update books to app_areas. clearer.
[proxmark3-svn] / client / loclass / cipher.c
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a66fca86 1/*****************************************************************************
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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
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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
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33 * along with loclass. If not, see <http://www.gnu.org/licenses/>.
34 *
35 *
36 *
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37 ****************************************************************************/
38
d60418a0 39
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40#include "cipher.h"
41#include "cipherutils.h"
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42#include <stdlib.h>
43#include <string.h>
44#include <stdbool.h>
45#include <stdint.h>
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46#ifndef ON_DEVICE
47#include "fileutils.h"
48#endif
49
a66fca86 50
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51/**
52* Definition 1 (Cipher state). A cipher state of iClass s is an element of F 40/2
53* consisting of the following four components:
54* 1. the left register l = (l 0 . . . l 7 ) ∈ F 8/2 ;
55* 2. the right register r = (r 0 . . . r 7 ) ∈ F 8/2 ;
56* 3. the top register t = (t 0 . . . t 15 ) ∈ F 16/2 .
57* 4. the bottom register b = (b 0 . . . b 7 ) ∈ F 8/2 .
58**/
59typedef struct {
60 uint8_t l;
61 uint8_t r;
62 uint8_t b;
63 uint16_t t;
64} State;
65
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66/**
67* Definition 2. The feedback function for the top register T : F 16/2 → F 2
68* is defined as
69* T (x 0 x 1 . . . . . . x 15 ) = x 0 ⊕ x 1 ⊕ x 5 ⊕ x 7 ⊕ x 10 ⊕ x 11 ⊕ x 14 ⊕ x 15 .
70**/
71bool T(State state)
72{
73 bool x0 = state.t & 0x8000;
74 bool x1 = state.t & 0x4000;
75 bool x5 = state.t & 0x0400;
76 bool x7 = state.t & 0x0100;
77 bool x10 = state.t & 0x0020;
78 bool x11 = state.t & 0x0010;
79 bool x14 = state.t & 0x0002;
80 bool x15 = state.t & 0x0001;
81 return x0 ^ x1 ^ x5 ^ x7 ^ x10 ^ x11 ^ x14 ^ x15;
82}
83/**
84* Similarly, the feedback function for the bottom register B : F 8/2 → F 2 is defined as
85* B(x 0 x 1 . . . x 7 ) = x 1 ⊕ x 2 ⊕ x 3 ⊕ x 7 .
86**/
87bool B(State state)
88{
89 bool x1 = state.b & 0x40;
90 bool x2 = state.b & 0x20;
91 bool x3 = state.b & 0x10;
92 bool x7 = state.b & 0x01;
93
94 return x1 ^ x2 ^ x3 ^ x7;
95
96}
97
98
99/**
100* Definition 3 (Selection function). The selection function select : F 2 × F 2 ×
101* F 8/2 → F 3/2 is defined as select(x, y, r) = z 0 z 1 z 2 where
102* z 0 = (r 0 ∧ r 2 ) ⊕ (r 1 ∧ r 3 ) ⊕ (r 2 ∨ r 4 )
103* z 1 = (r 0 ∨ r 2 ) ⊕ (r 5 ∨ r 7 ) ⊕ r 1 ⊕ r 6 ⊕ x ⊕ y
104* z 2 = (r 3 ∧ r 5 ) ⊕ (r 4 ∧ r 6 ) ⊕ r 7 ⊕ x
105**/
106uint8_t _select(bool x, bool y, uint8_t r)
107{
108 bool r0 = r >> 7 & 0x1;
109 bool r1 = r >> 6 & 0x1;
110 bool r2 = r >> 5 & 0x1;
111 bool r3 = r >> 4 & 0x1;
112 bool r4 = r >> 3 & 0x1;
113 bool r5 = r >> 2 & 0x1;
114 bool r6 = r >> 1 & 0x1;
115 bool r7 = r & 0x1;
116
117 bool z0 = (r0 & r2) ^ (r1 & ~r3) ^ (r2 | r4);
118 bool z1 = (r0 | r2) ^ ( r5 | r7) ^ r1 ^ r6 ^ x ^ y;
119 bool z2 = (r3 & ~r5) ^ (r4 & r6 ) ^ r7 ^ x;
120
121 // The three bitz z0.. z1 are packed into a uint8_t:
122 // 00000ZZZ
123 //Return value is a uint8_t
124 uint8_t retval = 0;
125 retval |= (z0 << 2) & 4;
126 retval |= (z1 << 1) & 2;
127 retval |= z2 & 1;
128
129 // Return value 0 <= retval <= 7
130 return retval;
131}
132
133/**
134* Definition 4 (Successor state). Let s = l, r, t, b be a cipher state, k ∈ (F 82 ) 8
135* be a key and y ∈ F 2 be the input bit. Then, the successor cipher state s ′ =
136* l ′ , r ′ , t ′ , b ′ is defined as
137* t ′ := (T (t) ⊕ r 0 ⊕ r 4 )t 0 . . . t 14 l ′ := (k [select(T (t),y,r)] ⊕ b ′ ) ⊞ l ⊞ r
138* b ′ := (B(b) ⊕ r 7 )b 0 . . . b 6 r ′ := (k [select(T (t),y,r)] ⊕ b ′ ) ⊞ l
139*
140* @param s - state
141* @param k - array containing 8 bytes
142**/
143State successor(uint8_t* k, State s, bool y)
144{
145 bool r0 = s.r >> 7 & 0x1;
146 bool r4 = s.r >> 3 & 0x1;
147 bool r7 = s.r & 0x1;
148
149 State successor = {0,0,0,0};
150
151 successor.t = s.t >> 1;
152 successor.t |= (T(s) ^ r0 ^ r4) << 15;
153
154 successor.b = s.b >> 1;
155 successor.b |= (B(s) ^ r7) << 7;
156
157 bool Tt = T(s);
158
159 successor.l = ((k[_select(Tt,y,s.r)] ^ successor.b) + s.l+s.r ) & 0xFF;
160 successor.r = ((k[_select(Tt,y,s.r)] ^ successor.b) + s.l ) & 0xFF;
161
162 return successor;
163}
164/**
165* We define the successor function suc which takes a key k ∈ (F 82 ) 8 , a state s and
166* an input y ∈ F 2 and outputs the successor state s ′ . We overload the function suc
167* to multiple bit input x ∈ F n 2 which we define as
168* @param k - array containing 8 bytes
169**/
170State suc(uint8_t* k,State s, BitstreamIn *bitstream)
171{
172 if(bitsLeft(bitstream) == 0)
173 {
174 return s;
175 }
176 bool lastbit = tailBit(bitstream);
177 return successor(k,suc(k,s,bitstream), lastbit);
178}
179
180/**
181* Definition 5 (Output). Define the function output which takes an internal
182* state s =< l, r, t, b > and returns the bit r 5 . We also define the function output
183* on multiple bits input which takes a key k, a state s and an input x ∈ F n 2 as
184* output(k, s, ǫ) = ǫ
185* output(k, s, x 0 . . . x n ) = output(s) · output(k, s ′ , x 1 . . . x n )
186* where s ′ = suc(k, s, x 0 ).
187**/
188void output(uint8_t* k,State s, BitstreamIn* in, BitstreamOut* out)
189{
190 if(bitsLeft(in) == 0)
191 {
192 return;
193 }
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194 pushBit(out,(s.r >> 2) & 1);
195 //Remove first bit
196 uint8_t x0 = headBit(in);
197 State ss = successor(k,s,x0);
198 output(k,ss,in, out);
199}
200
201/**
202* Definition 6 (Initial state). Define the function init which takes as input a
203* key k ∈ (F 82 ) 8 and outputs the initial cipher state s =< l, r, t, b >
204**/
205
206State init(uint8_t* k)
207{
208 State s = {
209 ((k[0] ^ 0x4c) + 0xEC) & 0xFF,// l
210 ((k[0] ^ 0x4c) + 0x21) & 0xFF,// r
211 0x4c, // b
212 0xE012 // t
213 };
214 return s;
215}
216void MAC(uint8_t* k, BitstreamIn input, BitstreamOut out)
217{
218 uint8_t zeroes_32[] = {0,0,0,0};
219 BitstreamIn input_32_zeroes = {zeroes_32,sizeof(zeroes_32)*8,0};
220 State initState = suc(k,init(k),&input);
221 output(k,initState,&input_32_zeroes,&out);
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222}
223
b67f7ec3 224void doMAC(uint8_t *cc_nr_p, uint8_t *div_key_p, uint8_t mac[4])
a66fca86 225{
b67f7ec3 226 uint8_t cc_nr[13] = { 0 };
74a38802 227 uint8_t div_key[8];
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228 //cc_nr=(uint8_t*)malloc(length+1);
229
230 memcpy(cc_nr,cc_nr_p,12);
74a38802 231 memcpy(div_key,div_key_p,8);
aa41c605 232
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233 reverse_arraybytes(cc_nr,12);
234 BitstreamIn bitstream = {cc_nr,12 * 8,0};
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235 uint8_t dest []= {0,0,0,0,0,0,0,0};
236 BitstreamOut out = { dest, sizeof(dest)*8, 0 };
237 MAC(div_key,bitstream, out);
238 //The output MAC must also be reversed
239 reverse_arraybytes(dest, sizeof(dest));
aa41c605 240 memcpy(mac, dest, 4);
b67f7ec3 241 //free(cc_nr);
aa41c605 242 return;
a66fca86 243}
aa53efc3 244void doMAC_N(uint8_t *cc_nr_p,uint8_t cc_nr_size, uint8_t *div_key_p, uint8_t mac[4])
245{
246 uint8_t *cc_nr;
247 uint8_t div_key[8];
248 cc_nr = (uint8_t*) malloc(cc_nr_size);
249
250 memcpy(cc_nr,cc_nr_p,cc_nr_size);
251 memcpy(div_key,div_key_p,8);
252
253 reverse_arraybytes(cc_nr,cc_nr_size);
254 BitstreamIn bitstream = {cc_nr,cc_nr_size * 8,0};
255 uint8_t dest []= {0,0,0,0,0,0,0,0};
256 BitstreamOut out = { dest, sizeof(dest)*8, 0 };
257 MAC(div_key,bitstream, out);
258 //The output MAC must also be reversed
259 reverse_arraybytes(dest, sizeof(dest));
260 memcpy(mac, dest, 4);
261 free(cc_nr);
262 return;
263}
264
b67f7ec3 265#ifndef ON_DEVICE
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266int testMAC()
267{
3ad48540 268 prnlog("[+] Testing MAC calculation...");
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269
270 //From the "dismantling.IClass" paper:
271 uint8_t cc_nr[] = {0xFE,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0,0,0,0};
a66fca86 272 //From the paper
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273 uint8_t div_key[8] = {0xE0,0x33,0xCA,0x41,0x9A,0xEE,0x43,0xF9};
274 uint8_t correct_MAC[4] = {0x1d,0x49,0xC9,0xDA};
a66fca86 275
3ad48540 276 uint8_t calculated_mac[4] = {0};
b67f7ec3 277 doMAC(cc_nr,div_key, calculated_mac);
a66fca86 278
3ad48540 279 if(memcmp(calculated_mac, correct_MAC,4) == 0)
a66fca86 280 {
3ad48540 281 prnlog("[+] MAC calculation OK!");
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282
283 }else
284 {
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285 prnlog("[+] FAILED: MAC calculation failed:");
286 printarr(" Calculated_MAC", calculated_mac, 4);
287 printarr(" Correct_MAC ", correct_MAC, 4);
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288 return 1;
289 }
3ad48540 290
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291 return 0;
292}
b67f7ec3 293#endif
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