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/* chacha-poly1305.h
 *
 * AEAD mechanism based on chacha and poly1305.
 * See draft-agl-tls-chacha20poly1305-04.
 */

/* nettle, low-level cryptographics library
 *
 * Copyright (C) 2014 Niels Möller
 *
 * The nettle library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or (at your
 * option) any later version.
 *
 * The nettle library 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 Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with the nettle library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02111-1301, USA.
 */

#ifndef NETTLE_CHACHA_POLY1305_H_INCLUDED
#define NETTLE_CHACHA_POLY1305_H_INCLUDED

#include "chacha.h"
#include "poly1305.h"

#ifdef __cplusplus
extern "C" {
#endif

/* Name mangling */
#define chacha_poly1305_set_key nettle_chacha_poly1305_set_key
#define chacha_poly1305_set_nonce nettle_chacha_poly1305_set_nonce
#define chacha_poly1305_update nettle_chacha_poly1305_update
#define chacha_poly1305_decrypt nettle_chacha_poly1305_decrypt
#define chacha_poly1305_encrypt nettle_chacha_poly1305_encrypt
#define chacha_poly1305_digest nettle_chacha_poly1305_digest

#define CHACHA_POLY1305_BLOCK_SIZE 64
/* FIXME: Any need for 128-bit variant? */
#define CHACHA_POLY1305_KEY_SIZE 32
#define CHACHA_POLY1305_NONCE_SIZE CHACHA_NONCE_SIZE
#define CHACHA_POLY1305_DIGEST_SIZE 16

struct chacha_poly1305_ctx
{
  struct chacha_ctx chacha;
  struct poly1305_ctx poly1305;
  union nettle_block16 s;
  uint64_t auth_size;
  uint64_t data_size;
  /* poly1305 block */
  uint8_t block[POLY1305_BLOCK_SIZE];
  unsigned index;
};

void
chacha_poly1305_set_key (struct chacha_poly1305_ctx *ctx,
			 const uint8_t *key);
void
chacha_poly1305_set_nonce (struct chacha_poly1305_ctx *ctx,
			   const uint8_t *nonce);

void
chacha_poly1305_update (struct chacha_poly1305_ctx *ctx,
			size_t length, const uint8_t *data);

void
chacha_poly1305_encrypt (struct chacha_poly1305_ctx *ctx,
			 size_t length, uint8_t *dst, const uint8_t *src);
			 
void
chacha_poly1305_decrypt (struct chacha_poly1305_ctx *ctx,
			 size_t length, uint8_t *dst, const uint8_t *src);
			 
void
chacha_poly1305_digest (struct chacha_poly1305_ctx *ctx,
			size_t length, uint8_t *digest);

#ifdef __cplusplus
}
#endif

#endif /* NETTLE_CHACHA_POLY1305_H_INCLUDED */