-/*****************************************************************************
- * WARNING
- *
- * THIS CODE IS CREATED FOR EXPERIMENTATION AND EDUCATIONAL USE ONLY.
- *
- * USAGE OF THIS CODE IN OTHER WAYS MAY INFRINGE UPON THE INTELLECTUAL
- * PROPERTY OF OTHER PARTIES, SUCH AS INSIDE SECURE AND HID GLOBAL,
- * AND MAY EXPOSE YOU TO AN INFRINGEMENT ACTION FROM THOSE PARTIES.
- *
- * THIS CODE SHOULD NEVER BE USED TO INFRINGE PATENTS OR INTELLECTUAL PROPERTY RIGHTS.
- *
- *****************************************************************************
- *
- * This file is part of loclass. It is a reconstructon of the cipher engine
- * used in iClass, and RFID techology.
- *
- * The implementation is based on the work performed by
- * Flavio D. Garcia, Gerhard de Koning Gans, Roel Verdult and
- * Milosch Meriac in the paper "Dismantling IClass".
- *
- * Copyright (C) 2014 Martin Holst Swende
- *
- * This is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as published
- * by the Free Software Foundation.
- *
- * This file is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with loclass. If not, see <http://www.gnu.org/licenses/>.
- *
- *
- *
- ****************************************************************************/
-
-
-#include "cipher.h"
-#include "cipherutils.h"
-#include <stdlib.h>
-#include <string.h>
-#include <stdbool.h>
-#include <stdint.h>
-#ifndef ON_DEVICE
-#include "fileutils.h"
-#endif
-
-
-/**
-* Definition 1 (Cipher state). A cipher state of iClass s is an element of F 40/2
-* consisting of the following four components:
-* 1. the left register l = (l 0 . . . l 7 ) ∈ F 8/2 ;
-* 2. the right register r = (r 0 . . . r 7 ) ∈ F 8/2 ;
-* 3. the top register t = (t 0 . . . t 15 ) ∈ F 16/2 .
-* 4. the bottom register b = (b 0 . . . b 7 ) ∈ F 8/2 .
-**/
-typedef struct {
- uint8_t l;
- uint8_t r;
- uint8_t b;
- uint16_t t;
-} State;
-
-/**
-* Definition 2. The feedback function for the top register T : F 16/2 → F 2
-* is defined as
-* T (x 0 x 1 . . . . . . x 15 ) = x 0 ⊕ x 1 ⊕ x 5 ⊕ x 7 ⊕ x 10 ⊕ x 11 ⊕ x 14 ⊕ x 15 .
-**/
-bool T(State state)
-{
- bool x0 = state.t & 0x8000;
- bool x1 = state.t & 0x4000;
- bool x5 = state.t & 0x0400;
- bool x7 = state.t & 0x0100;
- bool x10 = state.t & 0x0020;
- bool x11 = state.t & 0x0010;
- bool x14 = state.t & 0x0002;
- bool x15 = state.t & 0x0001;
- return x0 ^ x1 ^ x5 ^ x7 ^ x10 ^ x11 ^ x14 ^ x15;
-}
-/**
-* Similarly, the feedback function for the bottom register B : F 8/2 → F 2 is defined as
-* B(x 0 x 1 . . . x 7 ) = x 1 ⊕ x 2 ⊕ x 3 ⊕ x 7 .
-**/
-bool B(State state)
-{
- bool x1 = state.b & 0x40;
- bool x2 = state.b & 0x20;
- bool x3 = state.b & 0x10;
- bool x7 = state.b & 0x01;
-
- return x1 ^ x2 ^ x3 ^ x7;
-
-}
-
-
-/**
-* Definition 3 (Selection function). The selection function select : F 2 × F 2 ×
-* F 8/2 → F 3/2 is defined as select(x, y, r) = z 0 z 1 z 2 where
-* z 0 = (r 0 ∧ r 2 ) ⊕ (r 1 ∧ r 3 ) ⊕ (r 2 ∨ r 4 )
-* z 1 = (r 0 ∨ r 2 ) ⊕ (r 5 ∨ r 7 ) ⊕ r 1 ⊕ r 6 ⊕ x ⊕ y
-* z 2 = (r 3 ∧ r 5 ) ⊕ (r 4 ∧ r 6 ) ⊕ r 7 ⊕ x
-**/
-uint8_t _select(bool x, bool y, uint8_t r)
-{
- bool r0 = r >> 7 & 0x1;
- bool r1 = r >> 6 & 0x1;
- bool r2 = r >> 5 & 0x1;
- bool r3 = r >> 4 & 0x1;
- bool r4 = r >> 3 & 0x1;
- bool r5 = r >> 2 & 0x1;
- bool r6 = r >> 1 & 0x1;
- bool r7 = r & 0x1;
-
- bool z0 = (r0 & r2) ^ (r1 & ~r3) ^ (r2 | r4);
- bool z1 = (r0 | r2) ^ ( r5 | r7) ^ r1 ^ r6 ^ x ^ y;
- bool z2 = (r3 & ~r5) ^ (r4 & r6 ) ^ r7 ^ x;
-
- // The three bitz z0.. z1 are packed into a uint8_t:
- // 00000ZZZ
- //Return value is a uint8_t
- uint8_t retval = 0;
- retval |= (z0 << 2) & 4;
- retval |= (z1 << 1) & 2;
- retval |= z2 & 1;
-
- // Return value 0 <= retval <= 7
- return retval;
-}
-
-/**
-* Definition 4 (Successor state). Let s = l, r, t, b be a cipher state, k ∈ (F 82 ) 8
-* be a key and y ∈ F 2 be the input bit. Then, the successor cipher state s ′ =
-* l ′ , r ′ , t ′ , b ′ is defined as
-* t ′ := (T (t) ⊕ r 0 ⊕ r 4 )t 0 . . . t 14 l ′ := (k [select(T (t),y,r)] ⊕ b ′ ) ⊞ l ⊞ r
-* b ′ := (B(b) ⊕ r 7 )b 0 . . . b 6 r ′ := (k [select(T (t),y,r)] ⊕ b ′ ) ⊞ l
-*
-* @param s - state
-* @param k - array containing 8 bytes
-**/
-State successor(uint8_t* k, State s, bool y)
-{
- bool r0 = s.r >> 7 & 0x1;
- bool r4 = s.r >> 3 & 0x1;
- bool r7 = s.r & 0x1;
-
- State successor = {0,0,0,0};
-
- successor.t = s.t >> 1;
- successor.t |= (T(s) ^ r0 ^ r4) << 15;
-
- successor.b = s.b >> 1;
- successor.b |= (B(s) ^ r7) << 7;
-
- bool Tt = T(s);
-
- successor.l = ((k[_select(Tt,y,s.r)] ^ successor.b) + s.l+s.r ) & 0xFF;
- successor.r = ((k[_select(Tt,y,s.r)] ^ successor.b) + s.l ) & 0xFF;
-
- return successor;
-}
-/**
-* We define the successor function suc which takes a key k ∈ (F 82 ) 8 , a state s and
-* an input y ∈ F 2 and outputs the successor state s ′ . We overload the function suc
-* to multiple bit input x ∈ F n 2 which we define as
-* @param k - array containing 8 bytes
-**/
-State suc(uint8_t* k,State s, BitstreamIn *bitstream)
-{
- if(bitsLeft(bitstream) == 0)
- {
- return s;
- }
- bool lastbit = tailBit(bitstream);
- return successor(k,suc(k,s,bitstream), lastbit);
-}
-
-/**
-* Definition 5 (Output). Define the function output which takes an internal
-* state s =< l, r, t, b > and returns the bit r 5 . We also define the function output
-* on multiple bits input which takes a key k, a state s and an input x ∈ F n 2 as
-* output(k, s, ǫ) = ǫ
-* output(k, s, x 0 . . . x n ) = output(s) · output(k, s ′ , x 1 . . . x n )
-* where s ′ = suc(k, s, x 0 ).
-**/
-void output(uint8_t* k,State s, BitstreamIn* in, BitstreamOut* out)
-{
- if(bitsLeft(in) == 0)
- {
- return;
- }
- pushBit(out,(s.r >> 2) & 1);
- //Remove first bit
- uint8_t x0 = headBit(in);
- State ss = successor(k,s,x0);
- output(k,ss,in, out);
-}
-
-/**
-* Definition 6 (Initial state). Define the function init which takes as input a
-* key k ∈ (F 82 ) 8 and outputs the initial cipher state s =< l, r, t, b >
-**/
-
-State init(uint8_t* k)
-{
- State s = {
- ((k[0] ^ 0x4c) + 0xEC) & 0xFF,// l
- ((k[0] ^ 0x4c) + 0x21) & 0xFF,// r
- 0x4c, // b
- 0xE012 // t
- };
- return s;
-}
-void MAC(uint8_t* k, BitstreamIn input, BitstreamOut out)
-{
- uint8_t zeroes_32[] = {0,0,0,0};
- BitstreamIn input_32_zeroes = {zeroes_32,sizeof(zeroes_32)*8,0};
- State initState = suc(k,init(k),&input);
- output(k,initState,&input_32_zeroes,&out);
-}
-
-void doMAC(uint8_t *cc_nr_p, uint8_t *div_key_p, uint8_t mac[4])
-{
- uint8_t cc_nr[13] = { 0 };
- uint8_t div_key[8];
- //cc_nr=(uint8_t*)malloc(length+1);
-
- memcpy(cc_nr,cc_nr_p,12);
- memcpy(div_key,div_key_p,8);
-
- reverse_arraybytes(cc_nr,12);
- BitstreamIn bitstream = {cc_nr,12 * 8,0};
- uint8_t dest []= {0,0,0,0,0,0,0,0};
- BitstreamOut out = { dest, sizeof(dest)*8, 0 };
- MAC(div_key,bitstream, out);
- //The output MAC must also be reversed
- reverse_arraybytes(dest, sizeof(dest));
- memcpy(mac, dest, 4);
- //free(cc_nr);
- return;
-}
-#ifndef ON_DEVICE
-int testMAC()
-{
- prnlog("[+] Testing MAC calculation...");
-
- //From the "dismantling.IClass" paper:
- uint8_t cc_nr[] = {0xFE,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0,0,0,0};
- //From the paper
- uint8_t div_key[8] = {0xE0,0x33,0xCA,0x41,0x9A,0xEE,0x43,0xF9};
- uint8_t correct_MAC[4] = {0x1d,0x49,0xC9,0xDA};
-
- uint8_t calculated_mac[4] = {0};
- doMAC(cc_nr,div_key, calculated_mac);
-
- if(memcmp(calculated_mac, correct_MAC,4) == 0)
- {
- prnlog("[+] MAC calculation OK!");
-
- }else
- {
- prnlog("[+] FAILED: MAC calculation failed:");
- printarr(" Calculated_MAC", calculated_mac, 4);
- printarr(" Correct_MAC ", correct_MAC, 4);
- return 1;
- }
-
- return 0;
-}
-#endif
projects / proxmark3-svn / commitdiff