106 lines
2.9 KiB
C
106 lines
2.9 KiB
C
/* bcal-ctr.c */
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/*
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This file is part of the AVR-Crypto-Lib.
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Copyright (C) 2006-2015 Daniel Otte (bg@nerilex.org)
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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-ctr.h"
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#include "memxor.h"
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static void increment_be(void *block, uint8_t size_B)
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{
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uint16_t c = 1;
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do {
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--size_B;
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c += ((uint8_t*) block)[size_B];
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((uint8_t*) block)[size_B] = (uint8_t) c;
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c >>= 8;
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} while (size_B);
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}
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uint8_t bcal_ctr_init(const bcdesc_t *desc, const void *key, uint16_t keysize_b,
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inc_fp_t inc_func, bcal_ctr_ctx_t *ctx)
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{
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ctx->desc = (bcdesc_t*) desc;
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if (inc_func) {
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ctx->inc_func = inc_func;
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} else {
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ctx->inc_func = increment_be;
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}
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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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return bcal_cipher_init(desc, key, keysize_b, &(ctx->cctx));
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}
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void bcal_ctr_free(bcal_ctr_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_ctr_loadIV(const void *iv, bcal_ctr_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_ctr_encNext(void *block, bcal_ctr_ctx_t *ctx)
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{
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uint8_t tmp[ctx->blocksize_B];
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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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memxor(block, tmp, ctx->blocksize_B);
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ctx->inc_func(ctx->in_block, ctx->blocksize_B);
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}
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void bcal_ctr_decNext(void *block, bcal_ctr_ctx_t *ctx)
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{
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bcal_ctr_encNext(block, ctx);
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}
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void bcal_ctr_encMsg(const void *iv, void *msg, uint32_t msg_len_b,
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bcal_ctr_ctx_t *ctx)
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{
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bcal_ctr_loadIV(iv, ctx);
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uint16_t blocksize_b;
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blocksize_b = ctx->blocksize_B * 8;
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while (msg_len_b > blocksize_b) {
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bcal_ctr_encNext(msg, ctx);
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msg_len_b -= blocksize_b;
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msg = (uint8_t*) msg + ctx->blocksize_B;
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}
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uint8_t tmp[ctx->blocksize_B];
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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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ctx->inc_func(ctx->in_block, ctx->blocksize_B);
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tmp[msg_len_b / 8] = 0xff00 >> (msg_len_b & 7);
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memxor(msg, tmp, (msg_len_b + 7) / 8);
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}
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void bcal_ctr_decMsg(const void *iv, void *msg, uint32_t msg_len_b,
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bcal_ctr_ctx_t *ctx)
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{
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bcal_ctr_encMsg(iv, msg, msg_len_b, ctx);
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}
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