/* bcal-cfb_byte.c */
/*
 This file is part of the AVR-Crypto-Lib.
 Copyright (C) 2006-2015 Daniel Otte (bg@nerilex.org)

 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation, either version 3 of the License, or
 (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdint.h>
#include <string.h>
#include "bcal-cfb_byte.h"
#include "bcal-basic.h"
#include "memxor.h"

uint8_t bcal_cfb_B_init(const bcdesc_t *desc, const void *key,
        uint16_t keysize_b, uint16_t size_b, bcal_cfb_B_ctx_t *ctx)
{
    ctx->desc = (bcdesc_t*) desc;
    ctx->blocksize_B = (bcal_cipher_getBlocksize_b(desc) + 7) / 8;
    ctx->in_block = malloc(ctx->blocksize_B);
    if (ctx->in_block == NULL) {
        return 0x11;
    }
    if (size_b & 7) {
        return 0x12;
    }
    ctx->size_B = size_b / 8;
    return bcal_cipher_init(desc, key, keysize_b, &(ctx->cctx));
}

void bcal_cfb_B_free(bcal_cfb_B_ctx_t *ctx)
{
    free(ctx->in_block);
    bcal_cipher_free(&(ctx->cctx));
}

void bcal_cfb_B_loadIV(const void *iv, bcal_cfb_B_ctx_t *ctx)
{
    if (iv) {
        memcpy(ctx->in_block, iv, ctx->blocksize_B);
    }
}

void bcal_cfb_B_encNext(void *block, bcal_cfb_B_ctx_t *ctx)
{
    uint8_t tmp[ctx->blocksize_B];
    memcpy(tmp, ctx->in_block, ctx->blocksize_B);
    bcal_cipher_enc(tmp, &(ctx->cctx));
    memxor(block, tmp, ctx->size_B);
    memmove(ctx->in_block, ctx->in_block + ctx->size_B, ctx->blocksize_B
            - ctx->size_B);
    memcpy(ctx->in_block + ctx->blocksize_B - ctx->size_B, block, ctx->size_B);
}

void bcal_cfb_B_decNext(void *block, bcal_cfb_B_ctx_t *ctx)
{
    uint8_t tmp[ctx->blocksize_B];
    uint8_t xblock[ctx->size_B];
    memcpy(xblock, block, ctx->size_B);
    memcpy(tmp, ctx->in_block, ctx->blocksize_B);
    bcal_cipher_enc(tmp, &(ctx->cctx));
    memxor(block, tmp, ctx->size_B);
    memmove(ctx->in_block, ctx->in_block + ctx->size_B, ctx->blocksize_B
            - ctx->size_B);
    memcpy(ctx->in_block + ctx->blocksize_B - ctx->size_B, xblock, ctx->size_B);
}

void bcal_cfb_B_encMsg(const void *iv, void *msg, uint16_t msg_blocks,
        bcal_cfb_B_ctx_t *ctx)
{
    bcal_cfb_B_loadIV(iv, ctx);
    while (msg_blocks--) {
        bcal_cfb_B_encNext(msg, ctx);
        msg = (uint8_t*) msg + ctx->size_B;
    }
}

void bcal_cfb_B_decMsg(const void *iv, void *msg, uint16_t msg_blocks,
        bcal_cfb_B_ctx_t *ctx)
{
    bcal_cfb_B_loadIV(iv, ctx);
    while (msg_blocks--) {
        bcal_cfb_B_decNext(msg, ctx);
        msg = (uint8_t*) msg + ctx->size_B;
    }
}