Spring SAML - how to add custom fields on the SP HTTP request?

Question

My service provider uses HTTP-Post binding to send the request to the IDP. I need to add new fields to the form. Right now I'm sending the "SAMLRequest" and "RelayState", but I also need to send "option" and "profile", these are fields required by our IDP. How can I accomplish this with Spring Saml security?

Answer 1

You can include additional fields in the Extensions element of the SAML AuthnRequest message. In order to so you need to overriding class WebSSOProfileImpl and configure your new implementation class in the securityContext.xml. The Extensions element can be constructed for example like this:

package example;

import org.opensaml.common.SAMLException;
import org.opensaml.saml2.common.Extensions;
import org.opensaml.saml2.common.impl.ExtensionsBuilder;
import org.opensaml.saml2.core.AuthnRequest;
import org.opensaml.saml2.metadata.AssertionConsumerService;
import org.opensaml.saml2.metadata.SingleSignOnService;
import org.opensaml.saml2.metadata.provider.MetadataProviderException;
import org.opensaml.xml.schema.XSAny;
import org.opensaml.xml.schema.impl.XSAnyBuilder;
import org.springframework.security.saml.context.SAMLMessageContext;
import org.springframework.security.saml.metadata.MetadataManager;
import org.springframework.security.saml.processor.SAMLProcessor;
import org.springframework.security.saml.websso.WebSSOProfileImpl;
import org.springframework.security.saml.websso.WebSSOProfileOptions;

/**
 * Customization of the AuthnRequest generation.
 */
public class WebSSOProfile extends WebSSOProfileImpl {

    public WebSSOProfile() {
    }

    public WebSSOProfile(SAMLProcessor processor, MetadataManager manager) {
        super(processor, manager);
    }

    @Override
    protected AuthnRequest getAuthnRequest(SAMLMessageContext context, WebSSOProfileOptions options, AssertionConsumerService assertionConsumer, SingleSignOnService bindingService) throws SAMLException, MetadataProviderException {
        AuthnRequest authnRequest = super.getAuthnRequest(context, options, assertionConsumer, bindingService);
        authnRequest.setExtensions(buildExtensions());
        return authnRequest;
    }

    protected Extensions buildExtensions() {

        XSAny extraElement = new XSAnyBuilder().buildObject("urn:myexample:extraAttribute", "ExtraElement", "myexample");
        extraElement.setTextContent("extraValue");

        Extensions extensions = new ExtensionsBuilder().buildObject();
        extensions.getUnknownXMLObjects().add(extraElement);

        return extensions;

    }

}