- NAME
- SYNOPSIS
- DESCRIPTION
  - Parameters
- RETURN VALUES
- NOTES
- SEE ALSO
- HISTORY
- COPYRIGHT

# 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. The params field is a pointer to a list of OSSL_PARAM structures, terminated with a OSSL_PARAM_END(3) struct. See OSSL_PARAM(3) for information about passing 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) "Common LMS parameters" in EVP_PKEY-LMS(7) "Common parameters" in EVP_PKEY-ML-DSA(7) "Common parameters" in EVP_PKEY-ML-KEM(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.

# NOTES

LMS support is disabled by default at compile-time. To enable, specify the enable-lms build configuration option.

# 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.

Support for ML-DSA> and ML-KEM was added in OpenSSL 3.5.

Support for LMS was added in OpenSSL 3.6.

# COPYRIGHT

Copyright 2020-2025 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.