armsrc/optimized_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, or, at your option, any later version.
  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 #include "optimized_cipherutils.h"
  38 #include <stdint.h>
  39
  40 /**
  41  *
  42  * @brief Return and remove the first bit (x0) in the stream : <x0 x1 x2 x3 ... xn >
  43  * @param stream
  44  * @return
  45  */
  46 bool headBit(BitstreamIn *stream) {
  47     int bytepos = stream->position >> 3; // divide by 8
  48     int bitpos = (stream->position++) & 7; // mask out 00000111
  49     return (*(stream->buffer + bytepos) >> (7 - bitpos)) & 1;
  50 }
  51 /**
  52  * @brief Return and remove the last bit (xn) in the stream: <x0 x1 x2 ... xn>
  53  * @param stream
  54  * @return
  55  */
  56 bool tailBit(BitstreamIn *stream) {
  57     int bitpos = stream->numbits - 1 - (stream->position++);
  58
  59     int bytepos = bitpos >> 3;
  60     bitpos &= 7;
  61     return (*(stream->buffer + bytepos) >> (7 - bitpos)) & 1;
  62 }
  63 /**
  64  * @brief Pushes bit onto the stream
  65  * @param stream
  66  * @param bit
  67  */
  68 void pushBit(BitstreamOut *stream, bool bit) {
  69     int bytepos = stream->position >> 3; // divide by 8
  70     int bitpos = stream->position & 7;
  71     *(stream->buffer + bytepos) |= (bit) << (7 - bitpos);
  72     stream->position++;
  73     stream->numbits++;
  74 }
  75
  76 /**
  77  * @brief Pushes the lower six bits onto the stream
  78  * as b0 b1 b2 b3 b4 b5 b6
  79  * @param stream
  80  * @param bits
  81  */
  82 void push6bits(BitstreamOut *stream, uint8_t bits) {
  83     pushBit(stream, bits & 0x20);
  84     pushBit(stream, bits & 0x10);
  85     pushBit(stream, bits & 0x08);
  86     pushBit(stream, bits & 0x04);
  87     pushBit(stream, bits & 0x02);
  88     pushBit(stream, bits & 0x01);
  89 }
  90
  91 /**
  92  * @brief bitsLeft
  93  * @param stream
  94  * @return number of bits left in stream
  95  */
  96 int bitsLeft(BitstreamIn *stream) {
  97     return stream->numbits - stream->position;
  98 }
  99 /**
 100  * @brief numBits
 101  * @param stream
 102  * @return Number of bits stored in stream
 103  */
 104 void x_num_to_bytes(uint64_t n, size_t len, uint8_t *dest) {
 105     while (len--) {
 106         dest[len] = (uint8_t) n;
 107         n >>= 8;
 108     }
 109 }
 110
 111 uint64_t x_bytes_to_num(uint8_t *src, size_t len) {
 112     uint64_t num = 0;
 113     while (len--) {
 114         num = (num << 8) | (*src);
 115         src++;
 116     }
 117     return num;
 118 }
 119
 120 uint8_t reversebytes(uint8_t b) {
 121     b = (b & 0xF0) >> 4 | (b & 0x0F) << 4;
 122     b = (b & 0xCC) >> 2 | (b & 0x33) << 2;
 123     b = (b & 0xAA) >> 1 | (b & 0x55) << 1;
 124     return b;
 125 }
 126
 127 void reverse_arraybytes(uint8_t *arr, size_t len) {
 128     uint8_t i;
 129     for (i = 0; i < len ; i++) {
 130         arr[i] = reversebytes(arr[i]);
 131     }
 132 }
 133
 134 void reverse_arraycopy(uint8_t *arr, uint8_t *dest, size_t len) {
 135     uint8_t i;
 136     for (i = 0; i < len ; i++) {
 137         dest[i] = reversebytes(arr[i]);
 138     }
 139 }
 140