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
  22 #include <stdlib.h>
  23 #include "parity.h"
  24
  25 #define SWAPENDIAN(x)\
  26         (x = (x >> 8 & 0xff00ff) | (x & 0xff00ff) << 8, x = x >> 16 | x << 16)
  27
  28 #if defined(__arm__) && !defined(__linux__) && !defined(_WIN32) && !defined(__APPLE__)          // bare metal ARM Proxmark lacks malloc()/free()
  29 void crypto1_create(struct Crypto1State *s, uint64_t key)
  30 {
  31         int i;
  32
  33         for(i = 47;s && i > 0; i -= 2) {
  34                 s->odd  = s->odd  << 1 | BIT(key, (i - 1) ^ 7);
  35                 s->even = s->even << 1 | BIT(key, i ^ 7);
  36         }
  37         return;
  38 }
  39 void crypto1_destroy(struct Crypto1State *state)
  40 {
  41         state->odd = 0;
  42         state->even = 0;
  43 }
  44 #else
  45 struct Crypto1State * crypto1_create(uint64_t key)
  46 {
  47         struct Crypto1State *s = malloc(sizeof(*s));
  48         int i;
  49
  50         for(i = 47;s && i > 0; i -= 2) {
  51                 s->odd  = s->odd  << 1 | BIT(key, (i - 1) ^ 7);
  52                 s->even = s->even << 1 | BIT(key, i ^ 7);
  53         }
  54         return s;
  55 }
  56 void crypto1_destroy(struct Crypto1State *state)
  57 {
  58         free(state);
  59 }
  60 #endif
  61 void crypto1_get_lfsr(struct Crypto1State *state, uint64_t *lfsr)
  62 {
  63         int i;
  64         for(*lfsr = 0, i = 23; i >= 0; --i) {
  65                 *lfsr = *lfsr << 1 | BIT(state->odd, i ^ 3);
  66                 *lfsr = *lfsr << 1 | BIT(state->even, i ^ 3);
  67         }
  68 }
  69 uint8_t crypto1_bit(struct Crypto1State *s, uint8_t in, int is_encrypted)
  70 {
  71         uint32_t feedin, t;
  72         uint8_t ret = filter(s->odd);
  73
  74         feedin  = ret & !!is_encrypted;
  75         feedin ^= !!in;
  76         feedin ^= LF_POLY_ODD & s->odd;
  77         feedin ^= LF_POLY_EVEN & s->even;
  78         s->even = s->even << 1 | evenparity32(feedin);
  79
  80         t = s->odd, s->odd = s->even, s->even = t;
  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 < 32; ++i)
  98                 ret |= crypto1_bit(s, BEBIT(in, i), is_encrypted) << (i ^ 24);
  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 }