bcal-cfb_bit.c

   1 /* bcal-cfb_bit.c */
   2 /*
   3     This file is part of the ARM-Crypto-Lib.
   4     Copyright (C) 2006-2010  Daniel Otte (daniel.otte@rub.de)
   5
   6     This program is free software: you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation, either version 3 of the License, or
   9     (at your option) any later version.
  10
  11     This program is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU General Public License for more details.
  15
  16     You should have received a copy of the GNU General Public License
  17     along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20
  21 #include <stdint.h>
  22 #include <string.h>
  23 #include "bcal-cfb_bit.h"
  24 #include "bcal-basic.h"
  25
  26 static uint8_t read_bit(void* block, uint32_t index){
  27         uint8_t r;
  28         r=((uint8_t*)block)[index/8];
  29         r=(r&(0x80>>(index&7)))?0xff:0x00;
  30         return r;
  31 }
  32
  33 static void write_bit(void* block, uint32_t index, uint8_t value){
  34         if(value){
  35                 /* set bit */
  36                 ((uint8_t*)block)[index/8] |= 0x80>>(index&7);
  37         }else{
  38                 /* clear bit */
  39                 ((uint8_t*)block)[index/8] &= ~(0x80>>(index&7));
  40         }
  41 }
  42
  43 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){
  44         ctx->desc = (bcdesc_t*)desc;
  45         ctx->blocksize_B = (bcal_cipher_getBlocksize_b(desc)+7)/8;
  46         ctx->in_block=malloc(ctx->blocksize_B);
  47         if(ctx->in_block==NULL){
  48                 return 0x11;
  49         }
  50         if(size_b>bcal_cipher_getBlocksize_b(desc)){
  51                 return 0x12;
  52         }
  53         ctx->size_b = size_b;
  54         return bcal_cipher_init(desc, key, keysize_b, &(ctx->cctx));
  55 }
  56
  57 void bcal_cfb_b_free(bcal_cfb_b_ctx_t* ctx){
  58         free(ctx->in_block);
  59         bcal_cipher_free(&(ctx->cctx));
  60 }
  61
  62 void bcal_cfb_b_loadIV(const void* iv, bcal_cfb_b_ctx_t* ctx){
  63         if(iv){
  64                 memcpy(ctx->in_block, iv, ctx->blocksize_B);
  65         }
  66 }
  67
  68 void bcal_cfb_b_encNext(void* block, uint8_t offset, bcal_cfb_b_ctx_t* ctx){
  69         uint8_t tmp[ctx->blocksize_B];
  70         offset &= 7;
  71         memcpy(tmp, ctx->in_block, ctx->blocksize_B);
  72         bcal_cipher_enc(tmp, &(ctx->cctx));
  73         uint16_t i,j;
  74         uint8_t a;
  75         for(i=0; i<ctx->blocksize_B*8-ctx->size_b; ++i){
  76                 a = read_bit(ctx->in_block, i+ctx->size_b);
  77                 write_bit(ctx->in_block, i, a);
  78         }
  79         for(j=offset,i=0; i<ctx->size_b; ++i, ++j){
  80                 a = read_bit(tmp, i) ^ read_bit(block, j);
  81                 write_bit(ctx->in_block, ctx->blocksize_B*8-ctx->size_b+i, a);
  82                 write_bit(block, j, a);
  83         }
  84 }
  85
  86 void bcal_cfb_b_decNext(void* block, uint8_t offset, bcal_cfb_b_ctx_t* ctx){
  87         uint8_t tmp[ctx->blocksize_B];
  88         offset &= 7;
  89         memcpy(tmp, ctx->in_block, ctx->blocksize_B);
  90         bcal_cipher_enc(tmp, &(ctx->cctx));
  91         uint16_t i,j;
  92         uint8_t a,b;
  93         for(i=0; i<ctx->blocksize_B*8-ctx->size_b; ++i){
  94                 a = read_bit(ctx->in_block, i+ctx->size_b);
  95                 write_bit(ctx->in_block, i, a);
  96         }
  97         for(j=offset,i=0; i<ctx->size_b; ++i, ++j){
  98                 a = read_bit(tmp, i);
  99                 b = read_bit(block, j);
 100                 a ^= b;
 101                 write_bit(ctx->in_block, ctx->blocksize_B*8-ctx->size_b+i, b);
 102                 write_bit(block, j, a);
 103         }
 104 }
 105
 106 void bcal_cfb_b_encMsg(const void* iv, void* msg, uint8_t offset, uint32_t msg_blocks, bcal_cfb_b_ctx_t* ctx){
 107         bcal_cfb_b_loadIV(iv, ctx);
 108         uint64_t addr;
 109         addr = ((uint32_t)msg)*8+offset;
 110         while(msg_blocks--){
 111                 msg = (void*)((uint32_t)(addr/8));
 112                 offset = addr&7;
 113                 bcal_cfb_b_encNext(msg, offset, ctx);
 114                 addr += ctx->size_b;
 115         }
 116 }
 117
 118 void bcal_cfb_b_decMsg(const void* iv, void* msg, uint8_t offset, uint32_t msg_blocks, bcal_cfb_b_ctx_t* ctx){
 119         bcal_cfb_b_loadIV(iv, ctx);
 120         uint64_t addr;
 121         addr = ((uint32_t)msg)*8+offset;
 122         while(msg_blocks--){
 123                 msg = (void*)((uint32_t)(addr/8));
 124                 offset = addr&7;
 125                 bcal_cfb_b_decNext(msg, offset, ctx);
 126                 addr += ctx->size_b;
 127         }
 128 }