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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__) && !defined(__linux__) && !defined(_WIN32) // bare metal ARM lacks malloc()/free()
27 void crypto1_create(struct Crypto1State *s, uint64_t key)
28 {
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;
36 }
37 void crypto1_destroy(struct Crypto1State *state)
38 {
39 state->odd = 0;
40 state->even = 0;
41 }
42 #else
43 struct Crypto1State * crypto1_create(uint64_t key)
44 {
45 struct Crypto1State *s = malloc(sizeof(*s));
46 int i;
47
48 for(i = 47;s && i > 0; i -= 2) {
49 s->odd = s->odd << 1 | BIT(key, (i - 1) ^ 7);
50 s->even = s->even << 1 | BIT(key, i ^ 7);
51 }
52 return s;
53 }
54 void crypto1_destroy(struct Crypto1State *state)
55 {
56 free(state);
57 }
58 #endif
59 void crypto1_get_lfsr(struct Crypto1State *state, uint64_t *lfsr)
60 {
61 int i;
62 for(*lfsr = 0, i = 23; i >= 0; --i) {
63 *lfsr = *lfsr << 1 | BIT(state->odd, i ^ 3);
64 *lfsr = *lfsr << 1 | BIT(state->even, i ^ 3);
65 }
66 }
67 uint8_t crypto1_bit(struct Crypto1State *s, uint8_t in, int is_encrypted)
68 {
69 uint32_t feedin, t;
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 t = s->odd, s->odd = s->even, s->even = t;
79
80 return ret;
81 }
82 uint8_t crypto1_byte(struct Crypto1State *s, uint8_t in, int is_encrypted)
83 {
84 uint8_t i, ret = 0;
85
86 for (i = 0; i < 8; ++i)
87 ret |= crypto1_bit(s, BIT(in, i), is_encrypted) << i;
88
89 return ret;
90 }
91 uint32_t crypto1_word(struct Crypto1State *s, uint32_t in, int is_encrypted)
92 {
93 uint32_t i, ret = 0;
94
95 for (i = 0; i < 32; ++i)
96 ret |= crypto1_bit(s, BEBIT(in, i), is_encrypted) << (i ^ 24);
97
98 return ret;
99 }
100
101 /* prng_successor
102 * helper used to obscure the keystream during authentication
103 */
104 uint32_t prng_successor(uint32_t x, uint32_t n)
105 {
106 SWAPENDIAN(x);
107 while(n--)
108 x = x >> 1 | (x >> 16 ^ x >> 18 ^ x >> 19 ^ x >> 21) << 31;
109
110 return SWAPENDIAN(x);
111 }
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