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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 | struct Crypto1State * crypto1_create(uint64_t key) | |
27 | { | |
28 | struct Crypto1State *s = malloc(sizeof(*s)); | |
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 s; | |
36 | } | |
37 | void crypto1_destroy(struct Crypto1State *state) | |
38 | { | |
39 | free(state); | |
40 | } | |
41 | void crypto1_get_lfsr(struct Crypto1State *state, uint64_t *lfsr) | |
42 | { | |
43 | int i; | |
44 | for(*lfsr = 0, i = 23; i >= 0; --i) { | |
45 | *lfsr = *lfsr << 1 | BIT(state->odd, i ^ 3); | |
46 | *lfsr = *lfsr << 1 | BIT(state->even, i ^ 3); | |
47 | } | |
48 | } | |
49 | uint8_t crypto1_bit(struct Crypto1State *s, uint8_t in, int is_encrypted) | |
50 | { | |
51 | uint32_t feedin; | |
52 | uint8_t ret = filter(s->odd); | |
53 | ||
54 | feedin = ret & !!is_encrypted; | |
55 | feedin ^= !!in; | |
56 | feedin ^= LF_POLY_ODD & s->odd; | |
57 | feedin ^= LF_POLY_EVEN & s->even; | |
58 | s->even = s->even << 1 | parity(feedin); | |
59 | ||
60 | s->odd ^= (s->odd ^= s->even, s->even ^= s->odd); | |
61 | ||
62 | return ret; | |
63 | } | |
64 | uint8_t crypto1_byte(struct Crypto1State *s, uint8_t in, int is_encrypted) | |
65 | { | |
66 | uint8_t i, ret = 0; | |
67 | ||
68 | for (i = 0; i < 8; ++i) | |
69 | ret |= crypto1_bit(s, BIT(in, i), is_encrypted) << i; | |
70 | ||
71 | return ret; | |
72 | } | |
73 | uint32_t crypto1_word(struct Crypto1State *s, uint32_t in, int is_encrypted) | |
74 | { | |
75 | uint32_t i, ret = 0; | |
76 | ||
77 | for (i = 0; i < 4; ++i, in <<= 8) | |
78 | ret = ret << 8 | crypto1_byte(s, in >> 24, is_encrypted); | |
79 | ||
80 | return ret; | |
81 | } | |
82 | ||
83 | /* prng_successor | |
84 | * helper used to obscure the keystream during authentication | |
85 | */ | |
86 | uint32_t prng_successor(uint32_t x, uint32_t n) | |
87 | { | |
88 | SWAPENDIAN(x); | |
89 | while(n--) | |
90 | x = x >> 1 | (x >> 16 ^ x >> 18 ^ x >> 19 ^ x >> 21) << 31; | |
91 | ||
92 | return SWAPENDIAN(x); | |
93 | } |