Added the ciphers also.. doh
[proxmark3-svn] / armsrc / optimized_cipher.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 /**
40
41 This file contains an optimized version of the MAC-calculation algorithm. Some measurements on
42 a std laptop showed it runs in about 1/3 of the time:
43
44 Std: 0.428962
45 Opt: 0.151609
46
47 Additionally, it is self-reliant, not requiring e.g. bitstreams from the cipherutils, thus can
48 be easily dropped into a code base.
49
50 The optimizations have been performed in the following steps:
51 * Parameters passed by reference instead of by value.
52 * Iteration instead of recursion, un-nesting recursive loops into for-loops.
53 * Handling of bytes instead of individual bits, for less shuffling and masking
54 * Less creation of "objects", structs, and instead reuse of alloc:ed memory
55 * Inlining some functions via #define:s
56
57 As a consequence, this implementation is less generic. Also, I haven't bothered documenting this.
58 For a thorough documentation, check out the MAC-calculation within cipher.c instead.
59
60 -- MHS 2015
61 **/
62
63 #include "optimized_cipher.h"
64 #include <stdio.h>
65 #include <stdlib.h>
66 #include <string.h>
67 #include <stdbool.h>
68 #include <stdint.h>
69 #include <time.h>
70
71 /**
72 * Definition 1 (Cipher state). A cipher state of iClass s is an element of F 40/2
73 * consisting of the following four components:
74 * 1. the left register l = (l 0 . . . l 7 ) ∈ F 8/2 ;
75 * 2. the right register r = (r 0 . . . r 7 ) ∈ F 8/2 ;
76 * 3. the top register t = (t 0 . . . t 15 ) ∈ F 16/2 .
77 * 4. the bottom register b = (b 0 . . . b 7 ) ∈ F 8/2 .
78 **/
79 typedef struct {
80 uint8_t l;
81 uint8_t r;
82 uint8_t b;
83 uint16_t t;
84 } State;
85
86
87 #define opt_T(s) (0x1 & ((s->t >> 15) ^ (s->t >> 14)^ (s->t >> 10)^ (s->t >> 8)^ (s->t >> 5)^ (s->t >> 4)^ (s->t >> 1)^ s->t))
88
89 #define opt_B(s) (((s->b >> 6) ^ (s->b >> 5) ^ (s->b >> 4) ^ (s->b)) & 0x1)
90
91 #define opt__select(x,y,r) (4 & (((r & (r << 2)) >> 5) ^ ((r & ~(r << 2)) >> 4) ^ ( (r | r << 2) >> 3)))\
92 |(2 & (((r | r << 2) >> 6) ^ ( (r | r << 2) >> 1) ^ (r >> 5) ^ r ^ ((x^y) << 1)))\
93 |(1 & (((r & ~(r << 2)) >> 4) ^ ((r & (r << 2)) >> 3) ^ r ^ x))
94
95 /*
96 * Some background on the expression above can be found here...
97 uint8_t xopt__select(bool x, bool y, uint8_t r)
98 {
99 uint8_t r_ls2 = r << 2;
100 uint8_t r_and_ls2 = r & r_ls2;
101 uint8_t r_or_ls2 = r | r_ls2;
102
103 //r: r0 r1 r2 r3 r4 r5 r6 r7
104 //r_ls2: r2 r3 r4 r5 r6 r7 0 0
105 // z0
106 // z1
107
108 // uint8_t z0 = (r0 & r2) ^ (r1 & ~r3) ^ (r2 | r4); // <-- original
109 uint8_t z0 = (r_and_ls2 >> 5) ^ ((r & ~r_ls2) >> 4) ^ ( r_or_ls2 >> 3);
110
111 // uint8_t z1 = (r0 | r2) ^ ( r5 | r7) ^ r1 ^ r6 ^ x ^ y; // <-- original
112 uint8_t z1 = (r_or_ls2 >> 6) ^ ( r_or_ls2 >> 1) ^ (r >> 5) ^ r ^ ((x^y) << 1);
113
114 // uint8_t z2 = (r3 & ~r5) ^ (r4 & r6 ) ^ r7 ^ x; // <-- original
115 uint8_t z2 = ((r & ~r_ls2) >> 4) ^ (r_and_ls2 >> 3) ^ r ^ x;
116
117 return (z0 & 4) | (z1 & 2) | (z2 & 1);
118 }
119 */
120
121 void opt_successor(uint8_t* k, State *s, bool y, State* successor)
122 {
123
124 uint8_t Tt = 1 & opt_T(s);
125
126 successor->t = (s->t >> 1);
127 successor->t |= (Tt ^ (s->r >> 7 & 0x1) ^ (s->r >> 3 & 0x1)) << 15;
128
129 successor->b = s->b >> 1;
130 successor->b |= (opt_B(s) ^ (s->r & 0x1)) << 7;
131
132 successor->r = (k[opt__select(Tt,y,s->r)] ^ successor->b) + s->l ;
133 successor->l = successor->r+s->r;
134
135 }
136
137 void opt_suc(uint8_t* k,State* s, uint8_t *in)
138 {
139 State x2;
140 int i;
141 uint8_t head = 0;
142 for(i =0 ; i < 12 ; i++)
143 {
144 head = 1 & (in[i] >> 7);
145 opt_successor(k,s,head,&x2);
146
147 head = 1 & (in[i] >> 6);
148 opt_successor(k,&x2,head,s);
149
150 head = 1 & (in[i] >> 5);
151 opt_successor(k,s,head,&x2);
152
153 head = 1 & (in[i] >> 4);
154 opt_successor(k,&x2,head,s);
155
156 head = 1 & (in[i] >> 3);
157 opt_successor(k,s,head,&x2);
158
159 head = 1 & (in[i] >> 2);
160 opt_successor(k,&x2,head,s);
161
162 head = 1 & (in[i] >> 1);
163 opt_successor(k,s,head,&x2);
164
165 head = 1 & in[i];
166 opt_successor(k,&x2,head,s);
167
168 }
169
170 }
171
172 void opt_output(uint8_t* k,State* s, uint8_t *buffer)
173 {
174 uint8_t times = 0;
175 uint8_t bout = 0;
176 State temp = {0,0,0,0};
177 for( ; times < 4 ; times++)
178 {
179 bout =0;
180 bout |= (s->r & 0x4) << 5;
181 opt_successor(k,s,0,&temp);
182 bout |= (temp.r & 0x4) << 4;
183 opt_successor(k,&temp,0,s);
184 bout |= (s->r & 0x4) << 3;
185 opt_successor(k,s,0,&temp);
186 bout |= (temp.r & 0x4) << 2;
187 opt_successor(k,&temp,0,s);
188 bout |= (s->r & 0x4) << 1;
189 opt_successor(k,s,0,&temp);
190 bout |= (temp.r & 0x4) ;
191 opt_successor(k,&temp,0,s);
192 bout |= (s->r & 0x4) >> 1;
193 opt_successor(k,s,0,&temp);
194 bout |= (temp.r & 0x4) >> 2;
195 opt_successor(k,&temp,0,s);
196 buffer[times] = bout;
197 }
198
199 }
200
201 void opt_MAC(uint8_t* k, uint8_t* input, uint8_t* out)
202 {
203 State _init = {
204 ((k[0] ^ 0x4c) + 0xEC) & 0xFF,// l
205 ((k[0] ^ 0x4c) + 0x21) & 0xFF,// r
206 0x4c, // b
207 0xE012 // t
208 };
209
210 opt_suc(k,&_init,input);
211 //printf("\noutp ");
212 opt_output(k,&_init, out);
213 }
214 uint8_t rev_byte(uint8_t b) {
215 b = (b & 0xF0) >> 4 | (b & 0x0F) << 4;
216 b = (b & 0xCC) >> 2 | (b & 0x33) << 2;
217 b = (b & 0xAA) >> 1 | (b & 0x55) << 1;
218 return b;
219 }
220 void opt_reverse_arraybytecpy(uint8_t* dest, uint8_t *src, size_t len)
221 {
222 uint8_t i;
223 for( i =0; i< len ; i++)
224 dest[i] = rev_byte(src[i]);
225 }
226
227 void opt_doMAC(uint8_t *cc_nr_p, uint8_t *div_key_p, uint8_t mac[4])
228 {
229 static uint8_t cc_nr[13];
230 static uint8_t div_key[8];
231
232 opt_reverse_arraybytecpy(cc_nr, cc_nr_p,12);
233 memcpy(div_key,div_key_p,8);
234 uint8_t dest []= {0,0,0,0,0,0,0,0};
235 opt_MAC(div_key,cc_nr, dest);
236 //The output MAC must also be reversed
237 opt_reverse_arraybytecpy(mac, dest,12);
238 return;
239 }
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