code: private String format(String algorithm, int iterations, byte[] salt, byte[] value) {
          final char COLON = ':';
          StringBuffer sb = new StringBuffer(algorithm);
          sb.append(COLON).append(iterations).append(COLON).append(Base64Coder.base64EncodeToString(salt)).append(COLON).append(Base64Coder.base64EncodeToString(value));
          return sb.toString();
      }
docs: <algorithm>:<iterations>:<base64(salt)>:<base64(hash)>