proxmark3/armsrc/crypto1.c

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