--- /dev/null
+/*****************************************************************************
+ * 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 <http://www.gnu.org/licenses/>.
+ ****************************************************************************/
+/**
+From "Dismantling iclass":
+ This section describes in detail the built-in key diversification algorithm of iClass.
+ Besides the obvious purpose of deriving a card key from a master key, this
+ algorithm intends to circumvent weaknesses in the cipher by preventing the
+ usage of certain ‘weak’ keys. In order to compute a diversified key, the iClass
+ reader first encrypts the card identity id with the master key K, using single
+ DES. The resulting ciphertext is then input to a function called hash0 which
+ outputs the diversified key k.
+
+ k = hash0(DES enc (id, K))
+
+ Here the DES encryption of id with master key K outputs a cryptogram c
+ of 64 bits. These 64 bits are divided as c = x, y, z [0] , . . . , z [7] ∈ F 82 × F 82 × (F 62 ) 8
+ which is used as input to the hash0 function. This function introduces some
+ obfuscation by performing a number of permutations, complement and modulo
+ operations, see Figure 2.5. Besides that, it checks for and removes patterns like
+ similar key bytes, which could produce a strong bias in the cipher. Finally, the
+ output of hash0 is the diversified card key k = k [0] , . . . , k [7] ∈ (F 82 ) 8 .
+
+
+**/
+
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <string.h>
+#include "cipherutils.h"
+#include "cipher.h"
+#include "../util.h"
+#include <stdio.h>
+#include "des.h"
+#include <inttypes.h>
+
+uint8_t pi[35] = {0x0F,0x17,0x1B,0x1D,0x1E,0x27,0x2B,0x2D,0x2E,0x33,0x35,0x39,0x36,0x3A,0x3C,0x47,0x4B,0x4D,0x4E,0x53,0x55,0x56,0x59,0x5A,0x5C,0x63,0x65,0x66,0x69,0x6A,0x6C,0x71,0x72,0x74,0x78};
+
+static des_context ctx_enc = {DES_ENCRYPT,{0}};
+static des_context ctx_dec = {DES_DECRYPT,{0}};
+
+static bool debug_print = false;
+
+/**
+ * @brief The key diversification algorithm uses 6-bit bytes.
+ * This implementation uses 64 bit uint to pack seven of them into one
+ * variable. When they are there, they are placed as follows:
+ * XXXX XXXX N0 .... N7, occupying the lsat 48 bits.
+ *
+ * This function picks out one from such a collection
+ * @param all
+ * @param n bitnumber
+ * @return
+ */
+uint8_t getSixBitByte(uint64_t c, int n)
+{
+ return (c >> (42-6*n)) & 0x3F;
+ //return (c >> n*6) & 0x3f;
+}
+
+/**
+ * @brief Puts back a six-bit 'byte' into a uint64_t.
+ * @param c buffer
+ * @param z the value to place there
+ * @param n bitnumber.
+ */
+void pushbackSixBitByte(uint64_t *c, uint8_t z, int n)
+{
+ //0x XXXX YYYY ZZZZ ZZZZ ZZZZ
+ // ^z0 ^z7
+ //z0: 1111 1100 0000 0000
+
+ uint64_t masked = z & 0x3F;
+ uint64_t eraser = 0x3F;
+ masked <<= 42-6*n;
+ eraser <<= 42-6*n;
+
+ //masked <<= 6*n;
+ //eraser <<= 6*n;
+
+ eraser = ~eraser;
+ (*c) &= eraser;
+ (*c) |= masked;
+
+}
+
+uint64_t swapZvalues(uint64_t c)
+{
+ uint64_t newz = 0;
+ pushbackSixBitByte(&newz, getSixBitByte(c,0),7);
+ pushbackSixBitByte(&newz, getSixBitByte(c,1),6);
+ pushbackSixBitByte(&newz, getSixBitByte(c,2),5);
+ pushbackSixBitByte(&newz, getSixBitByte(c,3),4);
+ pushbackSixBitByte(&newz, getSixBitByte(c,4),3);
+ pushbackSixBitByte(&newz, getSixBitByte(c,5),2);
+ pushbackSixBitByte(&newz, getSixBitByte(c,6),1);
+ pushbackSixBitByte(&newz, getSixBitByte(c,7),0);
+ newz |= (c & 0xFFFF000000000000);
+ return newz;
+}
+
+/**
+* @return 4 six-bit bytes chunked into a uint64_t,as 00..00a0a1a2a3
+*/
+uint64_t ck(int i, int j, uint64_t z)
+{
+
+// printf("ck( i=%d, j=%d), zi=[%d],zj=[%d] \n",i,j,getSixBitByte(z,i),getSixBitByte(z,j) );
+
+ if(i == 1 && j == -1)
+ {
+ // ck(1, −1, z [0] . . . z [3] ) = z [0] . . . z [3]
+ return z;
+
+ }else if( j == -1)
+ {
+ // ck(i, −1, z [0] . . . z [3] ) = ck(i − 1, i − 2, z [0] . . . z [3] )
+ return ck(i-1,i-2, z);
+ }
+
+ if(getSixBitByte(z,i) == getSixBitByte(z,j))
+ {
+ // TODO, I dont know what they mean here in the paper
+ //ck(i, j − 1, z [0] . . . z [i] ← j . . . z [3] )
+ uint64_t newz = 0;
+ int c;
+ //printf("z[i]=z[i] (0x%02x), i=%d, j=%d\n",getSixBitByte(z,i),i,j );
+ for(c = 0; c < 4 ;c++)
+ {
+ uint8_t val = getSixBitByte(z,c);
+ if(c == i)
+ {
+ //printf("oops\n");
+ pushbackSixBitByte(&newz, j, c);
+ }else
+ {
+ pushbackSixBitByte(&newz, val, c);
+ }
+ }
+ return ck(i,j-1,newz);
+ }else
+ {
+ return ck(i,j-1,z);
+ }
+
+}
+/**
+
+ Definition 8.
+ Let the function check : (F 62 ) 8 → (F 62 ) 8 be defined as
+ check(z [0] . . . z [7] ) = ck(3, 2, z [0] . . . z [3] ) · ck(3, 2, z [4] . . . z [7] )
+
+ where ck : N × N × (F 62 ) 4 → (F 62 ) 4 is defined as
+
+ ck(1, −1, z [0] . . . z [3] ) = z [0] . . . z [3]
+ ck(i, −1, z [0] . . . z [3] ) = ck(i − 1, i − 2, z [0] . . . z [3] )
+ ck(i, j, z [0] . . . z [3] ) =
+ ck(i, j − 1, z [0] . . . z [i] ← j . . . z [3] ), if z [i] = z [j] ;
+ ck(i, j − 1, z [0] . . . z [3] ), otherwise
+
+ otherwise.
+**/
+
+uint64_t check(uint64_t z)
+{
+ //These 64 bits are divided as c = x, y, z [0] , . . . , z [7]
+
+ // ck(3, 2, z [0] . . . z [3] )
+ uint64_t ck1 = ck(3,2, z );
+
+ // ck(3, 2, z [4] . . . z [7] )
+ uint64_t ck2 = ck(3,2, z << 24);
+ ck1 &= 0x00000000FFFFFF000000;
+ ck2 &= 0x00000000FFFFFF000000;
+
+ return ck1 | ck2 >> 24;
+
+}
+
+void permute(BitstreamIn *p_in, uint64_t z,int l,int r, BitstreamOut* out)
+{
+ if(bitsLeft(p_in) == 0)
+ {
+ return;
+ }
+ bool pn = tailBit(p_in);
+ if( pn ) // pn = 1
+ {
+ uint8_t zl = getSixBitByte(z,l);
+ //printf("permute pushing, zl=0x%02x, zl+1=0x%02x\n", zl, zl+1);
+ push6bits(out, zl+1);
+ permute(p_in, z, l+1,r, out);
+ }else // otherwise
+ {
+ uint8_t zr = getSixBitByte(z,r);
+ //printf("permute pushing, zr=0x%02x\n", zr);
+ push6bits(out, zr);
+ permute(p_in,z,l,r+1,out);
+ }
+}
+void testPermute()
+{
+
+ uint64_t x = 0;
+ pushbackSixBitByte(&x,0x00,0);
+ pushbackSixBitByte(&x,0x01,1);
+ pushbackSixBitByte(&x,0x02,2);
+ pushbackSixBitByte(&x,0x03,3);
+ pushbackSixBitByte(&x,0x04,4);
+ pushbackSixBitByte(&x,0x05,5);
+ pushbackSixBitByte(&x,0x06,6);
+ pushbackSixBitByte(&x,0x07,7);
+
+ uint8_t mres[8] = { getSixBitByte(x, 0),
+ getSixBitByte(x, 1),
+ getSixBitByte(x, 2),
+ getSixBitByte(x, 3),
+ getSixBitByte(x, 4),
+ getSixBitByte(x, 5),
+ getSixBitByte(x, 6),
+ getSixBitByte(x, 7)};
+ printarr("input_perm", mres,8);
+
+ uint8_t p = ~pi[0];
+ BitstreamIn p_in = { &p, 8,0 };
+ uint8_t outbuffer[] = {0,0,0,0,0,0,0,0};
+ BitstreamOut out = {outbuffer,0,0};
+
+ permute(&p_in, x,0,4, &out);
+
+ uint64_t permuted = bytes_to_num(outbuffer,8);
+ //printf("zTilde 0x%"PRIX64"\n", zTilde);
+ permuted >>= 16;
+
+ uint8_t res[8] = { getSixBitByte(permuted, 0),
+ getSixBitByte(permuted, 1),
+ getSixBitByte(permuted, 2),
+ getSixBitByte(permuted, 3),
+ getSixBitByte(permuted, 4),
+ getSixBitByte(permuted, 5),
+ getSixBitByte(permuted, 6),
+ getSixBitByte(permuted, 7)};
+ printarr("permuted", res, 8);
+}
+void printbegin()
+{
+ if(! debug_print)
+ return;
+
+ printf(" | x| y|z0|z1|z2|z3|z4|z5|z6|z7|\n");
+}
+
+void printState(char* desc, int x,int y, uint64_t c)
+{
+ if(! debug_print)
+ return;
+
+ printf("%s : ", desc);
+ //uint8_t x = (c & 0xFF00000000000000 ) >> 56;
+ //uint8_t y = (c & 0x00FF000000000000 ) >> 48;
+ printf(" %02x %02x", x,y);
+ int i ;
+ for(i =0 ; i < 8 ; i++)
+ {
+ printf(" %02x", getSixBitByte(c,i));
+ }
+ printf("\n");
+}
+
+/**
+ * @brief
+ *Definition 11. Let the function hash0 : F 82 × F 82 × (F 62 ) 8 → (F 82 ) 8 be defined as
+ * hash0(x, y, z [0] . . . z [7] ) = k [0] . . . k [7] where
+ * z'[i] = (z[i] mod (63-i)) + i i = 0...3
+ * z'[i+4] = (z[i+4] mod (64-i)) + i i = 0...3
+ * ẑ = check(z');
+ * @param c
+ * @param k this is where the diversified key is put (should be 8 bytes)
+ * @return
+ */
+void hash0(uint64_t c, uint8_t *k)
+{
+ printbegin();
+ //These 64 bits are divided as c = x, y, z [0] , . . . , z [7]
+ // x = 8 bits
+ // y = 8 bits
+ // z0-z7 6 bits each : 48 bits
+ uint8_t x = (c & 0xFF00000000000000 ) >> 56;
+ uint8_t y = (c & 0x00FF000000000000 ) >> 48;
+ printState("origin",x,y,c);
+ int n;
+ uint8_t zn, zn4, _zn, _zn4;
+ uint64_t zP = 0;
+
+ for(n = 0; n < 4 ; n++)
+ {
+ zn = getSixBitByte(c,n);
+ zn4 = getSixBitByte(c,n+4);
+
+ _zn = (zn % (63-n)) + n;
+ _zn4 = (zn4 % (64-n)) + n;
+
+ pushbackSixBitByte(&zP, _zn,n);
+ pushbackSixBitByte(&zP, _zn4,n+4);
+
+ }
+ printState("x|y|z'",x,y,zP);
+
+ uint64_t zCaret = check(zP);
+ printState("x|y|z^",x,y,zP);
+
+
+ uint8_t p = pi[x % 35];
+
+ if(x & 1) //Check if x7 is 1
+ {
+ p = ~p;
+ }
+ printState("p|y|z^",p,y,zP);
+ //if(debug_print) printf("p:%02x\n", p);
+
+ BitstreamIn p_in = { &p, 8,0 };
+ uint8_t outbuffer[] = {0,0,0,0,0,0,0,0};
+ BitstreamOut out = {outbuffer,0,0};
+ permute(&p_in,zCaret,0,4,&out);//returns 48 bits? or 6 8-bytes
+
+ //Out is now a buffer containing six-bit bytes, should be 48 bits
+ // if all went well
+ //printf("Permute output is %d num bits (48?)\n", out.numbits);
+ //Shift z-values down onto the lower segment
+
+ uint64_t zTilde = bytes_to_num(outbuffer,8);
+
+ //printf("zTilde 0x%"PRIX64"\n", zTilde);
+ zTilde >>= 16;
+ //printf("z~ 0x%"PRIX64"\n", zTilde);
+ printState("p|y|z~", p,y,zTilde);
+
+ int i;
+ int zerocounter =0 ;
+ for(i =0 ; i < 8 ; i++)
+ {
+
+ // the key on index i is first a bit from y
+ // then six bits from z,
+ // then a bit from p
+
+ // Init with zeroes
+ k[i] = 0;
+ // First, place yi leftmost in k
+ //k[i] |= (y << i) & 0x80 ;
+
+ // First, place y(7-i) leftmost in k
+ k[i] |= (y << (7-i)) & 0x80 ;
+
+ //printf("y%d = %d\n",i,(y << i) & 0x80);
+
+ uint8_t zTilde_i = getSixBitByte(zTilde, i);
+ //printf("zTilde_%d 0x%02x (should be <= 0x3F)\n",i, zTilde_i);
+ // zTildeI is now on the form 00XXXXXX
+ // with one leftshift, it'll be
+ // 0XXXXXX0
+ // So after leftshift, we can OR it into k
+ // However, when doing complement, we need to
+ // again MASK 0XXXXXX0 (0x7E)
+ zTilde_i <<= 1;
+
+ //Finally, add bit from p or p-mod
+ //Shift bit i into rightmost location (mask only after complement)
+ uint8_t p_i = p >> i & 0x1;
+
+ if( k[i] )// yi = 1
+ {
+ //printf("k[%d] +1\n", i);
+ k[i] |= ~zTilde_i & 0x7E;
+ k[i] |= p_i & 1;
+ k[i] += 1;
+
+ }else // otherwise
+ {
+ k[i] |= zTilde_i & 0x7E;
+ k[i] |= (~p_i) & 1;
+ }
+ if((k[i] & 1 )== 0)
+ {
+ zerocounter ++;
+ }
+ }
+ //printf("zerocounter=%d (should be 4)\n",zerocounter);
+ //printf("permute fin, y:0x%02x, x: 0x%02x\n", y, x);
+
+ //return k;
+}
+
+void reorder(uint8_t arr[8])
+{
+ uint8_t tmp[4] = {arr[3],arr[2],arr[1], arr[0]};
+ arr[0] = arr[7];
+ arr[1] = arr[6];
+ arr[2] = arr[5];
+ arr[3] = arr[4];
+ arr[4] = tmp[0];//arr[3];
+ arr[5] = tmp[1];//arr[2];
+ arr[6] = tmp[2];//arr[3];
+ arr[7] = tmp[3];//arr[1]
+}
+
+//extern void printarr(char * name, uint8_t* arr, int len);
+
+bool des_getParityBitFromKey(uint8_t key)
+{//The top 7 bits is used
+ bool parity = ((key & 0x80) >> 7)
+ ^ ((key & 0x40) >> 6) ^ ((key & 0x20) >> 5)
+ ^ ((key & 0x10) >> 4) ^ ((key & 0x08) >> 3)
+ ^ ((key & 0x04) >> 2) ^ ((key & 0x02) >> 1);
+ return !parity;
+}
+void des_checkParity(uint8_t* key)
+{
+ int i;
+ int fails =0;
+ for(i =0 ; i < 8 ; i++)
+ {
+ bool parity = des_getParityBitFromKey(key[i]);
+ if(parity != (key[i] & 0x1))
+ {
+ fails++;
+ printf("parity1 fail, byte %d [%02x] was %d, should be %d\n",i,key[i],(key[i] & 0x1),parity);
+ }
+ }
+ if(fails)
+ {
+ printf("parity fails: %d\n", fails);
+ }else
+ {
+ printf("Key syntax is with parity bits inside each byte\n");
+ }
+}
+
+void printarr2(char * name, uint8_t* arr, int len)
+{
+ int i ;
+ printf("%s :", name);
+ for(i =0 ; i< len ; i++)
+ {
+ printf("%02x",*(arr+i));
+ }
+ printf("\n");
+}
projects / proxmark3-svn / blobdiff