include/polarssl/ccm.h

/**
 * \file ccm.h
 *
 * \brief Counter with CBC-MAC (CCM) for 128-bit block ciphers
 *
 *  Copyright (C) 2014, 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_CCM_H
#define POLARSSL_CCM_H

#include "cipher.h"

#define POLARSSL_ERR_CCM_BAD_INPUT      -0x000D /**< Bad input parameters to function. */
#define POLARSSL_ERR_CCM_AUTH_FAILED    -0x000F /**< Authenticated decryption failed. */

#ifdef __cplusplus
extern "C" {
#endif

/**
 * \brief          CCM context structure
 */
typedef struct {
    cipher_context_t cipher_ctx;    /*!< cipher context used */
}
ccm_context;

/**
 * \brief           CCM initialization (encryption and decryption)
 *
 * \param ctx       CCM context to be initialized
 * \param cipher    cipher to use (a 128-bit block cipher)
 * \param key       encryption key
 * \param keysize   key size in bits (must be acceptable by the cipher)
 *
 * \return          0 if successful, or a cipher specific error code
 */
int ccm_init( ccm_context *ctx, cipher_id_t cipher,
              const unsigned char *key, unsigned int keysize );

/**
 * \brief           Free a CCM context and underlying cipher sub-context
 *
 * \param ctx       CCM context to free
 */
void ccm_free( ccm_context *ctx );

/**
 * \brief           CCM buffer encryption
 *
 * \todo            Document if input/output buffers can be the same
 *
 * \param ctx       CCM context
 * \param length    length of the input data in bytes
 * \param iv        nonce (initialization vector)
 * \param iv_len    length of IV in bytes
 *                  must be 2, 3, 4, 5, 6, 7 or 8
 * \param add       additional data
 * \param add_len   length of additional data in bytes
 *                  must be less than 2^16 - 2^8
 * \param input     buffer holding the input data
 * \param output    buffer for holding the output data
 *                  must be at least 'length' bytes wide
 * \param tag       buffer for holding the tag
 * \param tag_len   length of the tag to generate in bytes
 *                  must be 4, 6, 8, 10, 14 or 16
 *
 * \note            The tag is written to a separate buffer. To get the tag
 *                  concatenated with the output as in the CCM spec, use
 *                  tag = output + length and make sure the output buffer is
 *                  at least length + tag_len wide.
 *
 * \return          0 if successful
 */
int ccm_encrypt_and_tag( ccm_context *ctx, size_t length,
                         const unsigned char *iv, size_t iv_len,
                         const unsigned char *add, size_t add_len,
                         const unsigned char *input, unsigned char *output,
                         unsigned char *tag, size_t tag_len );

/**
 * \brief           CCM buffer authenticated decryption
 *
 * \todo            Document if input/output buffers can be the same
 *
 * \param ctx       CCM context
 * \param length    length of the input data
 * \param iv        initialization vector
 * \param iv_len    length of IV
 * \param add       additional data
 * \param add_len   length of additional data
 * \param input     buffer holding the input data
 * \param output    buffer for holding the output data
 * \param tag       buffer holding the tag
 * \param tag_len   length of the tag
 *
 * \return         0 if successful and authenticated,
 *                 POLARSSL_ERR_CCM_AUTH_FAILED if tag does not match
 */
int ccm_auth_decrypt( ccm_context *ctx, size_t length,
                      const unsigned char *iv, size_t iv_len,
                      const unsigned char *add, size_t add_len,
                      const unsigned char *input, unsigned char *output,
                      const unsigned char *tag, size_t tag_len );

#if defined(POLARSSL_SELF_TEST) && defined(POLARSSL_AES_C)
/**
 * \brief          Checkup routine
 *
 * \return         0 if successful, or 1 if the test failed
 */
int ccm_self_test( int verbose );
#endif /* POLARSSL_SELF_TEST && POLARSSL_AES_C */

#ifdef __cplusplus
}
#endif

#endif /* POLARSSL_CGM_H */