proxmark3/common/iso15693tools.c
pwpiwi 28ae37b746
fix 'hf iclass replay' (#888)
* implement option -n for authentication with replayed NR/MAC pairs in 'dump' and 'readbl'
* delete 'hf iclass replay'
2019-12-04 18:34:53 +01:00

96 lines
2.4 KiB
C

//-----------------------------------------------------------------------------
// This code is licensed to you under the terms of the GNU GPL, version 2 or,
// at your option, any later version. See the LICENSE.txt file for the text of
// the license.
//-----------------------------------------------------------------------------
// ISO15693 CRC & other commons
//-----------------------------------------------------------------------------
#include "iso15693tools.h"
#include <stddef.h>
#include <stdint.h>
#ifdef ON_DEVICE
#include "printf.h"
#else
#include <stdio.h>
#endif
#define ISO15693_CRC_PRESET (uint16_t)0xFFFF
#define ISO15693_CRC_POLY (uint16_t)0x8408
// The CRC as described in ISO 15693-Part 3-Annex C
// v buffer with data
// n length
// returns crc as 16bit value
uint16_t Iso15693Crc(uint8_t *v, int n) {
uint32_t reg;
int i, j;
reg = ISO15693_CRC_PRESET;
for (i = 0; i < n; i++) {
reg = reg ^ ((uint32_t)v[i]);
for (j = 0; j < 8; j++) {
if (reg & 0x0001) {
reg = (reg >> 1) ^ ISO15693_CRC_POLY;
} else {
reg = (reg >> 1);
}
}
}
return ~(uint16_t)(reg & 0xffff);
}
// adds a CRC to a dataframe
// req[] iso15963 frame without crc
// n length without crc
// returns the new length of the dataframe.
int Iso15693AddCrc(uint8_t *req, int n) {
uint16_t crc = Iso15693Crc(req, n);
req[n] = crc & 0xff;
req[n+1] = crc >> 8;
return n + 2;
}
// returns a string representation of the UID
// UID is transmitted and stored LSB first, displayed MSB first
// target char* buffer, where to put the UID, if NULL a static buffer is returned
// uid[] the UID in transmission order
// return: ptr to string
char* Iso15693sprintUID(char *target, uint8_t *uid) {
static char tempbuf[2*8+1] = "";
if (target == NULL) target = tempbuf;
sprintf(target, "%02X%02X%02X%02X%02X%02X%02X%02X", uid[7], uid[6], uid[5], uid[4], uid[3], uid[2], uid[1], uid[0]);
return target;
}
uint16_t iclass_crc16(uint8_t *data_p, unsigned short length) {
unsigned char i;
unsigned int data;
uint16_t crc = ISO15693_CRC_PRESET;
if (length == 0)
return (~crc);
do {
for (i = 0, data = 0xff & *data_p++; i < 8; i++, data >>= 1) {
if ((crc & 0x0001) ^ (data & 0x0001))
crc = (crc >> 1) ^ ISO15693_CRC_POLY;
else crc >>= 1;
}
} while (--length);
crc = ~crc;
data = crc;
crc = (crc << 8) | (data >> 8 & 0xff);
crc = crc ^ 0x0BC3;
return (crc);
}