140 lines
4.1 KiB
C
140 lines
4.1 KiB
C
/* bcal-cfb_bit.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-cfb_bit.h"
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#include "bcal-basic.h"
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static uint8_t read_bit(void *block, uint32_t index)
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{
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uint8_t r;
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r = ((uint8_t*) block)[index / 8];
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r = (r & (0x80 >> (index & 7))) ? 0xff : 0x00;
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return r;
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}
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static void write_bit(void *block, uint32_t index, uint8_t value)
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{
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if (value) {
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/* set bit */
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((uint8_t*) block)[index / 8] |= 0x80 >> (index & 7);
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} else {
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/* clear bit */
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((uint8_t*) block)[index / 8] &= ~(0x80 >> (index & 7));
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}
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}
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uint8_t bcal_cfb_b_init(const bcdesc_t *desc, const void *key,
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uint16_t keysize_b, uint16_t size_b, bcal_cfb_b_ctx_t *ctx)
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{
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ctx->desc = (bcdesc_t*) desc;
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ctx->blocksize_B = (bcal_cipher_getBlocksize_b(desc) + 7) / 8;
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ctx->in_block = malloc(ctx->blocksize_B);
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if (ctx->in_block == NULL) {
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return 0x11;
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}
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if (size_b > bcal_cipher_getBlocksize_b(desc)) {
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return 0x12;
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}
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ctx->size_b = size_b;
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return bcal_cipher_init(desc, key, keysize_b, &(ctx->cctx));
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}
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void bcal_cfb_b_free(bcal_cfb_b_ctx_t *ctx)
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{
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free(ctx->in_block);
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bcal_cipher_free(&(ctx->cctx));
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}
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void bcal_cfb_b_loadIV(const void *iv, bcal_cfb_b_ctx_t *ctx)
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{
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if (iv) {
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memcpy(ctx->in_block, iv, ctx->blocksize_B);
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}
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}
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void bcal_cfb_b_encNext(void *block, uint8_t offset, bcal_cfb_b_ctx_t *ctx)
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{
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uint8_t tmp[ctx->blocksize_B];
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offset &= 7;
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memcpy(tmp, ctx->in_block, ctx->blocksize_B);
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bcal_cipher_enc(tmp, &(ctx->cctx));
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uint16_t i, j;
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uint8_t a;
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for (i = 0; i < ctx->blocksize_B * 8 - ctx->size_b; ++i) {
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a = read_bit(ctx->in_block, i + ctx->size_b);
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write_bit(ctx->in_block, i, a);
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}
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for (j = offset, i = 0; i < ctx->size_b; ++i, ++j) {
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a = read_bit(tmp, i) ^ read_bit(block, j);
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write_bit(ctx->in_block, ctx->blocksize_B * 8 - ctx->size_b + i, a);
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write_bit(block, j, a);
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}
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}
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void bcal_cfb_b_decNext(void *block, uint8_t offset, bcal_cfb_b_ctx_t *ctx)
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{
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uint8_t tmp[ctx->blocksize_B];
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offset &= 7;
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memcpy(tmp, ctx->in_block, ctx->blocksize_B);
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bcal_cipher_enc(tmp, &(ctx->cctx));
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uint16_t i, j;
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uint8_t a, b;
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for (i = 0; i < ctx->blocksize_B * 8 - ctx->size_b; ++i) {
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a = read_bit(ctx->in_block, i + ctx->size_b);
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write_bit(ctx->in_block, i, a);
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}
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for (j = offset, i = 0; i < ctx->size_b; ++i, ++j) {
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a = read_bit(tmp, i);
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b = read_bit(block, j);
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a ^= b;
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write_bit(ctx->in_block, ctx->blocksize_B * 8 - ctx->size_b + i, b);
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write_bit(block, j, a);
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}
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}
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void bcal_cfb_b_encMsg(const void *iv, void *msg, uint8_t offset,
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uint32_t msg_blocks, bcal_cfb_b_ctx_t *ctx)
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{
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bcal_cfb_b_loadIV(iv, ctx);
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uint32_t addr;
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addr = ((uint16_t) msg) * 8 + offset;
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while (msg_blocks--) {
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msg = (void*) ((uint16_t) (addr / 8));
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offset = addr & 7;
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bcal_cfb_b_encNext(msg, offset, ctx);
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addr += ctx->size_b;
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}
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}
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void bcal_cfb_b_decMsg(const void *iv, void *msg, uint8_t offset,
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uint32_t msg_blocks, bcal_cfb_b_ctx_t *ctx)
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{
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bcal_cfb_b_loadIV(iv, ctx);
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uint32_t addr;
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addr = ((uint16_t) msg) * 8 + offset;
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while (msg_blocks--) {
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msg = (void*) ((uint16_t) (addr / 8));
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offset = addr & 7;
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bcal_cfb_b_decNext(msg, offset, ctx);
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addr += ctx->size_b;
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}
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}
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