PollDesfire/poll_desfire.c

#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <err.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include "poll_desfire.h"

#define AID 0x22eaa0
#define RANDOM_UID_SIZE 8

void init_keys(MifareDESFireKey *null_key, MifareDESFireKey *master_key, char const *name) {
  uint8_t const key_data_null[8]  = {0, 0, 0, 0, 0, 0, 0, 0};
  *null_key = mifare_desfire_des_key_new_with_version(key_data_null);
  
  uint8_t key_data_real[16] = {0};
  {
    FILE *f = fopen(name, "rb");
    if (!f) {
      errx(EXIT_FAILURE, "error opening key file: %s", name);
    }
    if (fread(key_data_real, 1, sizeof key_data_real, f) < sizeof key_data_real) {
      errx(EXIT_FAILURE, "key file too small.");
    }
    fclose(f);
  }
  *master_key = mifare_desfire_aes_key_new(key_data_real);
}

int main(int argc, char **argv) {
  int error = EXIT_SUCCESS;

  nfc_context *context = NULL;
  nfc_device *device = NULL;
  FreefareTag *tags  = NULL;
  MifareDESFireKey key_null, key_master;
  MifareDESFireAID aid = mifare_desfire_aid_new(AID);

  error = init(&context, &device);
  init_keys(&key_null, &key_master, (argc > 1) ? argv[1] : "key");

  FILE *out = argc > 2 ? fopen(argv[2], "w") : stdout;

  while (true) {
    tags = freefare_get_tags(device);
    if (!tags) {
      nfc_close(device);
      errx(EXIT_FAILURE, "Error listing tags.");
    }

    for (int id = 0; tags[id]; id++) {
      FreefareTag tag = tags[id];
      if (MIFARE_DESFIRE != freefare_get_tag_type(tag))
        continue;
      
      char *tag_uid = freefare_get_tag_uid(tag);
      /* Result of various operations */
      int res;
      
      res = mifare_desfire_connect(tag);
      if (res < 0) {
        warnx("Can't connect to Mifare DESFire target.");
        goto next_tag;
      }

      if (mifare_desfire_select_application(tag, aid) != 0) {
        // Check for old card with our key as master key
        res = mifare_desfire_authenticate(tag, 0, key_master);
        if (res >= 0) {
          warnx("Old tag detected: %s", tag_uid);
          res = mifare_desfire_change_key(tag, 0, key_master, key_null);
        }
        
        // Card needs to have default null key as master
        res = mifare_desfire_authenticate(tag, 0, key_null);
        if (res < 0) {
          warnx("Could not authenticate: %d", res);
          goto next_tag;
        }

        // create application
        res = mifare_desfire_create_application_aes(tag, aid, MDAPP_SETTINGS(0, 1, 0, 0, 1), 1);
        if (res < 0) {
          warnx("Could not create application: %d", res);
          goto next_tag;
        }

        // Select it
        res = mifare_desfire_select_application(tag, aid);
        if (res < 0) {
          warnx("Application not selectable after creation: %d", res);
          goto next_tag;
        }

        // Key should be null
        res = mifare_desfire_authenticate_aes(tag, 0, key_null);
        if (res < 0) {
          warnx("Could not authenticate new application with default key: %d", res);
          goto next_tag;
        }

        // Update to our key
        res = mifare_desfire_change_key(tag, 0, key_master, key_null);
        if (res < 0) {
          warnx("Could not change key of new application to master key: %d", res);
          goto next_tag;
        }
      
        // Authenticate with new key
        res = mifare_desfire_authenticate_aes(tag, 0, key_master);
        if (res < 0) {
          warnx("Could not authenticate new application with our key: %d", res);
          goto next_tag;
        }

        // Create file
        res = mifare_desfire_create_std_data_file(tag, 0, 0, MDAR(0, 0, 0, 0), RANDOM_UID_SIZE);
        if (res < 0) {
          warnx("Could not create data file: %d", res);
          goto next_tag;
        }

        // Grab random data for it
        unsigned char uid_data[RANDOM_UID_SIZE];
        {
          int fd = open("/dev/urandom", O_RDONLY);
          if (fd < 0) {
            warnx("Could not open /dev/urandom");
            goto next_tag;
          }

          if (RANDOM_UID_SIZE != read(fd, &uid_data[0], RANDOM_UID_SIZE)) {
            warnx("Could not read data from /dev/random");
            goto next_tag;
          }
          close(fd);
        }

        // Write data
        res = mifare_desfire_write_data(tag, 0, 0, RANDOM_UID_SIZE, &uid_data[0]);
        if (res < 0) {
          warnx("Could not write UID data to tag: %d", res);
          goto next_tag;
        }
      }

      // Authenticate with our key
      res = mifare_desfire_authenticate_aes(tag, 0, key_master);
      if (res < 0) {
        warnx("Authentication on application failed: %d", res);
        goto next_tag;
      }

      // Grab UID
      uint8_t data[RANDOM_UID_SIZE];
      res = mifare_desfire_read_data(tag, 0, 0, RANDOM_UID_SIZE, &data[0]);
      if (res != RANDOM_UID_SIZE) {
        warnx("Could not read all bytes from tag: %d", res);
        goto next_tag;
      }

      // Print out key ID and UID
      fprintf(out, "%s:", tag_uid);
      for (int j = 0; j < RANDOM_UID_SIZE; j++) {
        fprintf(out, "%02x", data[j]);
      }
      fprintf(out, "\n");
      fflush(out);

next_tag:
      free(tag_uid);
      
      mifare_desfire_disconnect(tag);
    }

    while (freefare_selected_tag_is_present(device))
      ;
      
    freefare_free_tags(tags);
    fflush(stdout);
    fflush(stderr);
  }

  mifare_desfire_key_free(key_null);
  mifare_desfire_key_free(key_master);

  nfc_close(device);
  nfc_exit(context);

  exit(error);
}