NAME

       EVP_PKEY_CTX_set_params, EVP_PKEY_CTX_settable_params, EVP_PKEY_CTX_get_params,
       EVP_PKEY_CTX_gettable_params - provider parameter passing operations

SYNOPSIS

        #include <openssl/evp.h>

        int EVP_PKEY_CTX_set_params(EVP_PKEY_CTX *ctx, const OSSL_PARAM *params);
        const OSSL_PARAM *EVP_PKEY_CTX_settable_params(const EVP_PKEY_CTX *ctx);
        int EVP_PKEY_CTX_get_params(EVP_PKEY_CTX *ctx, OSSL_PARAM *params);
        const OSSL_PARAM *EVP_PKEY_CTX_gettable_params(const EVP_PKEY_CTX *ctx);

DESCRIPTION

       The EVP_PKEY_CTX_get_params() and EVP_PKEY_CTX_set_params() functions allow transfer of
       arbitrary key parameters to and from providers.  Not all parameters may be supported by
       all providers.  See OSSL_PROVIDER(3) for more information on providers.  See OSSL_PARAM(3)
       for more information on parameters.  These functions must only be called after the
       EVP_PKEY_CTX has been initialised for use in an operation.  These methods replace the
       EVP_PKEY_CTX_ctrl() mechanism. (EVP_PKEY_CTX_ctrl now calls these methods internally to
       interact with providers).

       EVP_PKEY_CTX_gettable_params() and EVP_PKEY_CTX_settable_params() get a constant
       OSSL_PARAM(3) array that describes the gettable and settable parameters for the current
       algorithm implementation, i.e. parameters that can be used with EVP_PKEY_CTX_get_params()
       and EVP_PKEY_CTX_set_params() respectively.  These functions must only be called after the
       EVP_PKEY_CTX has been initialised for use in an operation.

   Parameters
       Examples of EVP_PKEY parameters include the following:

       "Common parameters" in provider-keymgmt(7) "Key Exchange parameters" in
       provider-keyexch(7) "Signature parameters" in provider-signature(7)

       "Common RSA parameters" in EVP_PKEY-RSA(7) "RSA key generation parameters" in
       EVP_PKEY-RSA(7) "FFC parameters" in EVP_PKEY-FFC(7) "FFC key generation parameters" in
       EVP_PKEY-FFC(7) "DSA parameters" in EVP_PKEY-DSA(7) "DSA key generation parameters" in
       EVP_PKEY-DSA(7) "DH parameters" in EVP_PKEY-DH(7) "DH key generation parameters" in
       EVP_PKEY-DH(7) "Common EC parameters" in EVP_PKEY-EC(7) "Common X25519, X448, ED25519 and
       ED448 parameters" in EVP_PKEY-X25519(7)

RETURN VALUES

       EVP_PKEY_CTX_set_params() returns 1 for success or 0 otherwise.
       EVP_PKEY_CTX_settable_params() returns an OSSL_PARAM array on success or NULL on error.
       It may also return NULL if there are no settable parameters available.

       All other functions and macros described on this page return a positive value for success
       and 0 or a negative value for failure. In particular a return value of -2 indicates the
       operation is not supported by the public key algorithm.

SEE ALSO

       EVP_PKEY_CTX_new(3), EVP_PKEY_encrypt(3), EVP_PKEY_decrypt(3), EVP_PKEY_sign(3),
       EVP_PKEY_verify(3), EVP_PKEY_verify_recover(3), EVP_PKEY_derive(3), EVP_PKEY_keygen(3)

HISTORY

       All functions 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>.