Review

class PassportAuthService {
   /**
    * Performs the <i>Basic Access Control</i> protocol.
    *
    * @param docNr the document number
    * @param dateOfBirth card holder's birth date
    * @param dateOfExpiry document's expiry date
    */
   public void doBAC(String docNr, String dateOfBirth, String dateOfExpiry)
         throws GeneralSecurityException, UnsupportedEncodingException {
      byte[] keySeed = Util.computeKeySeed(docNr, dateOfBirth, dateOfExpiry);
      SecretKey kEnc = Util.deriveKey(keySeed, Util.ENC_MODE);
      SecretKey kMac = Util.deriveKey(keySeed, Util.MAC_MODE);
      byte[] rndICC = service.sendGetChallenge();
      byte[] rndIFD = new byte[8]; /* random */
      byte[] kIFD = new byte[16]; /* random */
      byte[] response = service.sendMutualAuth(rndIFD, rndICC, kIFD, kEnc, kMac);
      byte[] kICC = new byte[16];
      System.arraycopy(response, 16, kICC, 0, 16);
      keySeed = new byte[16];
      for (int i = 0; i < 16; i++) {
         keySeed[i] = (byte) ((kIFD[i] & 0x000000FF) ^ (kICC[i] & 0x000000FF));
      }
      SecretKey ksEnc = Util.deriveKey(keySeed, Util.ENC_MODE);
      SecretKey ksMac = Util.deriveKey(keySeed, Util.MAC_MODE);
      long ssc = Util.computeSendSequenceCounter(rndICC, rndIFD);
      wrapper = new SecureMessagingWrapper(ksEnc, ksMac, ssc);
      notifyBACPerformed(wrapper, rndICC, rndIFD, kIFD, kICC, true);
      state = BAC_AUTHENTICATED_STATE;
   }

}