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1 //-----------------------------------------------------------------------------
2 //
3 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
4 // at your option, any later version. See the LICENSE.txt file for the text of
5 // the license.
6 //-----------------------------------------------------------------------------
7 // Low frequency G Prox II tag commands
8 // Biphase, rf/ , 96 bits (unknown key calc + some bits)
9 //-----------------------------------------------------------------------------
10 #include <stdio.h>
11 #include <string.h>
12 #include <inttypes.h>
13 #include "cmdlfgproxii.h"
14 #include "proxmark3.h"
15 #include "ui.h"
16 #include "util.h"
17 #include "graph.h"
18 #include "cmdparser.h"
19 #include "cmddata.h"
20 #include "cmdmain.h"
21 #include "cmdlf.h"
22 #include "lfdemod.h"
23 static int CmdHelp(const char *Cmd);
24
25 //by marshmellow
26 //attempts to demodulate and identify a G_Prox_II verex/chubb card
27 //WARNING: if it fails during some points it will destroy the DemodBuffer data
28 // but will leave the GraphBuffer intact.
29 //if successful it will push askraw data back to demod buffer ready for emulation
30 int CmdG_Prox_II_Demod(const char *Cmd)
31 {
32 if (!ASKbiphaseDemod(Cmd, false)){
33 if (g_debugMode) PrintAndLog("Error gProxII: ASKbiphaseDemod failed 1st try");
34 return 0;
35 }
36 size_t size = DemodBufferLen;
37 //call lfdemod.c demod for gProxII
38 int ans = gProxII_Demod(DemodBuffer, &size);
39 if (ans < 0){
40 if (g_debugMode) PrintAndLog("Error gProxII_Demod");
41 return 0;
42 }
43 //got a good demod of 96 bits
44 uint8_t ByteStream[8] = {0x00};
45 uint8_t xorKey=0;
46 size_t startIdx = ans + 6; //start after 6 bit preamble
47
48 uint8_t bits_no_spacer[90];
49 //so as to not mess with raw DemodBuffer copy to a new sample array
50 memcpy(bits_no_spacer, DemodBuffer + startIdx, 90);
51 // remove the 18 (90/5=18) parity bits (down to 72 bits (96-6-18=72))
52 size_t bitLen = removeParity(bits_no_spacer, 0, 5, 3, 90); //source, startloc, paritylen, ptype, length_to_run
53 if (bitLen != 72) {
54 if (g_debugMode) PrintAndLog("Error gProxII: spacer removal did not produce 72 bits: %u, start: %u", bitLen, startIdx);
55 return 0;
56 }
57 // get key and then get all 8 bytes of payload decoded
58 xorKey = (uint8_t)bytebits_to_byteLSBF(bits_no_spacer, 8);
59 for (size_t idx = 0; idx < 8; idx++) {
60 ByteStream[idx] = ((uint8_t)bytebits_to_byteLSBF(bits_no_spacer+8 + (idx*8),8)) ^ xorKey;
61 if (g_debugMode) PrintAndLog("byte %u after xor: %02x", (unsigned int)idx, ByteStream[idx]);
62 }
63 //now ByteStream contains 8 Bytes (64 bits) of decrypted raw tag data
64 //
65 uint8_t fmtLen = ByteStream[0]>>2;
66 uint32_t FC = 0;
67 uint32_t Card = 0;
68 //get raw 96 bits to print
69 uint32_t raw1 = bytebits_to_byte(DemodBuffer+ans,32);
70 uint32_t raw2 = bytebits_to_byte(DemodBuffer+ans+32, 32);
71 uint32_t raw3 = bytebits_to_byte(DemodBuffer+ans+64, 32);
72
73 if (fmtLen==36){
74 FC = ((ByteStream[3] & 0x7F)<<7) | (ByteStream[4]>>1);
75 Card = ((ByteStream[4]&1)<<19) | (ByteStream[5]<<11) | (ByteStream[6]<<3) | (ByteStream[7]>>5);
76 PrintAndLog("G-Prox-II Found: FmtLen %d, FC %u, Card %u", (int)fmtLen, FC, Card);
77 } else if(fmtLen==26){
78 FC = ((ByteStream[3] & 0x7F)<<1) | (ByteStream[4]>>7);
79 Card = ((ByteStream[4]&0x7F)<<9) | (ByteStream[5]<<1) | (ByteStream[6]>>7);
80 PrintAndLog("G-Prox-II Found: FmtLen %d, FC %u, Card %u", (int)fmtLen, FC, Card);
81 } else {
82 PrintAndLog("Unknown G-Prox-II Fmt Found: FmtLen %d",(int)fmtLen);
83 PrintAndLog("Decoded Raw: %s", sprint_hex(ByteStream, 8));
84 }
85 PrintAndLog("Raw: %08x%08x%08x", raw1,raw2,raw3);
86 setDemodBuf(DemodBuffer, 96, ans);
87 setClockGrid(g_DemodClock, g_DemodStartIdx + (ans*g_DemodClock));
88
89 return 1;
90 }
91 //by marshmellow
92 //see ASKDemod for what args are accepted
93 int CmdG_Prox_II_Read(const char *Cmd) {
94 // read lf silently
95 lf_read(true, 10000);
96 // demod and output viking ID
97 return CmdG_Prox_II_Demod(Cmd);
98 }
99
100 static command_t CommandTable[] = {
101 {"help", CmdHelp, 1, "This help"},
102 {"demod", CmdG_Prox_II_Demod, 1, "Demodulate a G Prox II tag from the GraphBuffer"},
103 {"read", CmdG_Prox_II_Read, 0, "Attempt to read and Extract tag data from the antenna"},
104 {NULL, NULL, 0, NULL}
105 };
106
107 int CmdLF_G_Prox_II(const char *Cmd) {
108 CmdsParse(CommandTable, Cmd);
109 return 0;
110 }
111
112 int CmdHelp(const char *Cmd) {
113 CmdsHelp(CommandTable);
114 return 0;
115 }
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