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proxmark3/common/crapto1/crapto1.c
iceman1001 3e5bd575f6 syntax sugar
2017-12-24 10:22:02 +01:00

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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) 2008-2014 bla <blapost@gmail.com>
*/
#include "crapto1.h"
#include <stdlib.h>
#include "parity.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
/** 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 | evenparity32(*item & mask1);
p = p << 1 | evenparity32(*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)) { // replace
*tbl |= filter(*tbl) ^ bit;
} else if(filter(*tbl) == bit) { // insert
*++*end = *++tbl;
*tbl = tbl[-1] | 1;
} else { // drop
*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, bucket_array_t bucket)
{
uint32_t *o, *e;
bucket_info_t bucket_info;
if(rem == -1) {
for(e = e_head; e <= e_tail; ++e) {
*e = *e << 1 ^ evenparity32(*e & LF_POLY_EVEN) ^ !!(in & 4);
for(o = o_head; o <= o_tail; ++o, ++sl) {
sl->even = *o;
sl->odd = *e ^ evenparity32(*o & LF_POLY_ODD);
sl[1].odd = sl[1].even = 0;
}
}
return sl;
}
for(uint32_t 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;
}
bucket_sort_intersect(e_head, e_tail, o_head, o_tail, &bucket_info, bucket);
for (int i = bucket_info.numbuckets - 1; i >= 0; i--) {
sl = recover(bucket_info.bucket_info[1][i].head, bucket_info.bucket_info[1][i].tail, oks,
bucket_info.bucket_info[0][i].head, bucket_info.bucket_info[0][i].tail, eks,
rem, sl, in, bucket);
}
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;
// split the keystream into an odd and even part
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;
// allocate memory for out of place bucket_sort
bucket_array_t bucket;
for (uint32_t i = 0; i < 2; i++) {
for (uint32_t j = 0; j <= 0xff; j++) {
bucket[i][j].head = malloc(sizeof(uint32_t) << 14);
if (!bucket[i][j].head) {
goto out;
}
}
}
// initialize statelists: add all possible states which would result into the rightmost 2 bits of the keystream
for(i = 1 << 20; i >= 0; --i) {
if(filter(i) == (oks & 1))
*++odd_tail = i;
if(filter(i) == (eks & 1))
*++even_tail = i;
}
// extend the statelists. Look at the next 8 Bits of the keystream (4 Bit each odd and even):
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);
}
// the statelists now contain all states which could have generated the last 10 Bits of the keystream.
// 22 bits to go to recover 32 bits in total. From now on, we need to take the "in"
// parameter into account.
in = (in >> 16 & 0xff) | (in << 16) | (in & 0xff00); // Byte swapping
recover(odd_head, odd_tail, oks, even_head, even_tail, eks, 11, statelist, in << 1, bucket);
out:
for (uint32_t i = 0; i < 2; i++)
for (uint32_t j = 0; j <= 0xff; j++)
free(bucket[i][j].head);
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 | evenparity32(i & S1[j]);
for(j = 0; j < 32; ++j)
hi[j] = evenparity32(i & T1[j]);
for(; tail >= table; --tail) {
for(j = 0; j < 3; ++j) {
*tail = *tail << 1;
*tail |= evenparity32((i & C1[j]) ^ (*tail & C2[j]));
if(filter(*tail) != oks[29 + j])
goto continue2;
}
for(j = 0; j < 19; ++j)
win = win << 1 | evenparity32(*tail & S2[j]);
win ^= low;
for(j = 0; j < 32; ++j) {
win = win << 1 ^ hi[j] ^ evenparity32(*tail & T2[j]);
if(filter(win) != eks[j])
goto continue2;
}
*tail = *tail << 1 | evenparity32(LF_POLY_EVEN & *tail);
sl->odd = *tail ^ evenparity32(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;
uint32_t t;
s->odd &= 0xffffff;
t = s->odd, s->odd = s->even, s->even = t;
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 |= evenparity32(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;
*/
// unfold loop 20160112
uint8_t ret = 0;
ret |= lfsr_rollback_bit(s, BIT(in, 7), fb) << 7;
ret |= lfsr_rollback_bit(s, BIT(in, 6), fb) << 6;
ret |= lfsr_rollback_bit(s, BIT(in, 5), fb) << 5;
ret |= lfsr_rollback_bit(s, BIT(in, 4), fb) << 4;
ret |= lfsr_rollback_bit(s, BIT(in, 3), fb) << 3;
ret |= lfsr_rollback_bit(s, BIT(in, 2), fb) << 2;
ret |= lfsr_rollback_bit(s, BIT(in, 1), fb) << 1;
ret |= lfsr_rollback_bit(s, BIT(in, 0), fb) << 0;
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);
*/
// unfold loop 20160112
uint32_t ret = 0;
ret |= lfsr_rollback_bit(s, BEBIT(in, 31), fb) << (31 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 30), fb) << (30 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 29), fb) << (29 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 28), fb) << (28 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 27), fb) << (27 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 26), fb) << (26 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 25), fb) << (25 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 24), fb) << (24 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 23), fb) << (23 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 22), fb) << (22 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 21), fb) << (21 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 20), fb) << (20 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 19), fb) << (19 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 18), fb) << (18 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 17), fb) << (17 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 16), fb) << (16 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 15), fb) << (15 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 14), fb) << (14 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 13), fb) << (13 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 12), fb) << (12 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 11), fb) << (11 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 10), fb) << (10 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 9), fb) << (9 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 8), fb) << (8 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 7), fb) << (7 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 6), fb) << (6 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 5), fb) << (5 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 4), fb) << (4 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 3), fb) << (3 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 2), fb) << (2 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 1), fb) << (1 ^ 24);
ret |= lfsr_rollback_bit(s, BEBIT(in, 0), fb) << (0 ^ 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;
}
/** validate_prng_nonce
* Determine if nonce is deterministic. ie: Suspectable to Darkside attack.
* returns
* true = weak prng
* false = hardend prng
*/
bool validate_prng_nonce(uint32_t nonce) {
// init prng table:
nonce_distance(nonce, nonce);
return ((65535 - dist[nonce >> 16] + dist[nonce & 0xffff]) % 65535) == 16;
}
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 *candidates = malloc(4 << 10);
if (!candidates) return 0;
uint32_t c, entry;
int size = 0, i, good;
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 no_par)
{
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);
if (no_par)
break;
nr = ks1 ^ (prefix | c << 5);
rr = ks2 ^ rresp;
good &= evenparity32(nr & 0x000000ff) ^ parities[c][3] ^ BIT(ks2, 24);
good &= evenparity32(rr & 0xff000000) ^ parities[c][4] ^ BIT(ks2, 16);
good &= evenparity32(rr & 0x00ff0000) ^ parities[c][5] ^ BIT(ks2, 8);
good &= evenparity32(rr & 0x0000ff00) ^ parities[c][6] ^ BIT(ks2, 0);
good &= evenparity32(rr & 0x000000ff) ^ parities[c][7] ^ ks3;
}
return sl + good;
}
/** lfsr_common_prefix
* Implentation of the common prefix attack.
* Requires the 28 bit constant prefix used as reader nonce (pfx)
* The reader response used (rr)
* The keystream used to encrypt the observed NACK's (ks)
* The parity bits (par)
* It returns a zero terminated list of possible cipher states after the
* tag nonce was fed in
*/
struct Crypto1State* lfsr_common_prefix(uint32_t pfx, uint32_t rr, uint8_t ks[8], uint8_t par[8][8], uint32_t no_par)
{
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) << 24); // was << 20. Need more for no_par special attack. Enough???
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, no_par);
}
s->odd = s->even = 0;
out:
free(odd);
free(even);
return statelist;
}
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