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1 //-----------------------------------------------------------------------------

3 // 2015 Dake <thomas.cayrou at gmail.com>

4 // 2018 sguerrini97 <sguerrini97 at gmail.com>

6 // This code is licensed to you under the terms of the GNU GPL, version 2 or,

7 // at your option, any later version. See the LICENSE.txt file for the text of

8 // the license.

9 //-----------------------------------------------------------------------------

10 // Low frequency PCF7931 commands

11 //-----------------------------------------------------------------------------

13 #include "cmdlfpcf7931.h"

15 #include <stdio.h>

16 #include <string.h>

17 #include "comms.h"

18 #include "ui.h"

19 #include "util.h"

20 #include "graph.h"

21 #include "cmdparser.h"

22 #include "cmddata.h"

23 #include "cmdmain.h"

24 #include "cmdlf.h"

 static int CmdHelp(const char *Cmd);

28 #define PCF7931_DEFAULT_INITDELAY 17500

29 #define PCF7931_DEFAULT_OFFSET_WIDTH 0

30 #define PCF7931_DEFAULT_OFFSET_POSITION 0

32 // Default values - Configuration

33 struct pcf7931_config configPcf = {

         {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF},

35 PCF7931_DEFAULT_INITDELAY,

36 PCF7931_DEFAULT_OFFSET_WIDTH,

37 PCF7931_DEFAULT_OFFSET_POSITION

38 };

40 // Resets the configuration settings to default values.

41 int pcf7931_resetConfig(){

         memset(configPcf.Pwd, 0xFF, sizeof(configPcf.Pwd) );

43 configPcf.InitDelay = PCF7931_DEFAULT_INITDELAY;

44 configPcf.OffsetWidth = PCF7931_DEFAULT_OFFSET_WIDTH;

45 configPcf.OffsetPosition = PCF7931_DEFAULT_OFFSET_POSITION;

46 return 0;

47 }

49 int pcf7931_printConfig(){

         PrintAndLog("Password (LSB first on bytes) : %s", sprint_hex( configPcf.Pwd, sizeof(configPcf.Pwd)));

         PrintAndLog("Tag initialization delay      : %d us", configPcf.InitDelay);

         PrintAndLog("Offset low pulses width       : %d us", configPcf.OffsetWidth);

         PrintAndLog("Offset low pulses position    : %d us", configPcf.OffsetPosition);

54 return 0;

55 }

57 int usage_pcf7931_read(){

58 PrintAndLog("Usage: lf pcf7931 read [h] ");

59 PrintAndLog("This command tries to read a PCF7931 tag.");

60 PrintAndLog("Options:");

61 PrintAndLog(" h This help");

62 PrintAndLog("Examples:");

63 PrintAndLog(" lf pcf7931 read");

64 return 0;

65 }

67 int usage_pcf7931_write(){

68 PrintAndLog("Usage: lf pcf7931 write [h] <block address> <byte address> <data>");

69 PrintAndLog("This command tries to write a PCF7931 tag.");

70 PrintAndLog("Options:");

71 PrintAndLog(" h This help");

72 PrintAndLog(" blockaddress Block to save [0-7]");

73 PrintAndLog(" byteaddress Index of byte inside block to write [0-15]");

74 PrintAndLog(" data one byte of data (hex)");

75 PrintAndLog("Examples:");

76 PrintAndLog(" lf pcf7931 write 2 1 FF");

77 return 0;

78 }

80 int usage_pcf7931_bruteforce()

81 {

82 PrintAndLog("Usage: lf pcf7931 bruteforce [h] <start password> <tries>");

83 PrintAndLog("This command tries to disable PAC of a PCF7931 transponder by bruteforcing the password.");

84 PrintAndLog("!! THIS IS NOT INTENDED TO RECOVER THE FULL PASSWORD !!");

85 PrintAndLog("!! DO NOT USE UNLESS THE FIRST 5 BYTES OF THE PASSWORD ARE KNOWN !!");

86 PrintAndLog("Options:");

87 PrintAndLog(" h This help");

88 PrintAndLog(" start password hex password to start from");

89 PrintAndLog(" tries How many times to send the same data frame");

90 PrintAndLog("Examples:");

91 PrintAndLog(" lf pcf7931 bruteforce 00000000123456 3");

92 return 0;

93 }

95 int usage_pcf7931_config(){

96 PrintAndLog("Usage: lf pcf7931 config [h] [r] <pwd> <delay> <offset width> <offset position>");

97 PrintAndLog("This command tries to set the configuration used with PCF7931 commands");

98 PrintAndLog("The time offsets could be useful to correct slew rate generated by the antenna");

99 PrintAndLog("Caling without some parameter will print the current configuration.");

100 PrintAndLog("Options:");

101 PrintAndLog(" h This help");

102 PrintAndLog(" r Reset configuration to default values");

103 PrintAndLog(" pwd Password, hex, 7bytes, LSB-order");

104 PrintAndLog(" delay Tag initialization delay (in us) decimal");

105 PrintAndLog(" offset Low pulses width (in us) decimal");

106 PrintAndLog(" offset Low pulses position (in us) decimal");

107 PrintAndLog("Examples:");

108 PrintAndLog(" lf pcf7931 config");

109 PrintAndLog(" lf pcf7931 config r");

110 PrintAndLog(" lf pcf7931 config 11223344556677 20000");

111 PrintAndLog(" lf pcf7931 config 11223344556677 17500 -10 30");

112 return 0;

113 }

114

 int CmdLFPCF7931Read(const char *Cmd){

116

         uint8_t ctmp = param_getchar(Cmd, 0);

         if ( ctmp == 'H' || ctmp == 'h' ) return usage_pcf7931_read();

119

120 UsbCommand resp;

         UsbCommand c = {CMD_PCF7931_READ, {0, 0, 0}};

122 clearCommandBuffer();

123 SendCommand(&c);

         if ( !WaitForResponseTimeout(CMD_ACK, &resp, 2500) ) {

125 PrintAndLog("command execution time out");

126 return 1;

127 }

128 return 0;

129 }

130

 int CmdLFPCF7931Config(const char *Cmd){

132

         uint8_t ctmp = param_getchar(Cmd, 0);

         if ( ctmp == 0) return pcf7931_printConfig();

         if ( ctmp == 'H' || ctmp == 'h' ) return usage_pcf7931_config();

         if ( ctmp == 'R' || ctmp == 'r' ) return pcf7931_resetConfig();

137

         if ( param_gethex(Cmd, 0, configPcf.Pwd, 14) ) return usage_pcf7931_config();

139

         configPcf.InitDelay = (param_get32ex(Cmd,1,0,10) & 0xFFFF);

         configPcf.OffsetWidth = (int)(param_get32ex(Cmd,2,0,10) & 0xFFFF);

         configPcf.OffsetPosition = (int)(param_get32ex(Cmd,3,0,10) & 0xFFFF);

143

144 pcf7931_printConfig();

145 return 0;

146 }

147

 int CmdLFPCF7931Write(const char *Cmd){

149

         uint8_t ctmp = param_getchar(Cmd, 0);

         if (strlen(Cmd) < 1 || ctmp == 'h' || ctmp == 'H') return usage_pcf7931_write();

152

         uint8_t block = 0, bytepos = 0, data = 0;

154

         if ( param_getdec(Cmd, 0, &block) ) return usage_pcf7931_write();

         if ( param_getdec(Cmd, 1, &bytepos) ) return usage_pcf7931_write();

157

         if ( (block > 7) || (bytepos > 15) ) return usage_pcf7931_write();

159

         data  = param_get8ex(Cmd, 2, 0, 16);

161

         PrintAndLog("Writing block: %d", block);

         PrintAndLog("          pos: %d", bytepos);

         PrintAndLog("         data: 0x%02X", data);

165

         UsbCommand c = {CMD_PCF7931_WRITE, { block, bytepos, data} };

         memcpy(c.d.asDwords, configPcf.Pwd, sizeof(configPcf.Pwd) );

           c.d.asDwords[7] = (configPcf.OffsetWidth + 128);

           c.d.asDwords[8] = (configPcf.OffsetPosition + 128);

           c.d.asDwords[9] = configPcf.InitDelay;

171

172 clearCommandBuffer();

173 SendCommand(&c);

174 //no ack?

175 return 0;

176 }

177

 int CmdLFPCF7931BruteForce(const char *Cmd){

179

         uint8_t ctmp = param_getchar(Cmd, 0);

         if (strlen(Cmd) < 1 || ctmp == 'h' || ctmp == 'H') return usage_pcf7931_bruteforce();

182

         uint8_t start_password[7] = {0};

184 uint8_t tries = 3;

185

         if (param_gethex(Cmd, 0, start_password, 14)) return usage_pcf7931_bruteforce();

         if (param_getdec(Cmd, 1, &tries)) return usage_pcf7931_bruteforce();

188

189 PrintAndLog("Bruteforcing from password: %02x %02x %02x %02x %02x %02x %02x",

190 start_password[0],

191 start_password[1],

192 start_password[2],

193 start_password[3],

194 start_password[4],

195 start_password[5],

196 start_password[6]);

197

         PrintAndLog("Trying each password %d times", tries);

199

         UsbCommand c = {CMD_PCF7931_BRUTEFORCE, {bytes_to_num(start_password, 7), tries} };

201

         c.d.asDwords[7] = (configPcf.OffsetWidth + 128);

         c.d.asDwords[8] = (configPcf.OffsetPosition + 128);

         c.d.asDwords[9] = configPcf.InitDelay;

205

206 clearCommandBuffer();

207 SendCommand(&c);

208 //no ack?

209 return 0;

210 }

211

212 static command_t CommandTable[] =

213 {

         {"help",   CmdHelp,            1, "This help"},

         {"read",   CmdLFPCF7931Read,   0, "Read content of a PCF7931 transponder"},

         {"write",  CmdLFPCF7931Write,  0, "Write data on a PCF7931 transponder."},

         {"config", CmdLFPCF7931Config, 1, "Configure the password, the tags initialization delay and time offsets (optional)"},

         {"bruteforce", CmdLFPCF7931BruteForce, 0, "Bruteforce a PCF7931 transponder password."},

         {NULL,     NULL,               0, NULL}

220 };

221

 int CmdLFPCF7931(const char *Cmd)

223 {

224 CmdsParse(CommandTable, Cmd);

225 return 0;

226 }

227

 int CmdHelp(const char *Cmd)

229 {

230 CmdsHelp(CommandTable);

231 return 0;

232 }