/*
 *  PSA FFDH layer on top of Mbed TLS crypto
 */
/*
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

#ifndef PSA_CRYPTO_FFDH_H
#define PSA_CRYPTO_FFDH_H

#include <psa/crypto.h>
#include <mbedtls/dhm.h>

/** Perform a key agreement and return the FFDH shared secret.
 *
 * \param[in]  attributes           The attributes of the key to use for the
 *                                  operation.
 * \param[in]  peer_key             The buffer containing the key context
 *                                  of the peer's public key.
 * \param[in]  peer_key_length      Size of the \p peer_key buffer in
 *                                  bytes.
 * \param[in]  key_buffer           The buffer containing the private key
 *                                  context.
 * \param[in]  key_buffer_size      Size of the \p key_buffer buffer in
 *                                  bytes.
 * \param[out] shared_secret        The buffer to which the shared secret
 *                                  is to be written.
 * \param[in]  shared_secret_size   Size of the \p shared_secret buffer in
 *                                  bytes.
 * \param[out] shared_secret_length On success, the number of bytes that make
 *                                  up the returned shared secret.
 * \retval #PSA_SUCCESS
 *         Success. Shared secret successfully calculated.
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \p key_buffer_size, \p peer_key_length, \p shared_secret_size
 *         do not match
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_CORRUPTION_DETECTED
 */
psa_status_t mbedtls_psa_key_agreement_ffdh(
    const psa_key_attributes_t *attributes,
    const uint8_t *peer_key,
    size_t peer_key_length,
    const uint8_t *key_buffer,
    size_t key_buffer_size,
    uint8_t *shared_secret,
    size_t shared_secret_size,
    size_t *shared_secret_length);

/** Export a public key or the public part of a DH key pair in binary format.
 *
 * \param[in]  attributes       The attributes for the key to export.
 * \param[in]  key_buffer       Material or context of the key to export.
 * \param[in]  key_buffer_size  Size of the \p key_buffer buffer in bytes.
 * \param[out] data             Buffer where the key data is to be written.
 * \param[in]  data_size        Size of the \p data buffer in bytes.
 * \param[out] data_length      On success, the number of bytes written in
 *                              \p data
 *
 * \retval #PSA_SUCCESS  The public key was exported successfully.
 * \retval #PSA_ERROR_BUFFER_TOO_SMALL
 *         The size of \p key_buffer is too small.
 * \retval #PSA_ERROR_NOT_PERMITTED
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_CORRUPTION_DETECTED
 */
psa_status_t mbedtls_psa_export_ffdh_public_key(
    const psa_key_attributes_t *attributes,
    const uint8_t *key_buffer,
    size_t key_buffer_size,
    uint8_t *data,
    size_t data_size,
    size_t *data_length);

/**
 * \brief Generate DH key.
 *
 * \note The signature of the function is that of a PSA driver generate_key
 *       entry point.
 *
 * \param[in]  attributes         The attributes for the key to generate.
 * \param[out] key_buffer         Buffer where the key data is to be written.
 * \param[in]  key_buffer_size    Size of \p key_buffer in bytes.
 * \param[out] key_buffer_length  On success, the number of bytes written in
 *                                \p key_buffer.
 *
 * \retval #PSA_SUCCESS
 *         The key was generated successfully.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         Key size in bits is invalid.
 * \retval #PSA_ERROR_BUFFER_TOO_SMALL
 *         The size of \p key_buffer is too small.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_CORRUPTION_DETECTED
 */
psa_status_t mbedtls_psa_ffdh_generate_key(
    const psa_key_attributes_t *attributes,
    uint8_t *key_buffer,
    size_t key_buffer_size,
    size_t *key_buffer_length);

#endif /* PSA_CRYPTO_FFDH_H */