mirror of
https://github.com/RfidResearchGroup/proxmark3.git
synced 2024-09-20 23:36:31 +08:00
46 lines
1.6 KiB
C
46 lines
1.6 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.
|
|
//-----------------------------------------------------------------------------
|
|
// ISO14443 CRC calculation code.
|
|
//-----------------------------------------------------------------------------
|
|
|
|
#include "iso14443crc.h"
|
|
|
|
static unsigned short UpdateCrc14443(unsigned char ch, unsigned short *lpwCrc) {
|
|
ch = (ch ^ (unsigned char)((*lpwCrc) & 0x00FF));
|
|
ch = (ch ^ (ch << 4));
|
|
*lpwCrc = (*lpwCrc >> 8) ^ ((unsigned short) ch << 8) ^
|
|
((unsigned short) ch << 3) ^ ((unsigned short) ch >> 4);
|
|
return (*lpwCrc);
|
|
}
|
|
|
|
void ComputeCrc14443(int CrcType,
|
|
const unsigned char *Data, int Length,
|
|
unsigned char *TransmitFirst,
|
|
unsigned char *TransmitSecond) {
|
|
unsigned short wCrc = CrcType;
|
|
|
|
do {
|
|
unsigned char chBlock = *Data++;
|
|
UpdateCrc14443(chBlock, &wCrc);
|
|
} while (--Length);
|
|
|
|
if (CrcType == CRC_14443_B)
|
|
wCrc = ~wCrc; /* ISO/IEC 13239 (formerly ISO/IEC 3309) */
|
|
|
|
*TransmitFirst = (unsigned char)(wCrc & 0xFF);
|
|
*TransmitSecond = (unsigned char)((wCrc >> 8) & 0xFF);
|
|
return;
|
|
}
|
|
|
|
int CheckCrc14443(int CrcType, const unsigned char *Data, int Length) {
|
|
unsigned char b1;
|
|
unsigned char b2;
|
|
if (Length < 3) return 0;
|
|
ComputeCrc14443(CrcType, Data, Length - 2, &b1, &b2);
|
|
if ((b1 == Data[Length - 2]) && (b2 == Data[Length - 1])) return 1;
|
|
return 0;
|
|
}
|