code: function unsignEncryptedContent(content) {
      const newIndex = content.indexOf(SIGNING_KEY);
      const oldIndex = content.indexOf(SIGNING_KEY_OLD);
      if (newIndex === -1 && oldIndex === -1) {
          throw new Error("Invalid credentials content (unknown signature)");
      }
      return newIndex >= 0
          ? content.substr(SIGNING_KEY.length)
          : content.substr(SIGNING_KEY_OLD.length);
  }
docs: Remove the signature from encrypted content
  @private
  @param {String} content The encrypted text
  @returns {String} The unsigned encrypted key
  @throws {Error} Throws if no SIGNING_KEY is detected
  @see SIGNING_KEY