git.zerfleddert.de Git - proxmark3-svn/blob - common/crapto1/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 #if defined(__arm__)
  27 void crypto1_create(struct Crypto1State *s, uint64_t key)
  28 {
  29 #else
  30 struct Crypto1State * crypto1_create(uint64_t key)
  31 {
  32         struct Crypto1State *s = malloc(sizeof(*s));
  33 #endif
  34         int i;
  35
  36         for(i = 47;s && i > 0; i -= 2) {
  37                 s->odd  = s->odd  << 1 | BIT(key, (i - 1) ^ 7);
  38                 s->even = s->even << 1 | BIT(key, i ^ 7);
  39         }
  40 #if defined(__arm__)
  41         return;
  42 #else
  43         return s;
  44 #endif
  45 }
  46 #if defined(__arm__)
  47 void crypto1_destroy(struct Crypto1State *state)
  48 {
  49         state->odd = 0;
  50         state->even = 0;
  51 }
  52 #else
  53 void crypto1_destroy(struct Crypto1State *state)
  54 {
  55         free(state);
  56 }
  57 #endif
  58 void crypto1_get_lfsr(struct Crypto1State *state, uint64_t *lfsr)
  59 {
  60         int i;
  61         for(*lfsr = 0, i = 23; i >= 0; --i) {
  62                 *lfsr = *lfsr << 1 | BIT(state->odd, i ^ 3);
  63                 *lfsr = *lfsr << 1 | BIT(state->even, i ^ 3);
  64         }
  65 }
  66 uint8_t crypto1_bit(struct Crypto1State *s, uint8_t in, int is_encrypted)
  67 {
  68         uint32_t feedin;
  69         uint32_t tmp;
  70         uint8_t ret = filter(s->odd);
  71
  72         feedin  = ret & !!is_encrypted;
  73         feedin ^= !!in;
  74         feedin ^= LF_POLY_ODD & s->odd;
  75         feedin ^= LF_POLY_EVEN & s->even;
  76         s->even = s->even << 1 | parity(feedin);
  77
  78         tmp = s->odd;
  79         s->odd = s->even;
  80         s->even = tmp;
  81
  82         return ret;
  83 }
  84 uint8_t crypto1_byte(struct Crypto1State *s, uint8_t in, int is_encrypted)
  85 {
  86         uint8_t i, ret = 0;
  87
  88         for (i = 0; i < 8; ++i)
  89                 ret |= crypto1_bit(s, BIT(in, i), is_encrypted) << i;
  90
  91         return ret;
  92 }
  93 uint32_t crypto1_word(struct Crypto1State *s, uint32_t in, int is_encrypted)
  94 {
  95         uint32_t i, ret = 0;
  96
  97         for (i = 0; i < 4; ++i, in <<= 8)
  98                 ret = ret << 8 | crypto1_byte(s, in >> 24, is_encrypted);
  99
 100         return ret;
 101 }
 102
 103 /* prng_successor
 104  * helper used to obscure the keystream during authentication
 105  */
 106 uint32_t prng_successor(uint32_t x, uint32_t n)
 107 {
 108         SWAPENDIAN(x);
 109         while(n--)
 110                 x = x >> 1 | (x >> 16 ^ x >> 18 ^ x >> 19 ^ x >> 21) << 31;
 111
 112         return SWAPENDIAN(x);
 113 }