Decrypt assertion

When the IdP sends encrypted assertions, the SP decrypts them automatically in handleAuthnResponse() — provided the Sp descriptor is configured with an encryption Certificate that includes a PrivateKey.

SP: configure decryption

use Litesaml\Models\Descriptors\Certificate;
use Litesaml\Models\Descriptors\Endpoint;
use Litesaml\Models\Descriptors\PrivateKey;
use Litesaml\Models\Descriptors\PublicKey;
use Litesaml\Models\Descriptors\Sp;
use Litesaml\Enums\BindingType;

$sp = new Sp(
    entityId: 'https://my-app.example.com',
    acs: new Endpoint('https://my-app.example.com/saml/acs', BindingType::POST),
    slo: new Endpoint('https://my-app.example.com/saml/slo', BindingType::REDIRECT),
    encryption: new Certificate(
        publicKey: new PublicKey(file_get_contents('/path/to/sp-enc-cert.pem')),
        privateKey: new PrivateKey(file_get_contents('/path/to/sp-enc-key.pem')),
    ),
);

Receiving the decrypted attributes

No extra code is needed. Call handleAuthnResponse() as usual:

$authnResponse = $spWrapper->handleAuthnResponse($request);

foreach ($authnResponse->attributes as $attribute) {
    echo $attribute->name;
    // $attribute->encrypted === true for attributes that were encrypted by the IdP
    print_r($attribute->values);
}

Encrypted attributes are decrypted transparently and merged into $authnResponse->attributes alongside any plaintext attributes. You can distinguish them by checking $attribute->encrypted.

Error handling

If the response contains an encrypted assertion and $sp->encryption is not configured or has no PrivateKey, handleAuthnResponse() throws a SamlException:

No encryption certificate configured to decrypt assertion

Make sure the SP's encryption certificate public key is published in the SP's metadata so the IdP can use it to encrypt. See Encrypt assertion and Generate metadata.

If the key is configured but decryption itself fails — wrong key, corrupted ciphertext, or an unsupported key transport algorithm — handleAuthnResponse() throws a SamlException with the message:

Failed to decrypt assertion: ...

Since litesaml/saml 5.0, assertions encrypted with RSA-1.5 key transport are rejected here by default (Bleichenbacher risk); the IdP must use RSA-OAEP. See Upgrading to 5.0 from 4.x.