public static final boolean verifyPassword(String plaintextPass, String sha256CryptText)
  {
    if (sha256CryptText.startsWith("$5$"))
      {
        return sha256CryptText.equals(Sha256_crypt(plaintextPass, sha256CryptText, 0));
      }
    else
      {
        throw new RuntimeException("Bad sha256CryptText");
      }
  }