dtls_ccm.h

/*******************************************************************************
 *
 * Copyright (c) 2011, 2012, 2013, 2014, 2015 Olaf Bergmann (TZI) and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * and Eclipse Distribution License v. 1.0 which accompanies this distribution.
 *
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at 
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *    Olaf Bergmann  - initial API and implementation
 *    Hauke Mehrtens - memory optimization, ECC integration
 *
 *******************************************************************************/

#ifndef _DTLS_CCM_H_
#define _DTLS_CCM_H_

#include "aes/rijndael.h"

/* implementation of Counter Mode CBC-MAC, RFC 3610 */

#define DTLS_CCM_BLOCKSIZE  16	/**< size of hmac blocks */
#define DTLS_CCM_MAX        16	/**< max number of bytes in digest */
#define DTLS_CCM_NONCE_SIZE 12	/**< size of nonce */

/** 
 * Authenticates and encrypts a message using AES in CCM mode. Please
 * see also RFC 3610 for the meaning of \p M, \p L, \p lm and \p la.
 * 
 * \param ctx The initialized rijndael_ctx object to be used for AES operations.
 * \param M   The number of authentication octets.
 * \param L   The number of bytes used to encode the message length.
 * \param N   The nonce value to use. You must provide \c DTLS_CCM_BLOCKSIZE 
 *            nonce octets, although only the first \c 16 - \p L - 1 are used.
 * \param msg The message to encrypt. The first \p la octets are additional
 *            authentication data that will be cleartext. Note that the 
 *            encryption operation modifies the contents of \p msg and adds 
 *            \p M bytes MAC. Therefore, the buffer must be at least
 *            \p lm + \p M bytes large.
 * \param lm  The actual length of \p msg.
 * \param aad A pointer to the additional authentication data (can be \c NULL if
 *            \p la is zero).
 * \param la  The number of additional authentication octets (may be zero).
 * \return FIXME
 */
long int
dtls_ccm_encrypt_message(rijndael_ctx *ctx, size_t M, size_t L, 
			 unsigned char nonce[DTLS_CCM_BLOCKSIZE], 
			 unsigned char *msg, size_t lm, 
			 const unsigned char *aad, size_t la);

long int
dtls_ccm_decrypt_message(rijndael_ctx *ctx, size_t M, size_t L, 
			 unsigned char nonce[DTLS_CCM_BLOCKSIZE], 
			 unsigned char *msg, size_t lm, 
			 const unsigned char *aad, size_t la);

#endif /* _DTLS_CCM_H_ */