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[proxmark3-svn] / 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 }
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