mirror of
https://github.com/RfidResearchGroup/proxmark3.git
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90 lines
2.3 KiB
C
90 lines
2.3 KiB
C
//-----------------------------------------------------------------------------
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// This code is licensed to you under the terms of the GNU GPL, version 2 or,
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// at your option, any later version. See the LICENSE.txt file for the text of
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// the license.
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//-----------------------------------------------------------------------------
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// ISO15693 CRC & other commons
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//-----------------------------------------------------------------------------
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#include "iso15693tools.h"
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// The CRC as described in ISO 15693-Part 3-Annex C
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// v buffer with data
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// n length
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// returns crc as 16bit value
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uint16_t Iso15693Crc(uint8_t *v, int n)
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{
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uint32_t reg;
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int i, j;
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reg = 0xffff;
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for(i = 0; i < n; i++) {
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reg = reg ^ ((uint32_t)v[i]);
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for (j = 0; j < 8; j++) {
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if (reg & 0x0001) {
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reg = (reg >> 1) ^ 0x8408;
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} else {
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reg = (reg >> 1);
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}
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}
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}
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return ~(uint16_t)(reg & 0xffff);
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}
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// adds a CRC to a dataframe
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// req[] iso15963 frame without crc
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// n length without crc
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// returns the new length of the dataframe.
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int Iso15693AddCrc(uint8_t *req, int n) {
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uint16_t crc=Iso15693Crc(req,n);
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req[n] = crc & 0xff;
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req[n+1] = crc >> 8;
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return n+2;
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}
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int sprintf(char *str, const char *format, ...);
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// returns a string representation of the UID
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// UID is transmitted and stored LSB first, displayed MSB first
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// target char* buffer, where to put the UID, if NULL a static buffer is returned
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// uid[] the UID in transmission order
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// return: ptr to string
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char* Iso15693sprintUID(char *target, uint8_t *uid) {
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static char tempbuf[2*8+1] = {0};
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if (target==NULL) target=tempbuf;
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sprintf(target,"%02X%02X%02X%02X%02X%02X%02X%02X",
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uid[7],uid[6],uid[5],uid[4],uid[3],uid[2],uid[1],uid[0]);
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return target;
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}
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uint16_t iclass_crc16(char *data_p, unsigned short length)
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{
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unsigned char i;
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unsigned int data;
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uint16_t crc = 0xffff;
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if (length == 0)
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return (~crc);
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do
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{
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for (i=0, data=(unsigned int)0xff & *data_p++;
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i < 8;
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i++, data >>= 1)
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{
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if ((crc & 0x0001) ^ (data & 0x0001))
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crc = (crc >> 1) ^ POLY;
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else crc >>= 1;
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}
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} while (--length);
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crc = ~crc;
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data = crc;
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crc = (crc << 8) | (data >> 8 & 0xff);
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crc = crc ^ 0xBC3;
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return (crc);
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}
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