--- /dev/null
+/*****************************************************************************
+ * 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/>.
+ *
+ *
+ *
+ ****************************************************************************/
+
+/**
+
+ This file contains an optimized version of the MAC-calculation algorithm. Some measurements on
+ a std laptop showed it runs in about 1/3 of the time:
+
+ Std: 0.428962
+ Opt: 0.151609
+
+ Additionally, it is self-reliant, not requiring e.g. bitstreams from the cipherutils, thus can
+ be easily dropped into a code base.
+
+ The optimizations have been performed in the following steps:
+ * Parameters passed by reference instead of by value.
+ * Iteration instead of recursion, un-nesting recursive loops into for-loops.
+ * Handling of bytes instead of individual bits, for less shuffling and masking
+ * Less creation of "objects", structs, and instead reuse of alloc:ed memory
+ * Inlining some functions via #define:s
+
+ As a consequence, this implementation is less generic. Also, I haven't bothered documenting this.
+ For a thorough documentation, check out the MAC-calculation within cipher.c instead.
+
+ -- MHS 2015
+**/
+
+#include "optimized_cipher.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <time.h>
+
+/**
+* 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;
+
+
+#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))
+
+#define opt_B(s) (((s->b >> 6) ^ (s->b >> 5) ^ (s->b >> 4) ^ (s->b)) & 0x1)
+
+#define opt__select(x,y,r) (4 & (((r & (r << 2)) >> 5) ^ ((r & ~(r << 2)) >> 4) ^ ( (r | r << 2) >> 3)))\
+ |(2 & (((r | r << 2) >> 6) ^ ( (r | r << 2) >> 1) ^ (r >> 5) ^ r ^ ((x^y) << 1)))\
+ |(1 & (((r & ~(r << 2)) >> 4) ^ ((r & (r << 2)) >> 3) ^ r ^ x))
+
+/*
+ * Some background on the expression above can be found here...
+uint8_t xopt__select(bool x, bool y, uint8_t r)
+{
+ uint8_t r_ls2 = r << 2;
+ uint8_t r_and_ls2 = r & r_ls2;
+ uint8_t r_or_ls2 = r | r_ls2;
+
+ //r: r0 r1 r2 r3 r4 r5 r6 r7
+ //r_ls2: r2 r3 r4 r5 r6 r7 0 0
+ // z0
+ // z1
+
+// uint8_t z0 = (r0 & r2) ^ (r1 & ~r3) ^ (r2 | r4); // <-- original
+ uint8_t z0 = (r_and_ls2 >> 5) ^ ((r & ~r_ls2) >> 4) ^ ( r_or_ls2 >> 3);
+
+// uint8_t z1 = (r0 | r2) ^ ( r5 | r7) ^ r1 ^ r6 ^ x ^ y; // <-- original
+ uint8_t z1 = (r_or_ls2 >> 6) ^ ( r_or_ls2 >> 1) ^ (r >> 5) ^ r ^ ((x^y) << 1);
+
+// uint8_t z2 = (r3 & ~r5) ^ (r4 & r6 ) ^ r7 ^ x; // <-- original
+ uint8_t z2 = ((r & ~r_ls2) >> 4) ^ (r_and_ls2 >> 3) ^ r ^ x;
+
+ return (z0 & 4) | (z1 & 2) | (z2 & 1);
+}
+*/
+
+void opt_successor(uint8_t* k, State *s, bool y, State* successor)
+{
+
+ uint8_t Tt = 1 & opt_T(s);
+
+ successor->t = (s->t >> 1);
+ successor->t |= (Tt ^ (s->r >> 7 & 0x1) ^ (s->r >> 3 & 0x1)) << 15;
+
+ successor->b = s->b >> 1;
+ successor->b |= (opt_B(s) ^ (s->r & 0x1)) << 7;
+
+ successor->r = (k[opt__select(Tt,y,s->r)] ^ successor->b) + s->l ;
+ successor->l = successor->r+s->r;
+
+}
+
+void opt_suc(uint8_t* k,State* s, uint8_t *in)
+{
+ State x2;
+ int i;
+ uint8_t head = 0;
+ for(i =0 ; i < 12 ; i++)
+ {
+ head = 1 & (in[i] >> 7);
+ opt_successor(k,s,head,&x2);
+
+ head = 1 & (in[i] >> 6);
+ opt_successor(k,&x2,head,s);
+
+ head = 1 & (in[i] >> 5);
+ opt_successor(k,s,head,&x2);
+
+ head = 1 & (in[i] >> 4);
+ opt_successor(k,&x2,head,s);
+
+ head = 1 & (in[i] >> 3);
+ opt_successor(k,s,head,&x2);
+
+ head = 1 & (in[i] >> 2);
+ opt_successor(k,&x2,head,s);
+
+ head = 1 & (in[i] >> 1);
+ opt_successor(k,s,head,&x2);
+
+ head = 1 & in[i];
+ opt_successor(k,&x2,head,s);
+
+ }
+
+}
+
+void opt_output(uint8_t* k,State* s, uint8_t *buffer)
+{
+ uint8_t times = 0;
+ uint8_t bout = 0;
+ State temp = {0,0,0,0};
+ for( ; times < 4 ; times++)
+ {
+ bout =0;
+ bout |= (s->r & 0x4) << 5;
+ opt_successor(k,s,0,&temp);
+ bout |= (temp.r & 0x4) << 4;
+ opt_successor(k,&temp,0,s);
+ bout |= (s->r & 0x4) << 3;
+ opt_successor(k,s,0,&temp);
+ bout |= (temp.r & 0x4) << 2;
+ opt_successor(k,&temp,0,s);
+ bout |= (s->r & 0x4) << 1;
+ opt_successor(k,s,0,&temp);
+ bout |= (temp.r & 0x4) ;
+ opt_successor(k,&temp,0,s);
+ bout |= (s->r & 0x4) >> 1;
+ opt_successor(k,s,0,&temp);
+ bout |= (temp.r & 0x4) >> 2;
+ opt_successor(k,&temp,0,s);
+ buffer[times] = bout;
+ }
+
+}
+
+void opt_MAC(uint8_t* k, uint8_t* input, uint8_t* out)
+{
+ State _init = {
+ ((k[0] ^ 0x4c) + 0xEC) & 0xFF,// l
+ ((k[0] ^ 0x4c) + 0x21) & 0xFF,// r
+ 0x4c, // b
+ 0xE012 // t
+ };
+
+ opt_suc(k,&_init,input);
+ //printf("\noutp ");
+ opt_output(k,&_init, out);
+}
+uint8_t rev_byte(uint8_t b) {
+ b = (b & 0xF0) >> 4 | (b & 0x0F) << 4;
+ b = (b & 0xCC) >> 2 | (b & 0x33) << 2;
+ b = (b & 0xAA) >> 1 | (b & 0x55) << 1;
+ return b;
+}
+void opt_reverse_arraybytecpy(uint8_t* dest, uint8_t *src, size_t len)
+{
+ uint8_t i;
+ for( i =0; i< len ; i++)
+ dest[i] = rev_byte(src[i]);
+}
+
+void opt_doMAC(uint8_t *cc_nr_p, uint8_t *div_key_p, uint8_t mac[4])
+{
+ static uint8_t cc_nr[13];
+ static uint8_t div_key[8];
+
+ opt_reverse_arraybytecpy(cc_nr, cc_nr_p,12);
+ memcpy(div_key,div_key_p,8);
+ uint8_t dest []= {0,0,0,0,0,0,0,0};
+ opt_MAC(div_key,cc_nr, dest);
+ //The output MAC must also be reversed
+ opt_reverse_arraybytecpy(mac, dest,12);
+ return;
+}
projects / proxmark3-svn / commitdiff