cscipher/cscipher_small.c

   1 /* cscipher_small_core.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 #include <stdint.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include "memxor.h"
  24 #include "cscipher.h"
  25
  26 #define DEBUG 0
  27
  28 #if DEBUG
  29 #include "cli.h"
  30 #endif
  31
  32 #define ROTL(a) (((a)<<1)|((a)>>7))
  33
  34 #ifndef SBOX_PROG
  35 #define SBOX_PROG 0
  36 #endif
  37
  38 #if SBOX_PROG
  39 static const uint8_t fg_table[] = {
  40                 0xfa, 0xd6, 0xb0, 0xb2, 0x7b, 0x5e, 0x71, 0x78,
  41                 0xed, 0xd4, 0xa5, 0xb3, 0xef, 0xdc, 0xe7, 0xf9
  42 };
  43
  44 static
  45 uint8_t p(uint8_t a){
  46         a ^= fg_table[a&0xf]&0xf0;
  47         a ^= fg_table[a>>4] &0x0f;
  48         a ^= fg_table[a&0xf]&0xf0;
  49         return a;
  50 }
  51 #define P(a) p(a)
  52
  53 #else
  54
  55 #include "cscipher_sbox.h"
  56 #define P(a) (cscipher_sbox[(a)])
  57 #endif
  58
  59 static const uint8_t round_const[] = {
  60         0xb7, 0xe1, 0x51, 0x62, 0x8a, 0xed, 0x2a, 0x6a,
  61         0xbf, 0x71, 0x58, 0x80, 0x9c, 0xf4, 0xf3, 0xc7 };
  62
  63 static const uint8_t ks_const[] = {
  64         0x29,0x0d,0x61,0x40,0x9c,0xeb,0x9e,0x8f,
  65         0x1f,0x85,0x5f,0x58,0x5b,0x01,0x39,0x86,
  66         0x97,0x2e,0xd7,0xd6,0x35,0xae,0x17,0x16,
  67         0x21,0xb6,0x69,0x4e,0xa5,0x72,0x87,0x08,
  68         0x3c,0x18,0xe6,0xe7,0xfa,0xad,0xb8,0x89,
  69         0xb7,0x00,0xf7,0x6f,0x73,0x84,0x11,0x63,
  70         0x3f,0x96,0x7f,0x6e,0xbf,0x14,0x9d,0xac,
  71         0xa4,0x0e,0x7e,0xf6,0x20,0x4a,0x62,0x30,
  72         0x03,0xc5,0x4b,0x5a,0x46,0xa3,0x44,0x65
  73 };
  74
  75 static uint16_t m(uint16_t a){
  76         uint8_t xl, xr, yl, yr;
  77         uint16_t ret;
  78         xr = a>>8;
  79         xl = a&0xff;
  80         yl = (ROTL(xl)&0x55)^xl^xr;
  81         yr = ROTL(xl)^xr;
  82         ret = (P(yr)<<8)|P(yl);
  83         return ret;
  84 }
  85
  86 static uint16_t m_inv(uint16_t a){
  87         uint8_t xl, xr;
  88         xr = P(a>>8);
  89         xl = P(a&0xff);
  90         xl ^= xr;
  91         xl ^= (ROTL(xl)&0xaa);
  92         xr ^= ROTL(xl);
  93         return (xr<<8)|xl;
  94 }
  95
  96
  97 void cscipher_enc(void* buffer, const cscipher_ctx_t* ctx){
  98         uint8_t i,j,k;
  99         uint8_t tmp[8];
 100         for(i=0; i<8; ++i){
 101 #if DEBUG
 102                 cli_putstr("\r\nDBG: round ");
 103                 cli_hexdump(&i, 1);
 104                 cli_putstr(" buffer:");
 105                 cli_hexdump(buffer, 8);
 106 #endif
 107                 for(j=0; j<3; ++j){
 108                         if(j==0){
 109                                 memxor(buffer, ctx->keys[i], 8);
 110                         }else{
 111                                 memxor(buffer, round_const+((j==1)?0:8), 8);
 112                         }
 113                         for(k=0; k<4; ++k){
 114                                 ((uint16_t*)tmp)[k] = m(((uint16_t*)buffer)[k]);
 115                         }
 116                         for(k=0; k<4; ++k){
 117                                 ((uint8_t*)buffer)[k]   = tmp[2*k];
 118                                 ((uint8_t*)buffer)[k+4] = tmp[2*k+1];
 119                         }
 120                 }
 121         }
 122         memxor(buffer, ctx->keys[8], 8);
 123 }
 124
 125 void cscipher_dec(void* buffer, const cscipher_ctx_t* ctx){
 126         uint8_t i=7,j,k;
 127         uint8_t tmp[8];
 128         memxor(buffer, ctx->keys[8], 8);
 129         do{
 130                 for(j=0; j<3; ++j){
 131                         for(k=0; k<4; ++k){
 132                                 tmp[2*k]   = ((uint8_t*)buffer)[k];
 133                                 tmp[2*k+1] = ((uint8_t*)buffer)[4+k];
 134                         }
 135                         for(k=0; k<4; ++k){
 136                                 ((uint16_t*)buffer)[k] = m_inv(((uint16_t*)tmp)[k]);
 137                         }
 138                         if(j==2){
 139                                 memxor(buffer, ctx->keys[i], 8);
 140                         }else{
 141                                 memxor(buffer, round_const+((j==1)?0:8), 8);
 142                         }
 143
 144                 }
 145         }while(i--);
 146 }
 147
 148 void cscipher_init(const void* key, cscipher_ctx_t* ctx){
 149         uint8_t tmp_key[16], tmp[8];
 150         uint8_t i,j,k,t=0;
 151         memcpy(tmp_key, key, 16);
 152         for(i=0; i<9; ++i){
 153 #if DEBUG
 154                 cli_putstr("\r\nDBG: round ");
 155                 cli_hexdump(&i, 1);
 156                 cli_putstr(" key state:");
 157                 cli_hexdump(tmp_key, 16);
 158 #endif
 159                 memcpy(tmp, tmp_key+(((i&1)==0)?0:8), 8);
 160                 memxor(tmp, ks_const+8*i, 8);
 161                 for(j=0; j<8; ++j){
 162                         tmp[j] = P(tmp[j]);
 163                 }
 164                 for(j=0; j<8; ++j){
 165                         for(k=0; k<8; ++k){
 166                                 t<<=1;
 167                                 t |= tmp[k]>>7;
 168                                 tmp[k]<<=1;
 169                         }
 170                         tmp_key[j+(((i&1)==0)?8:0)] ^= t;
 171                 }
 172                 memcpy(ctx->keys[i], tmp_key+(((i&1)==0)?8:0), 8);
 173         }
 174 }