private static byte[] getBuildFingerprintAndDeviceSerial() {
    StringBuilder result = new StringBuilder();
    String fingerprint = Build.FINGERPRINT;
    if (fingerprint != null) {
      result.append(fingerprint);
    }
    String serial = Build.SERIAL;
    if (serial != null) {
      result.append(serial);
    }
    try {
      return result.toString().getBytes("UTF-8");
    } catch (UnsupportedEncodingException e) {
      throw new RuntimeException("UTF-8 encoding not supported");
    }
  }
Generates a device- and invocation-specific seed to be mixed into the
Linux PRNG.
java/com/google/android/apps/authenticator/util/PrngFixes.java