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EVP_PKEY_is_a(3)                    OpenSSL                   EVP_PKEY_is_a(3)



NAME
       EVP_PKEY_is_a, EVP_PKEY_can_sign, EVP_PKEY_type_names_do_all,
       EVP_PKEY_get0_type_name, EVP_PKEY_get0_description,
       EVP_PKEY_get0_provider - key type and capabilities functions

LIBRARY
       libcrypto, -lcrypto

SYNOPSIS
        #include <openssl/evp.h>

        int EVP_PKEY_is_a(const EVP_PKEY *pkey, const char *name);
        int EVP_PKEY_can_sign(const EVP_PKEY *pkey);
        int EVP_PKEY_type_names_do_all(const EVP_PKEY *pkey,
                                       void (*fn)(const char *name, void *data),
                                       void *data);
        const char *EVP_PKEY_get0_type_name(const EVP_PKEY *key);
        const char *EVP_PKEY_get0_description(const EVP_PKEY *key);
        const OSSL_PROVIDER *EVP_PKEY_get0_provider(const EVP_PKEY *key);

DESCRIPTION
       EVP_PKEY_is_a() checks if the key type of pkey is name.

       EVP_PKEY_can_sign() checks if the functionality for the key type of
       pkey supports signing.  No other check is done, such as whether pkey
       contains a private key.

       EVP_PKEY_type_names_do_all() traverses all names for pkey's key type,
       and calls fn with each name and data.  For example, an RSA EVP_PKEY may
       be named both "RSA" and "rsaEncryption".  The order of the names
       depends on the provider implementation that holds the key.

       EVP_PKEY_get0_type_name() returns the first key type name that is found
       for the given pkey. Note that the pkey may have multiple synonyms
       associated with it. In this case it depends on the provider
       implementation that holds the key which one will be returned.
       Ownership of the returned string is retained by the pkey object and
       should not be freed by the caller.

       EVP_PKEY_get0_description() returns a description of the type of
       EVP_PKEY, meant for display and human consumption.  The description is
       at the discretion of the key type implementation.

       EVP_PKEY_get0_provider() returns the provider of the EVP_PKEY's
       EVP_KEYMGMT(3).

RETURN VALUES
       EVP_PKEY_is_a() returns 1 if pkey has the key type name, otherwise 0.

       EVP_PKEY_can_sign() returns 1 if the pkey key type functionality
       supports signing, otherwise 0.

       EVP_PKEY_get0_type_name() returns the name that is found or NULL on
       error.

       EVP_PKEY_get0_description() returns the description if found or NULL if
       not.

       EVP_PKEY_get0_provider() returns the provider if found or NULL if not.

       EVP_PKEY_type_names_do_all() returns 1 if the callback was called for
       all names. A return value of 0 means that the callback was not called
       for any names.

EXAMPLES
   EVP_PKEY_is_a()
       The loaded providers and what key types they support will ultimately
       determine what name is possible to use with EVP_PKEY_is_a().  We do
       know that the default provider supports RSA, DH, DSA and EC keys, so we
       can use this as an crude example:

        #include <openssl/evp.h>

        ...
            /* |pkey| is an EVP_PKEY* */
            if (EVP_PKEY_is_a(pkey, "RSA")) {
                BIGNUM *modulus = NULL;
                if (EVP_PKEY_get_bn_param(pkey, "n", &modulus))
                    /* do whatever with the modulus */
                BN_free(modulus);
            }

   EVP_PKEY_can_sign()
        #include <openssl/evp.h>

        ...
            /* |pkey| is an EVP_PKEY* */
            if (!EVP_PKEY_can_sign(pkey)) {
                fprintf(stderr, "Not a signing key!");
                exit(1);
            }
            /* Sign something... */

HISTORY
       The functions described here were added in OpenSSL 3.0.

COPYRIGHT
       Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (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>.



3.0.12                            2023-05-07                  EVP_PKEY_is_a(3)