155 lines
4.5 KiB
C
155 lines
4.5 KiB
C
/*
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* Copyright (c) 2013, Hasso-Plattner-Institut.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This file is part of the Contiki operating system.
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*
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*/
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/**
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* \file
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* AES_128-based CCM* implementation.
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* \author
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* Original: Konrad Krentz <konrad.krentz@gmail.com>
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* Generified version: Justin King-Lacroix <justin.kinglacroix@gmail.com>
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*/
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#include "ccm-star.h"
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#include "lib/aes-128.h"
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#include <string.h>
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/* see RFC 3610 */
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#define CCM_STAR_AUTH_FLAGS(Adata, M) ((Adata ? (1u << 6) : 0) | (((M - 2u) >> 1) << 3) | 1u)
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#define CCM_STAR_ENCRYPTION_FLAGS 1
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/*---------------------------------------------------------------------------*/
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static void
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set_iv(uint8_t *iv,
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uint8_t flags,
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const uint8_t *nonce,
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uint8_t counter)
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{
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iv[0] = flags;
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memcpy(iv + 1, nonce, CCM_STAR_NONCE_LENGTH);
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iv[14] = 0;
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iv[15] = counter;
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}
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/*---------------------------------------------------------------------------*/
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/* XORs the block m[pos] ... m[pos + 15] with K_{counter} */
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static void
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ctr_step(const uint8_t *nonce,
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uint8_t pos,
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uint8_t *m_and_result,
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uint8_t m_len,
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uint8_t counter)
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{
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uint8_t a[AES_128_BLOCK_SIZE];
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uint8_t i;
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set_iv(a, CCM_STAR_ENCRYPTION_FLAGS, nonce, counter);
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AES_128.encrypt(a);
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for(i = 0; (pos + i < m_len) && (i < AES_128_BLOCK_SIZE); i++) {
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m_and_result[pos + i] ^= a[i];
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}
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}
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/*---------------------------------------------------------------------------*/
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static void
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mic(const uint8_t *nonce,
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const uint8_t *m, uint8_t m_len,
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const uint8_t *a, uint8_t a_len,
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uint8_t *result,
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uint8_t mic_len)
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{
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uint8_t x[AES_128_BLOCK_SIZE];
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uint8_t pos;
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uint8_t i;
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set_iv(x, CCM_STAR_AUTH_FLAGS(a_len, mic_len), nonce, m_len);
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AES_128.encrypt(x);
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if(a_len) {
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x[1] = x[1] ^ a_len;
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for(i = 2; (i - 2 < a_len) && (i < AES_128_BLOCK_SIZE); i++) {
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x[i] ^= a[i - 2];
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}
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AES_128.encrypt(x);
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pos = 14;
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while(pos < a_len) {
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for(i = 0; (pos + i < a_len) && (i < AES_128_BLOCK_SIZE); i++) {
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x[i] ^= a[pos + i];
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}
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pos += AES_128_BLOCK_SIZE;
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AES_128.encrypt(x);
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}
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}
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if(m_len) {
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pos = 0;
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while(pos < m_len) {
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for(i = 0; (pos + i < m_len) && (i < AES_128_BLOCK_SIZE); i++) {
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x[i] ^= m[pos + i];
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}
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pos += AES_128_BLOCK_SIZE;
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AES_128.encrypt(x);
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}
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}
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ctr_step(nonce, 0, x, AES_128_BLOCK_SIZE, 0);
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memcpy(result, x, mic_len);
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}
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/*---------------------------------------------------------------------------*/
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static void
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ctr(const uint8_t *nonce, uint8_t *m, uint8_t m_len)
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{
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uint8_t pos;
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uint8_t counter;
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pos = 0;
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counter = 1;
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while(pos < m_len) {
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ctr_step(nonce, pos, m, m_len, counter++);
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pos += AES_128_BLOCK_SIZE;
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}
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}
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/*---------------------------------------------------------------------------*/
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static void
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set_key(const uint8_t *key)
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{
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AES_128.set_key(key);
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}
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/*---------------------------------------------------------------------------*/
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const struct ccm_star_driver ccm_star_driver = {
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mic,
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ctr,
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set_key
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};
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/*---------------------------------------------------------------------------*/
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