hasMatchingPassphrases_(passphrases) {
    if (passphrases.length < 2) {
      return false;
    }

    var masterPassphrase = passphrases[0];
    return goog.array.every(passphrases, function(passphrase) {
      return masterPassphrase == passphrase;
    });
  }
Returns true if the provided passphrases match.
@param {!Array.<string>} passphrases The passphrases to check.
@return {boolean} True if the provided passphrases match.
@private