Nelmio\SecurityBundle\Encrypter::decrypt PHP Метод

    public function decrypt($input)
    {
        if (empty($input)) {
            return;
        }
        $encryptedData = base64_decode($input, true);
        $iv = substr($encryptedData, 0, $this->ivSize);
        if (strlen($iv) < $this->ivSize) {
            return;
        }
        $encryptedData = substr($encryptedData, $this->ivSize);
        $init = @mcrypt_generic_init($this->module, $this->secret, $iv);
        if ($init === false || $init < 0) {
            return;
        }
        return rtrim(mdecrypt_generic($this->module, $encryptedData), "");
    }

 public function testEncryption()
 {
     $encrypter = new Encrypter('secret', 'rijndael-128');
     $value = 'bar';
     $encryptedValue = $encrypter->encrypt($value);
     $this->assertNotEquals($encryptedValue, $value);
     $decrypted = $encrypter->decrypt($encryptedValue);
     $this->assertEquals($decrypted, $value);
 }