armsrc/cipherutils.c

   1 /*****************************************************************************
   2  * WARNING
   3  *
   4  * THIS CODE IS CREATED FOR EXPERIMENTATION AND EDUCATIONAL USE ONLY.
   5  *
   6  * USAGE OF THIS CODE IN OTHER WAYS MAY INFRINGE UPON THE INTELLECTUAL
   7  * PROPERTY OF OTHER PARTIES, SUCH AS INSIDE SECURE AND HID GLOBAL,
   8  * AND MAY EXPOSE YOU TO AN INFRINGEMENT ACTION FROM THOSE PARTIES.
   9  *
  10  * THIS CODE SHOULD NEVER BE USED TO INFRINGE PATENTS OR INTELLECTUAL PROPERTY RIGHTS.
  11  *
  12  *****************************************************************************
  13  *
  14  * This file is part of loclass. It is a reconstructon of the cipher engine
  15  * used in iClass, and RFID techology.
  16  *
  17  * The implementation is based on the work performed by
  18  * Flavio D. Garcia, Gerhard de Koning Gans, Roel Verdult and
  19  * Milosch Meriac in the paper "Dismantling IClass".
  20  *
  21  * Copyright (C) 2014 Martin Holst Swende
  22  *
  23  * This is free software: you can redistribute it and/or modify
  24  * it under the terms of the GNU General Public License version 2 as published
  25  * by the Free Software Foundation.
  26  *
  27  * This file is distributed in the hope that it will be useful,
  28  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  29  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  30  * GNU General Public License for more details.
  31  *
  32  * You should have received a copy of the GNU General Public License
  33  * along with loclass.  If not, see <http://www.gnu.org/licenses/>.
  34  *
  35  *
  36  *
  37  ****************************************************************************/
  38
  39 #include <stdint.h>
  40 #include <stdio.h>
  41 #include <string.h>
  42 #include "cipherutils.h"
  43 #ifndef ON_DEVICE
  44 #include "fileutils.h"
  45 #endif
  46 /**
  47  *
  48  * @brief Return and remove the first bit (x0) in the stream : <x0 x1 x2 x3 ... xn >
  49  * @param stream
  50  * @return
  51  */
  52 bool headBit( BitstreamIn *stream)
  53 {
  54         int bytepos = stream->position >> 3; // divide by 8
  55         int bitpos = (stream->position++) & 7; // mask out 00000111
  56         return (*(stream->buffer + bytepos) >> (7-bitpos)) & 1;
  57 }
  58 /**
  59  * @brief Return and remove the last bit (xn) in the stream: <x0 x1 x2 ... xn>
  60  * @param stream
  61  * @return
  62  */
  63 bool tailBit( BitstreamIn *stream)
  64 {
  65         int bitpos = stream->numbits -1 - (stream->position++);
  66
  67         int bytepos= bitpos >> 3;
  68         bitpos &= 7;
  69         return (*(stream->buffer + bytepos) >> (7-bitpos)) & 1;
  70 }
  71 /**
  72  * @brief Pushes bit onto the stream
  73  * @param stream
  74  * @param bit
  75  */
  76 void pushBit( BitstreamOut* stream, bool bit)
  77 {
  78         int bytepos = stream->position >> 3; // divide by 8
  79         int bitpos = stream->position & 7;
  80         *(stream->buffer+bytepos) |= (bit & 1) <<  (7 - bitpos);
  81         stream->position++;
  82         stream->numbits++;
  83 }
  84
  85 /**
  86  * @brief Pushes the lower six bits onto the stream
  87  * as b0 b1 b2 b3 b4 b5 b6
  88  * @param stream
  89  * @param bits
  90  */
  91 void push6bits( BitstreamOut* stream, uint8_t bits)
  92 {
  93         pushBit(stream, bits & 0x20);
  94         pushBit(stream, bits & 0x10);
  95         pushBit(stream, bits & 0x08);
  96         pushBit(stream, bits & 0x04);
  97         pushBit(stream, bits & 0x02);
  98         pushBit(stream, bits & 0x01);
  99 }
 100
 101 /**
 102  * @brief bitsLeft
 103  * @param stream
 104  * @return number of bits left in stream
 105  */
 106 int bitsLeft( BitstreamIn *stream)
 107 {
 108         return stream->numbits - stream->position;
 109 }
 110 /**
 111  * @brief numBits
 112  * @param stream
 113  * @return Number of bits stored in stream
 114  */
 115 int numBits(BitstreamOut *stream)
 116 {
 117         return stream->numbits;
 118 }
 119
 120 void x_num_to_bytes(uint64_t n, size_t len, uint8_t* dest)
 121 {
 122         while (len--) {
 123                 dest[len] = (uint8_t) n;
 124                 n >>= 8;
 125         }
 126 }
 127
 128 uint64_t x_bytes_to_num(uint8_t* src, size_t len)
 129 {
 130         uint64_t num = 0;
 131         while (len--)
 132         {
 133                 num = (num << 8) | (*src);
 134                 src++;
 135         }
 136         return num;
 137 }
 138 uint8_t reversebytes(uint8_t b) {
 139         b = (b & 0xF0) >> 4 | (b & 0x0F) << 4;
 140         b = (b & 0xCC) >> 2 | (b & 0x33) << 2;
 141         b = (b & 0xAA) >> 1 | (b & 0x55) << 1;
 142    return b;
 143 }
 144 void reverse_arraybytes(uint8_t* arr, size_t len)
 145 {
 146         uint8_t i;
 147         for( i =0; i< len ; i++)
 148         {
 149                 arr[i] = reversebytes(arr[i]);
 150         }
 151 }
 152 void reverse_arraycopy(uint8_t* arr, uint8_t* dest, size_t len)
 153 {
 154         uint8_t i;
 155         for( i =0; i< len ; i++)
 156         {
 157                 dest[i] = reversebytes(arr[i]);
 158         }
 159 }
 160 #ifndef ON_DEVICE
 161 void printarr(char * name, uint8_t* arr, int len)
 162 {
 163         int cx;
 164         size_t outsize = 40+strlen(name)+len*5;
 165         char* output = malloc(outsize);
 166         memset(output, 0,outsize);
 167
 168         int i ;
 169         cx = snprintf(output,outsize, "uint8_t %s[] = {", name);
 170         for(i =0 ;  i< len ; i++)
 171         {
 172                 cx += snprintf(output+cx,outsize-cx,"0x%02x,",*(arr+i));//5 bytes per byte
 173         }
 174         cx += snprintf(output+cx,outsize-cx,"};");
 175         prnlog(output);
 176 }
 177
 178 void printvar(char * name, uint8_t* arr, int len)
 179 {
 180         int cx;
 181         size_t outsize = 40+strlen(name)+len*2;
 182         char* output = malloc(outsize);
 183         memset(output, 0,outsize);
 184
 185         int i ;
 186         cx = snprintf(output,outsize,"%s = ", name);
 187         for(i =0 ;  i< len ; i++)
 188         {
 189                 cx += snprintf(output+cx,outsize-cx,"%02x",*(arr+i));//2 bytes per byte
 190         }
 191
 192         prnlog(output);
 193 }
 194
 195 void printarr_human_readable(char * title, uint8_t* arr, int len)
 196 {
 197         int cx;
 198         size_t outsize = 100+strlen(title)+len*4;
 199         char* output = malloc(outsize);
 200         memset(output, 0,outsize);
 201
 202
 203         int i;
 204         cx = snprintf(output,outsize,  "\n\t%s\n", title);
 205         for(i =0 ;  i< len ; i++)
 206         {
 207                 if(i % 16 == 0)
 208                         cx += snprintf(output+cx,outsize-cx,"\n%02x| ", i );
 209                 cx += snprintf(output+cx,outsize-cx, "%02x ",*(arr+i));
 210         }
 211         prnlog(output);
 212         free(output);
 213 }
 214 #endif
 215 //-----------------------------
 216 // Code for testing below
 217 //-----------------------------
 218
 219 #ifndef ON_DEVICE
 220 int testBitStream()
 221 {
 222         uint8_t input [] = {0xDE,0xAD,0xBE,0xEF,0xDE,0xAD,0xBE,0xEF};
 223         uint8_t output [] = {0,0,0,0,0,0,0,0};
 224         BitstreamIn in = { input, sizeof(input) * 8,0};
 225         BitstreamOut out ={ output, 0,0}
 226                                           ;
 227         while(bitsLeft(&in) > 0)
 228         {
 229                 pushBit(&out, headBit(&in));
 230                 //printf("Bits left: %d\n", bitsLeft(&in));
 231                 //printf("Bits out: %d\n", numBits(&out));
 232         }
 233         if(memcmp(input, output, sizeof(input)) == 0)
 234         {
 235                 prnlog("    Bitstream test 1 ok");
 236         }else
 237         {
 238                 prnlog("    Bitstream test 1 failed");
 239                 uint8_t i;
 240                 for(i = 0 ; i < sizeof(input) ; i++)
 241                 {
 242                         prnlog("    IN %02x, OUT %02x", input[i], output[i]);
 243                 }
 244                 return 1;
 245         }
 246         return 0;
 247 }
 248
 249 int testReversedBitstream()
 250 {
 251         uint8_t input [] = {0xDE,0xAD,0xBE,0xEF,0xDE,0xAD,0xBE,0xEF};
 252         uint8_t reverse [] = {0,0,0,0,0,0,0,0};
 253         uint8_t output [] = {0,0,0,0,0,0,0,0};
 254         BitstreamIn in = { input, sizeof(input) * 8,0};
 255         BitstreamOut out ={ output, 0,0};
 256         BitstreamIn reversed_in ={ reverse, sizeof(input)*8,0};
 257         BitstreamOut reversed_out ={ reverse,0 ,0};
 258
 259         while(bitsLeft(&in) > 0)
 260         {
 261                 pushBit(&reversed_out, tailBit(&in));
 262         }
 263         while(bitsLeft(&reversed_in) > 0)
 264         {
 265                 pushBit(&out, tailBit(&reversed_in));
 266         }
 267         if(memcmp(input, output, sizeof(input)) == 0)
 268         {
 269                 prnlog("    Bitstream test 2 ok");
 270         }else
 271         {
 272                 prnlog("    Bitstream test 2 failed");
 273                 uint8_t i;
 274                 for(i = 0 ; i < sizeof(input) ; i++)
 275                 {
 276                         prnlog("    IN %02x, MIDDLE: %02x, OUT %02x", input[i],reverse[i], output[i]);
 277                 }
 278                 return 1;
 279         }
 280         return 0;
 281 }
 282
 283
 284 int testCipherUtils(void)
 285 {
 286         prnlog("[+] Testing some internals...");
 287         int retval = 0;
 288         retval |= testBitStream();
 289         retval |= testReversedBitstream();
 290         return retval;
 291 }
 292 #endif