Libnfc:APDU example

野性酷女 2021-12-11 16:09 264阅读 0赞

[http://nfc-tools.org/index.php/Libnfc:APDU\_example][http_nfc-tools.org_index.php_Libnfc_APDU_example]

<table> 
 <tbody> 
  <tr> 
   <td> <h2>Contents</h2> &nbsp;[<a href="http://nfc-tools.org/index.php/Libnfc:APDU_example#" rel="nofollow">hide</a>]&nbsp; 
    <ul> 
     <li><a href="http://nfc-tools.org/index.php/Libnfc:APDU_example#Short_example_illustrating_how_to_exchange_APDUs_with_a_ISO14443-4_tag" rel="nofollow">1&nbsp;Short example illustrating how to exchange APDUs with a ISO14443-4 tag</a> 
      <ul> 
       <li><a href="http://nfc-tools.org/index.php/Libnfc:APDU_example#apdu_example.c" rel="nofollow">1.1&nbsp;apdu_example.c</a></li> 
       <li><a href="http://nfc-tools.org/index.php/Libnfc:APDU_example#To_compile_it" rel="nofollow">1.2&nbsp;To compile it</a></li> 
       <li><a href="http://nfc-tools.org/index.php/Libnfc:APDU_example#Testing..." rel="nofollow">1.3&nbsp;Testing...</a></li> 
      </ul></li> 
    </ul></td> 
  </tr> 
 </tbody> 
</table>

## Short example illustrating how to exchange APDUs with a [ISO14443][]\-4 tag ##

It can be downloaded here [as apdu\_example.c][as apdu_example.c].

### [apdu\_example.c][as apdu_example.c] ###

#include <stdlib.h>
    #include <string.h>
    #include <nfc/nfc.h>

To send APDUs, we'll use a little helper function with some debugging prints of exchanged APDUs:

int
    CardTransmit(nfc_device *pnd, uint8_t * capdu, size_t capdulen, uint8_t * rapdu, size_t * rapdulen)
    {
      int res;
      size_t  szPos;
      printf("=> ");
      for (szPos = 0; szPos < capdulen; szPos++) {
        printf("%02x ", capdu[szPos]);
      }
      printf("\n");
      if ((res = nfc_initiator_transceive_bytes(pnd, capdu, capdulen, rapdu, *rapdulen, 500)) < 0) {
        return -1;
      } else {
        *rapdulen = (size_t) res;
        printf("<= ");
        for (szPos = 0; szPos < *rapdulen; szPos++) {
          printf("%02x ", rapdu[szPos]);
        }
        printf("\n");
        return 0;
      }
    }

Start of main() is very similar to [quick\_start\_example][quick_start_example]:

int
    main(int argc, const char *argv[])
    {
      nfc_device *pnd;
      nfc_target nt;
      nfc_context *context;
      nfc_init(&context);
      if (context == NULL) {
        printf("Unable to init libnfc (malloc)\n");
        exit(EXIT_FAILURE);
      }
      const char *acLibnfcVersion = nfc_version();
      (void)argc;
      printf("%s uses libnfc %s\n", argv[0], acLibnfcVersion);
     
      pnd = nfc_open(context, NULL);
     
      if (pnd == NULL) {
        printf("ERROR: %s", "Unable to open NFC device.");
        exit(EXIT_FAILURE);
      }
      if (nfc_initiator_init(pnd) < 0) {
        nfc_perror(pnd, "nfc_initiator_init");
        exit(EXIT_FAILURE);
      }
     
      printf("NFC reader: %s opened\n", nfc_device_get_name(pnd));
     
      const nfc_modulation nmMifare = {
        .nmt = NMT_ISO14443A,
        .nbr = NBR_106,
      };

Smartcards need to get RATS, so make sure NP\_AUTO\_ISO14443\_4 is set to **true**, which is its default value, otherwise if e.g. you were doing some MIFARE stuff before, set it explicitly:

// nfc_set_property_bool(pnd, NP_AUTO_ISO14443_4, true);

Polling for target... indefinitely

printf("Polling for target...\n");
      while (nfc_initiator_select_passive_target(pnd, nmMifare, NULL, 0, &nt) <= 0);
      printf("Target detected!\n");

Now we can exchange APDUs, here we're reading a NFC-Forum Type4 Tag

uint8_t capdu[264];
      size_t capdulen;
      uint8_t rapdu[264];
      size_t rapdulen;
      // Select application
      memcpy(capdu, "\x00\xA4\x04\x00\x07\xd2\x76\x00\x00\x85\x01\x00", 12);
      capdulen=12;
      rapdulen=sizeof(rapdu);
      if (CardTransmit(pnd, capdu, capdulen, rapdu, &rapdulen) < 0)
        exit(EXIT_FAILURE);
      if (rapdulen < 2 || rapdu[rapdulen-2] != 0x90 || rapdu[rapdulen-1] != 0x00)
        exit(EXIT_FAILURE);
      printf("Application selected!\n");
     
      // Select Capability Container
      memcpy(capdu, "\x00\xa4\x00\x0c\x02\xe1\x03", 7);  
      capdulen=7;
      rapdulen=sizeof(rapdu);
      if (CardTransmit(pnd, capdu, capdulen, rapdu, &rapdulen) < 0)
        exit(EXIT_FAILURE);
      if (rapdulen < 2 || rapdu[rapdulen-2] != 0x90 || rapdu[rapdulen-1] != 0x00) {
        capdu[3]='\x00'; // Maybe an older Tag4 ?
        if (CardTransmit(pnd, capdu, capdulen, rapdu, &rapdulen) < 0)
          exit(EXIT_FAILURE);
      }
      printf("Capability Container selected!\n");
     
      // Read Capability Container
      memcpy(capdu, "\x00\xb0\x00\x00\x0f", 5);  
      capdulen=5;
      rapdulen=sizeof(rapdu);
      if (CardTransmit(pnd, capdu, capdulen, rapdu, &rapdulen) < 0)
        exit(EXIT_FAILURE);
      if (rapdulen < 2 || rapdu[rapdulen-2] != 0x90 || rapdu[rapdulen-1] != 0x00)
        exit(EXIT_FAILURE);
      printf("Capability Container header:\n");
      size_t  szPos;
      for (szPos = 0; szPos < rapdulen-2; szPos++) {
        printf("%02x ", rapdu[szPos]);
      }
      printf("\n");

We're done!

nfc_close(pnd);
      nfc_exit(context);
      exit(EXIT_SUCCESS);
    }

### To compile it ###

It assumes libnfc is installed into the system

gcc -o apdu_example apdu_example.c -lnfc

### Testing... ###

$ ./apdu_example 
    ./apdu_example uses libnfc libnfc-1.7.0-43-ga1ef329
    NFC reader: SCM Micro / SCL3711-NFC&RW opened
    Polling for target...
    Target detected!
    => 00 a4 04 00 07 d2 76 00 00 85 01 00 
    <= 90 00 
    Application selected!
    => 00 a4 00 0c 02 e1 03 
    <= 6a 86 
    => 00 a4 00 00 02 e1 03 
    <= 90 00 
    Capability Container selected!
    => 00 b0 00 00 0f 
    <= 00 0f 10 00 3b 00 34 04 06 e1 04 0e e0 00 ff 90 00 
    Capability Container header:
    00 0f 10 00 3b 00 34 04 06 e1 04 0e e0 00 ff

[http_nfc-tools.org_index.php_Libnfc_APDU_example]: http://nfc-tools.org/index.php/Libnfc:APDU_example
[ISO14443]: http://nfc-tools.org/index.php/ISO14443
[as apdu_example.c]: http://nfc-tools.org/index.php?title=Libnfc:APDU_example&action=raw&anchor=apdu_example.c
[quick_start_example]: http://nfc-tools.org/index.php/Libnfc:quick_start_example