SAML2\Assertion::encryptNameId PHP Method

    public function encryptNameId(XMLSecurityKey $key)
    {
        /* First create a XML representation of the NameID. */
        $doc = DOMDocumentFactory::create();
        $root = $doc->createElement('root');
        $doc->appendChild($root);
        Utils::addNameId($root, $this->nameId);
        $nameId = $root->firstChild;
        Utils::getContainer()->debugMessage($nameId, 'encrypt');
        /* Encrypt the NameID. */
        $enc = new XMLSecEnc();
        $enc->setNode($nameId);
        // @codingStandardsIgnoreStart
        $enc->type = XMLSecEnc::Element;
        // @codingStandardsIgnoreEnd
        $symmetricKey = new XMLSecurityKey(XMLSecurityKey::AES128_CBC);
        $symmetricKey->generateSessionKey();
        $enc->encryptKey($key, $symmetricKey);
        $this->encryptedNameId = $enc->encryptNode($symmetricKey);
        $this->nameId = null;
    }

 /**
  * Test NameID Encryption and Decryption.
  */
 public function testNameIdEncryption()
 {
     // Create an assertion
     $assertion = new Assertion();
     $assertion->setIssuer('testIssuer');
     $assertion->setValidAudiences(array('audience1', 'audience2'));
     $assertion->setAuthnContext('someAuthnContext');
     $assertion->setNameId(array("Value" => "just_a_basic_identifier", "Format" => "urn:oasis:names:tc:SAML:2.0:nameid-format:transient"));
     $this->assertFalse($assertion->isNameIdEncrypted());
     $publicKey = CertificatesMock::getPublicKey();
     $assertion->encryptNameId($publicKey);
     $this->assertTrue($assertion->isNameIdEncrypted());
     // Marshall it to a \DOMElement
     $assertionElement = $assertion->toXML()->ownerDocument->saveXML();
     $assertionToVerify = new Assertion(DOMDocumentFactory::fromString($assertionElement)->firstChild);
     $this->assertTrue($assertionToVerify->isNameIdEncrypted());
     $privateKey = CertificatesMock::getPrivateKey();
     $assertionToVerify->decryptNameId($privateKey);
     $this->assertFalse($assertionToVerify->isNameIdEncrypted());
     $nameID = $assertionToVerify->getNameID();
     $this->assertEquals('just_a_basic_identifier', $nameID['Value']);
     $this->assertEquals('urn:oasis:names:tc:SAML:2.0:nameid-format:transient', $nameID['Format']);
 }