git.zerfleddert.de Git - proxmark3-svn/blob - client/nonce2key/crypto1.c

   1 /*  crypto1.c
   2
   3         This program is free software; you can redistribute it and/or
   4         modify it under the terms of the GNU General Public License
   5         as published by the Free Software Foundation; either version 2
   6         of the License, or (at your option) any later version.
   7
   8         This program is distributed in the hope that it will be useful,
   9         but WITHOUT ANY WARRANTY; without even the implied warranty of
  10         MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11         GNU General Public License for more details.
  12
  13         You should have received a copy of the GNU General Public License
  14         along with this program; if not, write to the Free Software
  15         Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  16         MA  02110-1301, US
  17
  18         Copyright (C) 2008-2008 bla <blapost@gmail.com>
  19 */
  20 #include "crapto1.h"
  21 #include <stdlib.h>
  22
  23 #define SWAPENDIAN(x)\
  24         (x = (x >> 8 & 0xff00ff) | (x & 0xff00ff) << 8, x = x >> 16 | x << 16)
  25
  26 struct Crypto1State * crypto1_create(uint64_t key)
  27 {
  28         struct Crypto1State *s = malloc(sizeof(*s));
  29         int i;
  30
  31         for(i = 47;s && i > 0; i -= 2) {
  32                 s->odd  = s->odd  << 1 | BIT(key, (i - 1) ^ 7);
  33                 s->even = s->even << 1 | BIT(key, i ^ 7);
  34         }
  35         return s;
  36 }
  37 void crypto1_destroy(struct Crypto1State *state)
  38 {
  39         free(state);
  40 }
  41
  42 void crypto1_get_lfsr(struct Crypto1State *state, uint64_t *lfsr)
  43 {
  44         int i;
  45         for(*lfsr = 0, i = 23; i >= 0; --i) {
  46                 *lfsr = *lfsr << 1 | BIT(state->odd, i ^ 3);
  47                 *lfsr = *lfsr << 1 | BIT(state->even, i ^ 3);
  48         }
  49 }
  50 uint8_t crypto1_bit(struct Crypto1State *s, uint8_t in, int is_encrypted)
  51 {
  52         uint32_t feedin;
  53         uint32_t tmp;
  54         uint8_t ret = filter(s->odd);
  55
  56         feedin  = ret & !!is_encrypted;
  57         feedin ^= !!in;
  58         feedin ^= LF_POLY_ODD & s->odd;
  59         feedin ^= LF_POLY_EVEN & s->even;
  60         s->even = s->even << 1 | parity(feedin);
  61
  62         tmp = s->odd;
  63         s->odd = s->even;
  64         s->even = tmp;
  65
  66         return ret;
  67 }
  68 uint8_t crypto1_byte(struct Crypto1State *s, uint8_t in, int is_encrypted)
  69 {
  70 /*
  71         uint8_t i, ret = 0;
  72
  73         for (i = 0; i < 8; ++i)
  74                 ret |= crypto1_bit(s, BIT(in, i), is_encrypted) << i;
  75 */
  76         // unfold loop 20160112
  77         uint8_t ret = 0;
  78         ret |= crypto1_bit(s, BIT(in, 0), is_encrypted) << 0;
  79         ret |= crypto1_bit(s, BIT(in, 1), is_encrypted) << 1;
  80         ret |= crypto1_bit(s, BIT(in, 2), is_encrypted) << 2;
  81         ret |= crypto1_bit(s, BIT(in, 3), is_encrypted) << 3;
  82         ret |= crypto1_bit(s, BIT(in, 4), is_encrypted) << 4;
  83         ret |= crypto1_bit(s, BIT(in, 5), is_encrypted) << 5;
  84         ret |= crypto1_bit(s, BIT(in, 6), is_encrypted) << 6;
  85         ret |= crypto1_bit(s, BIT(in, 7), is_encrypted) << 7;
  86         return ret;
  87 }
  88 uint32_t crypto1_word(struct Crypto1State *s, uint32_t in, int is_encrypted)
  89 {
  90         uint32_t i, ret = 0;
  91
  92         for (i = 0; i < 4; ++i, in <<= 8)
  93                 ret = ret << 8 | crypto1_byte(s, in >> 24, is_encrypted);
  94
  95         return ret;
  96 }
  97
  98 /* prng_successor
  99  * helper used to obscure the keystream during authentication
 100  */
 101 uint32_t prng_successor(uint32_t x, uint32_t n)
 102 {
 103         SWAPENDIAN(x);
 104         while(n--)
 105                 x = x >> 1 | (x >> 16 ^ x >> 18 ^ x >> 19 ^ x >> 21) << 31;
 106
 107         return SWAPENDIAN(x);
 108 }