/**
 * \file aes.h
 *
 * \brief AES block cipher
 *
 *  Copyright (C) 2006-2010, Brainspark B.V.
 *
 *  This file is part of PolarSSL (http://www.polarssl.org)
 *  Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
 *
 *  All rights reserved.
 *
 *  This program 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.
 *
 *  This program 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 02110-1301 USA.
 */
#ifndef POLARSSL_AES_H
#define POLARSSL_AES_H

#include <string.h>

#define AES_ENCRYPT     1
#define AES_DECRYPT     0

#define POLARSSL_ERR_AES_INVALID_KEY_LENGTH                -0x0020  /**< Invalid key length. */
#define POLARSSL_ERR_AES_INVALID_INPUT_LENGTH              -0x0022  /**< Invalid data input length. */

/**
 * \brief          AES context structure
 */
typedef struct
{
    int nr;                     /*!<  number of rounds  */
    unsigned long *rk;          /*!<  AES round keys    */
    unsigned long buf[68];      /*!<  unaligned data    */
}
aes_context;

#ifdef __cplusplus
extern "C" {
#endif

/**
 * \brief          AES key schedule (encryption)
 *
 * \param ctx      AES context to be initialized
 * \param key      encryption key
 * \param keysize  must be 128, 192 or 256
 *
 * \return         0 if successful, or POLARSSL_ERR_AES_INVALID_KEY_LENGTH
 */
int aes_setkey_enc( aes_context *ctx, const unsigned char *key, unsigned int keysize );

/**
 * \brief          AES key schedule (decryption)
 *
 * \param ctx      AES context to be initialized
 * \param key      decryption key
 * \param keysize  must be 128, 192 or 256
 *
 * \return         0 if successful, or POLARSSL_ERR_AES_INVALID_KEY_LENGTH
 */
int aes_setkey_dec( aes_context *ctx, const unsigned char *key, unsigned int keysize );

/**
 * \brief          AES-ECB block encryption/decryption
 *
 * \param ctx      AES context
 * \param mode     AES_ENCRYPT or AES_DECRYPT
 * \param input    16-byte input block
 * \param output   16-byte output block
 *
 * \return         0 if successful
 */
int aes_crypt_ecb( aes_context *ctx,
                    int mode,
                    const unsigned char input[16],
                    unsigned char output[16] );

/**
 * \brief          AES-CBC buffer encryption/decryption
 *                 Length should be a multiple of the block
 *                 size (16 bytes)
 *
 * \param ctx      AES context
 * \param mode     AES_ENCRYPT or AES_DECRYPT
 * \param length   length of the input data
 * \param iv       initialization vector (updated after use)
 * \param input    buffer holding the input data
 * \param output   buffer holding the output data
 *
 * \return         0 if successful, or POLARSSL_ERR_AES_INVALID_INPUT_LENGTH
 */
int aes_crypt_cbc( aes_context *ctx,
                    int mode,
                    size_t length,
                    unsigned char iv[16],
                    const unsigned char *input,
                    unsigned char *output );

/*
 * \brief               AES-CTR buffer encryption/decryption
 *
 * Warning: You have to keep the maximum use of your counter in mind!
 *
 * Note: Due to the nature of CTR you should use the same key schedule for
 * both encryption and decryption. So a context initialized with
 * aes_setkey_enc() for both AES_ENCRYPT and AES_DECRYPT.
 *
 * \param length        The length of the data
 * \param nc_off        The offset in the current stream_block (for resuming
 *                      within current cipher stream). The offset pointer to
 *                      should be 0 at the start of a stream.
 * \param nonce_counter The 128-bit nonce and counter.
 * \param stream_block  The saved stream-block for resuming. Is overwritten
 *                      by the function.
 * \param input         The input data stream
 * \param output        The output data stream
 *
 * \return         0 if successful
 */
int aes_crypt_ctr( aes_context *ctx,
                       size_t length,
                       size_t *nc_off,
                       unsigned char nonce_counter[16],
                       unsigned char stream_block[16],
                       const unsigned char *input,
                       unsigned char *output );

#ifdef __cplusplus
}
#endif

#endif /* aes.h */