X-Git-Url: http://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/6c0f60ca7bcd7737b5d3867004f1cbdc9532720c..3ad48540d4d77f50cc62d16acb78f17019ef431d:/client/loclass/cipher.c diff --git a/client/loclass/cipher.c b/client/loclass/cipher.c new file mode 100644 index 00000000..aefb5df5 --- /dev/null +++ b/client/loclass/cipher.c @@ -0,0 +1,250 @@ +/***************************************************************************** + * This file is part of iClassCipher. 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 IClassCipher. If not, see . + ****************************************************************************/ + +#include "cipher.h" +#include "cipherutils.h" +#include +#include +#include +#include +#include +#include +#include "fileutils.h" +uint8_t keytable[] = { 0,0,0,0,0,0,0,0}; + +/** +* 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[12],uint8_t div_key[8], uint8_t mac[4]) +{ + // Reversed "on-the-wire" data + uint8_t cc_nr_r[12] = {0}; + reverse_arraycopy(cc_nr, cc_nr_r,12); + BitstreamIn bitstream = {cc_nr_r,12 * 8,0}; + uint8_t dest [8]= {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); + return; +} + +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; +}