/* curve25519.h
 *
 * Copyright (C) 2006-2017 wolfSSL Inc.
 *
 * This file is part of wolfSSL.
 *
 * wolfSSL is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * wolfSSL is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
 */


#ifndef WOLF_CRYPT_CURVE25519_H
# define WOLF_CRYPT_CURVE25519_H

# include <wolfssl/wolfcrypt/types.h>

# ifdef HAVE_CURVE25519

#  include <wolfssl/wolfcrypt/fe_operations.h>
#  include <wolfssl/wolfcrypt/random.h>

#  ifdef WOLFSSL_ASYNC_CRYPT
#   include <wolfssl/wolfcrypt/async.h>
#  endif

#  ifdef __cplusplus
extern "C" {
#  endif

#  define CURVE25519_KEYSIZE 32

/* curve25519 set type */
typedef struct {
    int          size; /* The size of the curve in octets */
    const char * name; /* name of this curve */
} curve25519_set_type;


/* ECC point, the internal structure is Little endian
 * the mathematical functions used the endianess */
typedef struct {
    byte point[CURVE25519_KEYSIZE];
    #  ifdef FREESCALE_LTC_ECC
    byte pointY[CURVE25519_KEYSIZE];
    #  endif
} ECPoint;

/* A CURVE25519 Key */
typedef struct curve25519_key {
    int                         idx; /* Index into the ecc_sets[] for the parameters of
                                      * this curve if -1, this key is using user supplied
                                      * curve in dp */
    const curve25519_set_type * dp;  /* domain parameters, either points to
                                      * curves (idx >= 0) or user supplied */
    ECPoint                     p;   /* public key  */
    ECPoint                     k;   /* private key */

    #  ifdef WOLFSSL_ASYNC_CRYPT
    WC_ASYNC_DEV                asyncDev;
    #  endif
} curve25519_key;

enum {
    EC25519_LITTLE_ENDIAN = 0,
    EC25519_BIG_ENDIAN    = 1
};

WOLFSSL_API
int
wc_curve25519_make_key(WC_RNG * rng, int keysize, curve25519_key * key);

WOLFSSL_API
int
wc_curve25519_shared_secret(curve25519_key * private_key,
  curve25519_key * public_key,
  byte * out, word32 * outlen);

WOLFSSL_API
int
wc_curve25519_shared_secret_ex(curve25519_key * private_key,
  curve25519_key * public_key,
  byte * out, word32 * outlen, int endian);

WOLFSSL_API
int
wc_curve25519_init(curve25519_key * key);

WOLFSSL_API
void
wc_curve25519_free(curve25519_key * key);


/* raw key helpers */
WOLFSSL_API
int
wc_curve25519_import_private(const byte * priv, word32 privSz,
  curve25519_key * key);
WOLFSSL_API
int
wc_curve25519_import_private_ex(const byte * priv, word32 privSz,
  curve25519_key * key, int endian);

WOLFSSL_API
int
wc_curve25519_import_private_raw(const byte * priv, word32 privSz,
  const byte * pub, word32 pubSz, curve25519_key * key);
WOLFSSL_API
int
wc_curve25519_import_private_raw_ex(const byte * priv, word32 privSz,
  const byte * pub, word32 pubSz,
  curve25519_key * key, int endian);
WOLFSSL_API
int
wc_curve25519_export_private_raw(curve25519_key * key, byte * out,
  word32 * outLen);
WOLFSSL_API
int
wc_curve25519_export_private_raw_ex(curve25519_key * key, byte * out,
  word32 * outLen, int endian);

WOLFSSL_API
int
wc_curve25519_import_public(const byte * in, word32 inLen,
  curve25519_key * key);
WOLFSSL_API
int
wc_curve25519_import_public_ex(const byte * in, word32 inLen,
  curve25519_key * key, int endian);

WOLFSSL_API
int
wc_curve25519_export_public(curve25519_key * key, byte * out, word32 * outLen);
WOLFSSL_API
int
wc_curve25519_export_public_ex(curve25519_key * key, byte * out,
  word32 * outLen, int endian);

WOLFSSL_API
int
wc_curve25519_export_key_raw(curve25519_key * key,
  byte * priv, word32 * privSz,
  byte * pub, word32 * pubSz);
WOLFSSL_API
int
wc_curve25519_export_key_raw_ex(curve25519_key * key,
  byte * priv, word32 * privSz,
  byte * pub, word32 * pubSz,
  int endian);
/* size helper */
WOLFSSL_API
int
wc_curve25519_size(curve25519_key * key);

#  ifdef __cplusplus
} /* extern "C" */
#  endif

# endif /* HAVE_CURVE25519 */
#endif  /* WOLF_CRYPT_CURVE25519_H */
