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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 }
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