94 lines
2.4 KiB
C
94 lines
2.4 KiB
C
/* crypto1.c
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, US
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Copyright (C) 2008-2008 bla <blapost@gmail.com>
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*/
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#include "crapto1.h"
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#include <stdlib.h>
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#define SWAPENDIAN(x)\
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(x = (x >> 8 & 0xff00ff) | (x & 0xff00ff) << 8, x = x >> 16 | x << 16)
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struct Crypto1State * crypto1_create(uint64_t key)
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{
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struct Crypto1State *s = malloc(sizeof(*s));
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int i;
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for(i = 47;s && i > 0; i -= 2) {
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s->odd = s->odd << 1 | BIT(key, (i - 1) ^ 7);
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s->even = s->even << 1 | BIT(key, i ^ 7);
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}
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return s;
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}
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void crypto1_destroy(struct Crypto1State *state)
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{
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free(state);
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}
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void crypto1_get_lfsr(struct Crypto1State *state, uint64_t *lfsr)
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{
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int i;
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for(*lfsr = 0, i = 23; i >= 0; --i) {
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*lfsr = *lfsr << 1 | BIT(state->odd, i ^ 3);
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*lfsr = *lfsr << 1 | BIT(state->even, i ^ 3);
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}
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}
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uint8_t crypto1_bit(struct Crypto1State *s, uint8_t in, int is_encrypted)
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{
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uint32_t feedin;
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uint8_t ret = filter(s->odd);
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feedin = ret & !!is_encrypted;
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feedin ^= !!in;
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feedin ^= LF_POLY_ODD & s->odd;
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feedin ^= LF_POLY_EVEN & s->even;
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s->even = s->even << 1 | parity(feedin);
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s->odd ^= (s->odd ^= s->even, s->even ^= s->odd);
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return ret;
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}
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uint8_t crypto1_byte(struct Crypto1State *s, uint8_t in, int is_encrypted)
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{
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uint8_t i, ret = 0;
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for (i = 0; i < 8; ++i)
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ret |= crypto1_bit(s, BIT(in, i), is_encrypted) << i;
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return ret;
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}
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uint32_t crypto1_word(struct Crypto1State *s, uint32_t in, int is_encrypted)
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{
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uint32_t i, ret = 0;
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for (i = 0; i < 32; ++i)
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ret |= crypto1_bit(s, BEBIT(in, i), is_encrypted) << (i ^ 24);
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return ret;
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}
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/* prng_successor
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* helper used to obscure the keystream during authentication
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*/
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uint32_t prng_successor(uint32_t x, uint32_t n)
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{
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SWAPENDIAN(x);
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while(n--)
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x = x >> 1 | (x >> 16 ^ x >> 18 ^ x >> 19 ^ x >> 21) << 31;
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return SWAPENDIAN(x);
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}
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