7847961b |
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 < 32; ++i) |
78 | ret |= crypto1_bit(s, BEBIT(in, i), is_encrypted) << (i ^ 24); |
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 | } |