162 lines
4.8 KiB
C
162 lines
4.8 KiB
C
/* bcal-omac.c */
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/*
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This file is part of the AVR-Crypto-Lib.
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Copyright (C) 2010 Daniel Otte (daniel.otte@rub.de)
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdint.h>
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#include <string.h>
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#include "bcal-basic.h"
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#include "bcal-cmac.h"
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#include "memxor.h"
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static uint8_t left_shift_be_block(void *block, uint8_t blocksize_B)
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{
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uint8_t c1 = 0, c2;
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do {
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--blocksize_B;
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c2 = (((uint8_t*) block)[blocksize_B]) >> 7;
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(((uint8_t*) block)[blocksize_B]) <<= 1;
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(((uint8_t*) block)[blocksize_B]) |= c1;
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c1 = c2;
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} while (blocksize_B);
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return c1;
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}
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static const uint8_t const_128 = 0x87;
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static const uint8_t const_64 = 0x1b;
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uint8_t bcal_cmac_init(const bcdesc_t *desc, const void *key,
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uint16_t keysize_b, bcal_cmac_ctx_t *ctx)
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{
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uint8_t r;
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ctx->desc = (bcdesc_t*) desc;
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ctx->blocksize_B = bcal_cipher_getBlocksize_b(desc) / 8;
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if (ctx->blocksize_B != 128 / 8 && ctx->blocksize_B != 64 / 8) {
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return 0x13;
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}
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ctx->accu = malloc(ctx->blocksize_B);
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if (ctx->accu == NULL) {
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return 0x14;
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}
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ctx->k1 = malloc(ctx->blocksize_B);
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if (ctx->k1 == NULL) {
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return 0x15;
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}
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ctx->k2 = malloc(ctx->blocksize_B);
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if (ctx->k2 == NULL) {
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return 0x16;
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}
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ctx->lastblock = malloc(ctx->blocksize_B);
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if (ctx->lastblock == NULL) {
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return 0x17;
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}
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r = bcal_cipher_init(desc, key, keysize_b, &(ctx->cctx));
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if (r) {
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return r;
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}
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if (ctx->blocksize_B == 128 / 8) {
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r = const_128;
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} else {
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r = const_64;
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}
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/* subkey computation */
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memset(ctx->accu, 0x00, ctx->blocksize_B);
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memset(ctx->k1, 0x00, ctx->blocksize_B);
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bcal_cipher_enc(ctx->k1, &(ctx->cctx));
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if (left_shift_be_block(ctx->k1, ctx->blocksize_B)) {
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ctx->k1[ctx->blocksize_B - 1] ^= r;
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}
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memcpy(ctx->k2, ctx->k1, ctx->blocksize_B);
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if (left_shift_be_block(ctx->k2, ctx->blocksize_B)) {
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ctx->k2[ctx->blocksize_B - 1] ^= r;
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}
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ctx->last_set = 0;
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return 0;
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}
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void bcal_cmac_free(bcal_cmac_ctx_t *ctx)
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{
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free(ctx->accu);
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free(ctx->k1);
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free(ctx->k2);
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bcal_cipher_free(&(ctx->cctx));
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}
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void bcal_cmac_nextBlock(bcal_cmac_ctx_t *ctx, const void *block)
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{
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if (ctx->last_set) {
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memxor(ctx->accu, ctx->lastblock, ctx->blocksize_B);
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bcal_cipher_enc(ctx->accu, &(ctx->cctx));
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}
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memcpy(ctx->lastblock, block, ctx->blocksize_B);
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ctx->last_set = 1;
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}
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void bcal_cmac_lastBlock(bcal_cmac_ctx_t *ctx, const void *block,
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uint16_t length_b)
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{
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uint16_t blocksize_b;
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blocksize_b = ctx->blocksize_B * 8;
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while (length_b >= blocksize_b) {
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bcal_cmac_nextBlock(ctx, block);
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block = (uint8_t*) block + ctx->blocksize_B;
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length_b -= blocksize_b;
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}
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if (ctx->last_set == 0) {
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memxor(ctx->accu, block, (length_b + 7) / 8);
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memxor(ctx->accu, ctx->k2, ctx->blocksize_B);
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ctx->accu[length_b / 8] ^= 0x80 >> (length_b & 7);
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} else {
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if (length_b == 0) {
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memxor(ctx->accu, ctx->lastblock, ctx->blocksize_B);
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memxor(ctx->accu, ctx->k1, ctx->blocksize_B);
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} else {
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memxor(ctx->accu, ctx->lastblock, ctx->blocksize_B);
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bcal_cipher_enc(ctx->accu, &(ctx->cctx));
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memxor(ctx->accu, block, (length_b + 7) / 8);
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memxor(ctx->accu, ctx->k2, ctx->blocksize_B);
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ctx->accu[length_b / 8] ^= 0x80 >> (length_b & 7);
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}
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}
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bcal_cipher_enc(ctx->accu, &(ctx->cctx));
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}
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void bcal_cmac_ctx2mac(void *dest, uint16_t length_b,
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const bcal_cmac_ctx_t *ctx)
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{
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memcpy(dest, ctx->accu, length_b / 8);
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if (length_b & 7) {
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((uint8_t*) dest)[length_b / 8] &= 0xff >> (length_b & 7);
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((uint8_t*) dest)[length_b / 8] |= (0xff00 >> (length_b & 7))
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& (ctx->accu[length_b / 8]);
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}
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}
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void bcal_cmac(void *dest, uint16_t out_length_b, const void *block,
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uint32_t length_b, bcal_cmac_ctx_t *ctx)
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{
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uint16_t blocksize_b;
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blocksize_b = ctx->blocksize_B * 8;
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while (length_b > blocksize_b) {
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bcal_cmac_nextBlock(ctx, block);
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block = (uint8_t*) block + ctx->blocksize_B;
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length_b -= blocksize_b;
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}
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bcal_cmac_lastBlock(ctx, block, length_b);
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bcal_cmac_ctx2mac(dest, out_length_b, ctx);
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}
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