From 7847961b25c507b5a291c8ddb9aa1c1b222a4b11 Mon Sep 17 00:00:00 2001 From: "roel@libnfc.org" Date: Sun, 1 Jul 2012 07:38:26 +0000 Subject: [PATCH] added mfkey --- tools/mfkey/Makefile | 17 ++ tools/mfkey/crapto1.c | 478 ++++++++++++++++++++++++++++++++++ tools/mfkey/crapto1.h | 93 +++++++ tools/mfkey/crypto1.c | 93 +++++++ tools/mfkey/example_trace.txt | 15 ++ tools/mfkey/mfkey.c | 65 +++++ 6 files changed, 761 insertions(+) create mode 100755 tools/mfkey/Makefile create mode 100755 tools/mfkey/crapto1.c create mode 100755 tools/mfkey/crapto1.h create mode 100755 tools/mfkey/crypto1.c create mode 100644 tools/mfkey/example_trace.txt create mode 100755 tools/mfkey/mfkey.c diff --git a/tools/mfkey/Makefile b/tools/mfkey/Makefile new file mode 100755 index 00000000..e70ee48c --- /dev/null +++ b/tools/mfkey/Makefile @@ -0,0 +1,17 @@ +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) $(LIBS) diff --git a/tools/mfkey/crapto1.c b/tools/mfkey/crapto1.c new file mode 100755 index 00000000..9d491d12 --- /dev/null +++ b/tools/mfkey/crapto1.c @@ -0,0 +1,478 @@ +/* crapto1.c + + This program is free software; you can redistribute it and/or + modify it under the terms of the GNU General Public License + as published by the Free Software Foundation; either version 2 + of the License, or (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 51 Franklin Street, Fifth Floor, + Boston, MA 02110-1301, US$ + + Copyright (C) 2008-2008 bla +*/ +#include "crapto1.h" +#include + +#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; +} diff --git a/tools/mfkey/crapto1.h b/tools/mfkey/crapto1.h new file mode 100755 index 00000000..127a17d1 --- /dev/null +++ b/tools/mfkey/crapto1.h @@ -0,0 +1,93 @@ +/* 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 +*/ +#ifndef CRAPTO1_INCLUDED +#define CRAPTO1_INCLUDED +#include +#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 diff --git a/tools/mfkey/crypto1.c b/tools/mfkey/crypto1.c new file mode 100755 index 00000000..e2aab71b --- /dev/null +++ b/tools/mfkey/crypto1.c @@ -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 +*/ +#include "crapto1.h" +#include + +#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); +} diff --git a/tools/mfkey/example_trace.txt b/tools/mfkey/example_trace.txt new file mode 100644 index 00000000..16637fb5 --- /dev/null +++ b/tools/mfkey/example_trace.txt @@ -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 + diff --git a/tools/mfkey/mfkey.c b/tools/mfkey/mfkey.c new file mode 100755 index 00000000..442403f4 --- /dev/null +++ b/tools/mfkey/mfkey.c @@ -0,0 +1,65 @@ +// Test-file: test2.c +#include "crapto1.h" +#include + +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 <{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; +} -- 2.39.5