EVP_PKEY *a, const EVP_PKEY *b);
        int EVP_PKEY_cmp(const EVP_PKEY *a, const EVP_PKEY *b);

DESCRIPTION

       The function EVP_PKEY_missing_parameters() returns 1 if the public key parameters of pkey
       are missing and 0 if they are present or the algorithm doesn't use parameters.

       The function EVP_PKEY_copy_parameters() copies the parameters from key from to key to. An
       error is returned if the parameters are missing in from or present in both from and to and
       mismatch. If the parameters in from and to are both present and match this function has no
       effect.

       The function EVP_PKEY_cmp_parameters() compares the parameters of keys a and b.

       The function EVP_PKEY_cmp() compares the public key components and parameters (if present)
       of keys a and b.

NOTES

       The main purpose of the functions EVP_PKEY_missing_parameters() and
       EVP_PKEY_copy_parameters() is to handle public keys in certificates where the parameters
       are sometimes omitted from a public key if they are inherited from the CA that signed it.

       Since OpenSSL private keys contain public key components too the function EVP_PKEY_cmp()
       can also be used to determine if a private key matches a public key.

RETURN VALUES

       The function EVP_PKEY_missing_parameters() returns 1 if the public key parameters of pkey
       are missing and 0 if they are present or the algorithm doesn't use parameters.

       These functions EVP_PKEY_copy_parameters() returns 1 for success and 0 for failure.

       The function EVP_PKEY_cmp_parameters() and EVP_PKEY_cmp() return 1 if the keys match, 0 if
       they don't match, -1 if the key types are different and -2 if the operation is not
       supported.

SEE ALSO

       EVP_PKEY_CTX_new(3), EVP_PKEY_keygen(3)

COPYRIGHT

       Copyright 2006-2016 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 <https://www.openssl.org/source/license.html>.