Encrypt Assertion

Light Saml supports SAML Assertion encryption. First you need normally to create the Assertion with all the data you need. Then create a new instance of EncryptedAssertionWriter and call it's encrypt method with the created assertion object and certificate of the recipient. Finally, assign that encryption writer to the SAML Response.

<?php
$assertion = new Assertion();
// fill it up with data...
$certificate = X509Certificate::fromFile('/path/to/saml.crt');
$encryptedAssertion = new EncryptedAssertionWriter();
$encryptedAssertion->encrypt($assertion, KeyHelper::createPublicKey($certificate));
$response = new Response();
$response->addEncryptedAssertion($encryptedAssertion);
$context = new SerializationContext();
$response->serialize($context->getDocument(), $context);

Note: The SAML protocol also specifies that Assertion should be signed before encryption, while during receiving the Assertion procedure is reversed - you first decrypt it, and then verify its signature.