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1 //-----------------------------------------------------------------------------
2 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
3 // at your option, any later version. See the LICENSE.txt file for the text of
4 // the license.
5 //-----------------------------------------------------------------------------
6 // ISO15693 CRC & other commons
7 //-----------------------------------------------------------------------------
8
9
10 #include "proxmark3.h"
11 #include <stdint.h>
12 #include <stdlib.h>
13 //#include "iso15693tools.h"
14
15 #define POLY 0x8408
16
17
18 // The CRC as described in ISO 15693-Part 3-Annex C
19 // v buffer with data
20 // n length
21 // returns crc as 16bit value
22 uint16_t Iso15693Crc(uint8_t *v, int n)
23 {
24 uint32_t reg;
25 int i, j;
26
27 reg = 0xffff;
28 for(i = 0; i < n; i++) {
29 reg = reg ^ ((uint32_t)v[i]);
30 for (j = 0; j < 8; j++) {
31 if (reg & 0x0001) {
32 reg = (reg >> 1) ^ 0x8408;
33 } else {
34 reg = (reg >> 1);
35 }
36 }
37 }
38
39 return ~(uint16_t)(reg & 0xffff);
40 }
41
42 // adds a CRC to a dataframe
43 // req[] iso15963 frame without crc
44 // n length without crc
45 // returns the new length of the dataframe.
46 int Iso15693AddCrc(uint8_t *req, int n) {
47 uint16_t crc=Iso15693Crc(req,n);
48 req[n] = crc & 0xff;
49 req[n+1] = crc >> 8;
50 return n+2;
51 }
52
53
54 int sprintf(char *str, const char *format, ...);
55
56 // returns a string representation of the UID
57 // UID is transmitted and stored LSB first, displayed MSB first
58 // target char* buffer, where to put the UID, if NULL a static buffer is returned
59 // uid[] the UID in transmission order
60 // return: ptr to string
61 char* Iso15693sprintUID(char *target,uint8_t *uid) {
62 static char tempbuf[2*8+1]="";
63 if (target==NULL) target=tempbuf;
64 sprintf(target,"%02X%02X%02X%02X%02X%02X%02X%02X",
65 uid[7],uid[6],uid[5],uid[4],uid[3],uid[2],uid[1],uid[0]);
66 return target;
67 }
68
69 uint16_t iclass_crc16(char *data_p, unsigned short length)
70 {
71 unsigned char i;
72 unsigned int data;
73 uint16_t crc = 0xffff;
74
75 if (length == 0)
76 return (~crc);
77
78 do
79 {
80 for (i=0, data=(unsigned int)0xff & *data_p++;
81 i < 8;
82 i++, data >>= 1)
83 {
84 if ((crc & 0x0001) ^ (data & 0x0001))
85 crc = (crc >> 1) ^ POLY;
86 else crc >>= 1;
87 }
88 } while (--length);
89
90 crc = ~crc;
91 data = crc;
92 crc = (crc << 8) | (data >> 8 & 0xff);
93 crc = crc ^ 0xBC3;
94 return (crc);
95 }
96
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