git.zerfleddert.de Git - proxmark3-svn/blob - armsrc/optimized_cipher.h

   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
  38  #ifndef OPTIMIZED_CIPHER_H
  39 #define OPTIMIZED_CIPHER_H
  40 #include <stdint.h>
  41
  42 /**
  43 * Definition 1 (Cipher state). A cipher state of iClass s is an element of F 40/2
  44 * consisting of the following four components:
  45 *       1. the left register l = (l 0 . . . l 7 ) ∈ F 8/2 ;
  46 *       2. the right register r = (r 0 . . . r 7 ) ∈ F 8/2 ;
  47 *       3. the top register t = (t 0 . . . t 15 ) ∈ F 16/2 .
  48 *       4. the bottom register b = (b 0 . . . b 7 ) ∈ F 8/2 .
  49 **/
  50 typedef struct {
  51         uint8_t l;
  52         uint8_t r;
  53         uint8_t b;
  54         uint16_t t;
  55 } State;
  56
  57 /** The reader MAC is MAC(key, CC * NR )
  58  **/
  59 void opt_doReaderMAC(uint8_t *cc_nr_p, uint8_t *div_key_p, uint8_t mac[4]);
  60 /**
  61  * The tag MAC is MAC(key, CC * NR * 32x0))
  62  */
  63 void opt_doTagMAC(uint8_t *cc_p, const uint8_t *div_key_p, uint8_t mac[4]);
  64
  65 /**
  66  * The tag MAC can be divided (both can, but no point in dividing the reader mac) into
  67  * two functions, since the first 8 bytes are known, we can pre-calculate the state
  68  * reached after feeding CC to the cipher.
  69  * @param cc_p
  70  * @param div_key_p
  71  * @return the cipher state
  72  */
  73 State opt_doTagMAC_1(uint8_t *cc_p, const uint8_t *div_key_p);
  74 /**
  75  * The second part of the tag MAC calculation, since the CC is already calculated into the state,
  76  * this function is fed only the NR, and internally feeds the remaining 32 0-bits to generate the tag
  77  * MAC response.
  78  * @param _init - precalculated cipher state
  79  * @param nr - the reader challenge
  80  * @param mac - where to store the MAC
  81  * @param div_key_p - the key to use
  82  */
  83 void opt_doTagMAC_2(State _init, uint8_t* nr, uint8_t mac[4], const uint8_t* div_key_p);
  84
  85 #endif // OPTIMIZED_CIPHER_H