/* chacha20_poly1305.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
 */


/* This implementation of the ChaCha20-Poly1305 AEAD is based on "ChaCha20
 * and Poly1305 for IETF protocols" (draft-irtf-cfrg-chacha20-poly1305-10):
 * https://tools.ietf.org/html/draft-irtf-cfrg-chacha20-poly1305-10
 */

#ifndef WOLF_CRYPT_CHACHA20_POLY1305_H
# define WOLF_CRYPT_CHACHA20_POLY1305_H

# include <wolfssl/wolfcrypt/types.h>

# if defined(HAVE_CHACHA) && defined(HAVE_POLY1305)

#  ifdef __cplusplus
extern "C" {
#  endif

#  define CHACHA20_POLY1305_AEAD_KEYSIZE      32
#  define CHACHA20_POLY1305_AEAD_IV_SIZE      12
#  define CHACHA20_POLY1305_AEAD_AUTHTAG_SIZE 16

enum {
    CHACHA20_POLY_1305_ENC_TYPE = 8 /* cipher unique type */
};

/*
 * The IV for this implementation is 96 bits to give the most flexibility.
 *
 * Some protocols may have unique per-invocation inputs that are not
 * 96-bit in length. For example, IPsec may specify a 64-bit nonce. In
 * such a case, it is up to the protocol document to define how to
 * transform the protocol nonce into a 96-bit nonce, for example by
 * concatenating a constant value.
 */

WOLFSSL_API
int
wc_ChaCha20Poly1305_Encrypt(
    const byte inKey[CHACHA20_POLY1305_AEAD_KEYSIZE],
    const byte inIV[CHACHA20_POLY1305_AEAD_IV_SIZE],
    const byte * inAAD, const word32 inAADLen,
    const byte * inPlaintext, const word32 inPlaintextLen,
    byte * outCiphertext,
    byte outAuthTag[CHACHA20_POLY1305_AEAD_AUTHTAG_SIZE]);

WOLFSSL_API
int
wc_ChaCha20Poly1305_Decrypt(
    const byte inKey[CHACHA20_POLY1305_AEAD_KEYSIZE],
    const byte inIV[CHACHA20_POLY1305_AEAD_IV_SIZE],
    const byte * inAAD, const word32 inAADLen,
    const byte * inCiphertext, const word32 inCiphertextLen,
    const byte inAuthTag[CHACHA20_POLY1305_AEAD_AUTHTAG_SIZE],
    byte * outPlaintext);

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

# endif /* HAVE_CHACHA && HAVE_POLY1305 */
#endif  /* WOLF_CRYPT_CHACHA20_POLY1305_H */
