github/RRG-Proxmark3
1
0
Fork 0
mirror of https://github.com/RfidResearchGroup/proxmark3.git synced 2025-08-14 10:37:23 -07:00
Code Issues Projects Releases Packages Wiki Activity Actions

FIX: legic_prng.c according to user on forum ref: http://www.proxmark.org/forum/viewtopic.php?pid=5437#p5437 needs to be "& 0x7F"

Browse source 
ADD:  method for calculating the storage crc8.
This commit is contained in:
iceman1001 2016-02-12 12:34:05 +01:00
commit ee4e281675
3 changed files with 35 additions and 7 deletions
Download patch file Download diff file Expand all files Collapse all files

29
common/crc.c
View file

@ -6,6 +6,8 @@
// Generic CRC calculation code.
//-----------------------------------------------------------------------------
#include "crc.h"
#include "util.h"
#include <stdio.h>
#include <stdint.h>
#include <stddef.h>
@ -21,8 +23,7 @@ void crc_init(crc_t *crc, int order, uint32_t polynom, uint32_t initial_value, u
void crc_update(crc_t *crc, uint32_t data, int data_width)
{
int i;
for(i=0; i<data_width; i++) {
for( int i=0; i < data_width; i++) {
int oldstate = crc->state;
crc->state = crc->state >> 1;
if( (oldstate^data) & 1 ) {
@ -49,8 +50,28 @@ uint32_t CRC8Maxim(uint8_t *buff, size_t size)
crc_init(&crc, 9, 0x8c, 0x00, 0x00);
crc_clear(&crc);
for (size_t i=0; i < size; ++i){
for (size_t i=0; i < size; ++i)
crc_update(&crc, buff[i], 8);
}
return crc_finish(&crc);
}
uint32_t CRC8Legic(uint8_t *buff, size_t size) {
// Poly 0x63, reversed poly 0xC6, Init 0x55, Final 0x00
crc_t crc;
crc_init(&crc, 8, 0xC6, 0x55, 0);
crc_clear(&crc);
for ( int i = 0; i < size; ++i)
crc_update(&crc, buff[i], 8);
return SwapBits(crc_finish(&crc), 8);
}
uint32_t SwapBits(uint32_t value, int nrbits) {
uint32_t newvalue = 0;
for(int i = 0; i < nrbits; i++) {
newvalue ^= ((value >> i) & 1) << (nrbits - 1 - i);
}
return newvalue;
}

9
common/crc.h
View file

@ -26,7 +26,7 @@ typedef struct crc {
* final_xor is XORed onto the state before returning it from crc_result(). */
extern void crc_init(crc_t *crc, int order, uint32_t polynom, uint32_t initial_value, uint32_t final_xor);
/* Update the crc state. data is the data of length data_width bits (only the the
/* Update the crc state. data is the data of length data_width bits (only the
* data_width lower-most bits are used).
*/
extern void crc_update(crc_t *crc, uint32_t data, int data_width);
@ -38,7 +38,12 @@ extern void crc_clear(crc_t *crc);
extern uint32_t crc_finish(crc_t *crc);
// Calculate CRC-8/Maxim checksum
uint32_t CRC8Maxim(uint8_t *buff, size_t size );
uint32_t CRC8Maxim(uint8_t *buff, size_t size);
// Calculate CRC-8/Legic checksum
uint32_t CRC8Legic(uint8_t *buff, size_t size);
uint32_t SwapBits(uint32_t value, int nrbits);
/* Static initialization of a crc structure */
#define CRC_INITIALIZER(_order, _polynom, _initial_value, _final_xor) { \
.state = ((_initial_value) & ((1L<<(_order))-1)), \

4
common/legic_prng.c
View file

@ -26,7 +26,9 @@ void legic_prng_init(uint8_t init) {
void legic_prng_forward(int count) {
lfsr.c += count;
while(count--) {
lfsr.a = lfsr.a >> 1 | (lfsr.a ^ lfsr.a >> 6) << 6;
//lfsr.a = lfsr.a >> 1 | (lfsr.a ^ lfsr.a >> 6) << 6;
// According: http://www.proxmark.org/forum/viewtopic.php?pid=5437#p5437
lfsr.a = (lfsr.a >> 1 | (lfsr.a ^ lfsr.a >> 6) << 6) & 0x7F;
lfsr.b = lfsr.b >> 1 | (lfsr.b ^ lfsr.b >> 2 ^ lfsr.b >> 3 ^ lfsr.b >> 7) << 7;
}
}