/*
 * Copyright (C) 2023 - 2026, Stephan Mueller <smueller@chronox.de>
 *
 * License: see LICENSE file in root directory
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
 * WHICH ARE HEREBY DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 */

#ifndef LC_X25519_H
#define LC_X25519_H

#include "lc_rng.h"
#include "lc_status.h"

#ifdef __cplusplus
extern "C" {
#endif

#define LC_X25519_SECRETKEYBYTES (32U)
#define LC_X25519_PUBLICKEYBYTES (32U)
#define LC_X25519_SSBYTES (32U)

struct lc_x25519_sk {
	uint8_t sk[LC_X25519_SECRETKEYBYTES];
};

struct lc_x25519_pk {
	uint8_t pk[LC_X25519_PUBLICKEYBYTES];
};

struct lc_x25519_ss {
	uint8_t ss[LC_X25519_SSBYTES];
};

/*
 * These interfaces are used for testing or for rustTLS - they are NOT
 * intended as general-purpose API as they are not PQC-safe
 */
int lc_x25519_keypair(struct lc_x25519_pk *pk, struct lc_x25519_sk *sk,
		      struct lc_rng_ctx *rng_ctx);
int lc_x25519_pk_from_sk(struct lc_x25519_pk *pk,
			 const struct lc_x25519_sk *sk);
int lc_x25519_ss(struct lc_x25519_ss *ss, const struct lc_x25519_pk *pk,
		 const struct lc_x25519_sk *sk);
int lc_x25519_sk_ptr(uint8_t **x25519_key, size_t *x25519_key_len,
		     struct lc_x25519_sk *sk);
int lc_x25519_pk_ptr(uint8_t **x25519_key, size_t *x25519_key_len,
		     struct lc_x25519_pk *pk);
int lc_x25519_ss_ptr(uint8_t **x25519_ss, size_t *x25519_ss_len,
		     struct lc_x25519_ss *ss);
int lc_x25519_sk_load(struct lc_x25519_sk *sk, const uint8_t *src_key,
		      size_t src_key_len);
int lc_x25519_pk_load(struct lc_x25519_pk *pk, const uint8_t *src_key,
		      size_t src_key_len);
int lc_x25519_ss_load(struct lc_x25519_ss *ss, const uint8_t *src_sig,
		      size_t src_sig_len);

enum lc_x25519_alg_operation {
	/** Unknown operation */
	lc_alg_operation_x25519_unknown,
	/** ED25519: key generation operation */
	lc_alg_operation_x25519_keygen,
	/** ED25519: shared secret generation operation */
	lc_alg_operation_x25519_ss,
};

/**
 * @brief Obtain algorithm status
 *
 * @param [in] operation X25519 algorithm type
 *
 * @return algorithm status
 */
enum lc_alg_status_val
lc_x25519_alg_status(const enum lc_x25519_alg_operation operation);

#ifdef __cplusplus
}
#endif

#endif /* LC_X25519_H */