public function hashPassword($password, $strategyIdentifier = 'default')
    {
        /** @var $passwordHashingStrategy PasswordHashingStrategyInterface */
        list($passwordHashingStrategy, $strategyIdentifier) = $this->getPasswordHashingStrategyAndIdentifier($strategyIdentifier);
        $hashedPasswordAndSalt = $passwordHashingStrategy->hashPassword($password, $this->getEncryptionKey());
        return $strategyIdentifier . '=>' . $hashedPasswordAndSalt;
    }