How to create a valid SAML 2.0 Assertion with OpenSAML for JAVA

Publiziert am 27. Juli 2010 von Christoph

Recently I had to implement SAML 2.0 for a client project for a Single Sign On (SSO) process.
For this purpose our system needed to create a SAML Assertion containing all the information of the user who is currently logging in.

I was using the OpenSAML classes for JAVA.
Initially I had some issues because I couldn’t find good documentation / examples about what how such an Assertion is to be created using OpenSAML.

I had to do lots of googling and trial & error and finally I got it working.
The following sites were useful and led to my solution.
- http://blogs.sun.com/JoachimAndres/entry/creating_a_saml_assertion_with1
- http://www.capcourse.com/Library/OpenSAML/index.html
- http://ekschi.com/technology/2009/09/01/creating-a-saml-assertion-with-opensaml-part-2/

Though I had to make modifications to some of the solutions above.

To save you this pain, I am posting my final example here. The class below is only for demonstration purposes of this blog entry, and I have stripped out lots of other stuff (e.g. error handling, client specific stuff, encryption via EncryptedAssertion). The only purpose is to give you some kind of template and idea how to start.

import java.util.HashMap;
import java.util.Map;
import java.util.Set;
 
import org.joda.time.DateTime;
import org.opensaml.Configuration;
import org.opensaml.DefaultBootstrap;
import org.opensaml.common.SAMLObjectBuilder;
import org.opensaml.common.SAMLVersion;
import org.opensaml.saml2.core.Assertion;
import org.opensaml.saml2.core.Attribute;
import org.opensaml.saml2.core.AttributeStatement;
import org.opensaml.saml2.core.AttributeValue;
import org.opensaml.saml2.core.AuthnContext;
import org.opensaml.saml2.core.AuthnContextClassRef;
import org.opensaml.saml2.core.AuthnStatement;
import org.opensaml.saml2.core.Condition;
import org.opensaml.saml2.core.Conditions;
import org.opensaml.saml2.core.Issuer;
import org.opensaml.saml2.core.NameID;
import org.opensaml.saml2.core.OneTimeUse;
import org.opensaml.saml2.core.Subject;
import org.opensaml.saml2.core.SubjectConfirmation;
import org.opensaml.saml2.core.SubjectConfirmationData;
import org.opensaml.saml2.core.impl.AssertionMarshaller;
import org.opensaml.xml.ConfigurationException;
import org.opensaml.xml.XMLObjectBuilder;
import org.opensaml.xml.XMLObjectBuilderFactory;
import org.opensaml.xml.io.MarshallingException;
import org.opensaml.xml.schema.XSString;
import org.opensaml.xml.util.XMLHelper;
import org.w3c.dom.Element;
 
/**
 * This is a demo class which creates a valid SAML 2.0 Assertion.
 */
public class SAMLWriter
{
 
 public static void main(String[] args) {
     try {
   SAMLInputContainer input = new SAMLInputContainer();
   input.strIssuer = "http://synesty.com";
   input.strNameID = "UserJohnSmith";
   input.strNameQualifier = "My Website";
   input.sessionId = "abcdedf1234567";
 
   Map customAttributes = new HashMap();
   customAttributes.put("FirstName", "John");
   customAttributes.put("LastName", "Smith");
 
   input.attributes = customAttributes;
 
   Assertion assertion = SAMLWriter.buildDefaultAssertion(input);
   AssertionMarshaller marshaller = new AssertionMarshaller();
   Element plaintextElement = marshaller.marshall(assertion);
   String originalAssertionString = XMLHelper.nodeToString(plaintextElement);
 
   System.out.println("Assertion String: " + originalAssertionString);
 
   // TODO: now you can also add encryption....
 
  } catch (MarshallingException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
 
 }
 
 private static XMLObjectBuilderFactory builderFactory;
 
 public static XMLObjectBuilderFactory getSAMLBuilder() throws ConfigurationException{
 
  if(builderFactory == null){
   // OpenSAML 2.3
    DefaultBootstrap.bootstrap();
          builderFactory = Configuration.getBuilderFactory();
  }
 
  return builderFactory;
 }
 
 /**
  * Builds a SAML Attribute of type String
  * @param name
  * @param value
  * @param builderFactory
  * @return
  * @throws ConfigurationException
  */
 public static Attribute buildStringAttribute(String name, String value, XMLObjectBuilderFactory builderFactory) throws ConfigurationException
 {
  SAMLObjectBuilder attrBuilder = (SAMLObjectBuilder) getSAMLBuilder().getBuilder(Attribute.DEFAULT_ELEMENT_NAME);
   Attribute attrFirstName = (Attribute) attrBuilder.buildObject();
   attrFirstName.setName(name);
 
   // Set custom Attributes
   XMLObjectBuilder stringBuilder = getSAMLBuilder().getBuilder(XSString.TYPE_NAME);
   XSString attrValueFirstName = (XSString) stringBuilder.buildObject(AttributeValue.DEFAULT_ELEMENT_NAME, XSString.TYPE_NAME);
   attrValueFirstName.setValue(value);
 
   attrFirstName.getAttributeValues().add(attrValueFirstName);
  return attrFirstName;
 }
 
 /**
  * Helper method which includes some basic SAML fields which are part of almost every SAML Assertion.
  *
  * @param input
  * @return
  */
 public static Assertion buildDefaultAssertion(SAMLInputContainer input)
 {
  try
  {
          // Create the NameIdentifier
          SAMLObjectBuilder nameIdBuilder = (SAMLObjectBuilder) SAMLWriter.getSAMLBuilder().getBuilder(NameID.DEFAULT_ELEMENT_NAME);
          NameID nameId = (NameID) nameIdBuilder.buildObject();
          nameId.setValue(input.getStrNameID());
          nameId.setNameQualifier(input.getStrNameQualifier());
          nameId.setFormat(NameID.UNSPECIFIED);
 
          // Create the SubjectConfirmation
 
          SAMLObjectBuilder confirmationMethodBuilder = (SAMLObjectBuilder)  SAMLWriter.getSAMLBuilder().getBuilder(SubjectConfirmationData.DEFAULT_ELEMENT_NAME);
          SubjectConfirmationData confirmationMethod = (SubjectConfirmationData) confirmationMethodBuilder.buildObject();
          DateTime now = new DateTime();
          confirmationMethod.setNotBefore(now);
          confirmationMethod.setNotOnOrAfter(now.plusMinutes(2));
 
          SAMLObjectBuilder subjectConfirmationBuilder = (SAMLObjectBuilder) SAMLWriter.getSAMLBuilder().getBuilder(SubjectConfirmation.DEFAULT_ELEMENT_NAME);
          SubjectConfirmation subjectConfirmation = (SubjectConfirmation) subjectConfirmationBuilder.buildObject();
          subjectConfirmation.setSubjectConfirmationData(confirmationMethod);
 
          // Create the Subject
          SAMLObjectBuilder subjectBuilder = (SAMLObjectBuilder) SAMLWriter.getSAMLBuilder().getBuilder(Subject.DEFAULT_ELEMENT_NAME);
          Subject subject = (Subject) subjectBuilder.buildObject();
 
          subject.setNameID(nameId);
          subject.getSubjectConfirmations().add(subjectConfirmation);
 
          // Create Authentication Statement
          SAMLObjectBuilder authStatementBuilder = (SAMLObjectBuilder) SAMLWriter.getSAMLBuilder().getBuilder(AuthnStatement.DEFAULT_ELEMENT_NAME);
          AuthnStatement authnStatement = (AuthnStatement) authStatementBuilder.buildObject();
          //authnStatement.setSubject(subject);
          //authnStatement.setAuthenticationMethod(strAuthMethod);
          DateTime now2 = new DateTime();
          authnStatement.setAuthnInstant(now2);
          authnStatement.setSessionIndex(input.getSessionId());
          authnStatement.setSessionNotOnOrAfter(now2.plus(input.getMaxSessionTimeoutInMinutes()));
 
          SAMLObjectBuilder authContextBuilder = (SAMLObjectBuilder) SAMLWriter.getSAMLBuilder().getBuilder(AuthnContext.DEFAULT_ELEMENT_NAME);
          AuthnContext authnContext = (AuthnContext) authContextBuilder.buildObject();
 
          SAMLObjectBuilder authContextClassRefBuilder = (SAMLObjectBuilder) SAMLWriter.getSAMLBuilder().getBuilder(AuthnContextClassRef.DEFAULT_ELEMENT_NAME);
          AuthnContextClassRef authnContextClassRef = (AuthnContextClassRef) authContextClassRefBuilder.buildObject();
          authnContextClassRef.setAuthnContextClassRef("urn:oasis:names:tc:SAML:2.0:ac:classes:Password"); // TODO not sure exactly about this
 
   authnContext.setAuthnContextClassRef(authnContextClassRef);
         authnStatement.setAuthnContext(authnContext);
 
         // Builder Attributes
          SAMLObjectBuilder attrStatementBuilder = (SAMLObjectBuilder) SAMLWriter.getSAMLBuilder().getBuilder(AttributeStatement.DEFAULT_ELEMENT_NAME);
          AttributeStatement attrStatement = (AttributeStatement) attrStatementBuilder.buildObject();
 
       // Create the attribute statement
          Map attributes = input.getAttributes();
          if(attributes != null){
           Set keySet = attributes.keySet();
           for (String key : keySet)
    {
            Attribute attrFirstName = buildStringAttribute(key, attributes.get(key), getSAMLBuilder());
            attrStatement.getAttributes().add(attrFirstName);
    }
          }
 
          // Create the do-not-cache condition
          SAMLObjectBuilder doNotCacheConditionBuilder = (SAMLObjectBuilder) SAMLWriter.getSAMLBuilder().getBuilder(OneTimeUse.DEFAULT_ELEMENT_NAME);
          Condition condition = (Condition) doNotCacheConditionBuilder.buildObject();
 
          SAMLObjectBuilder conditionsBuilder = (SAMLObjectBuilder) SAMLWriter.getSAMLBuilder().getBuilder(Conditions.DEFAULT_ELEMENT_NAME);
          Conditions conditions = (Conditions) conditionsBuilder.buildObject();
          conditions.getConditions().add(condition);
 
          // Create Issuer
          SAMLObjectBuilder issuerBuilder = (SAMLObjectBuilder) SAMLWriter.getSAMLBuilder().getBuilder(Issuer.DEFAULT_ELEMENT_NAME);
          Issuer issuer = (Issuer) issuerBuilder.buildObject();
          issuer.setValue(input.getStrIssuer());
 
          // Create the assertion
          SAMLObjectBuilder assertionBuilder = (SAMLObjectBuilder) SAMLWriter.getSAMLBuilder().getBuilder(Assertion.DEFAULT_ELEMENT_NAME);
          Assertion assertion = (Assertion) assertionBuilder.buildObject();
          assertion.setIssuer(issuer);
          assertion.setIssueInstant(now);
          assertion.setVersion(SAMLVersion.VERSION_20);
 
          assertion.getAuthnStatements().add(authnStatement);
          assertion.getAttributeStatements().add(attrStatement);
          assertion.setConditions(conditions);
 
   return assertion;
  }
  catch (Exception e)
  {
   e.printStackTrace();
  }
  return null;
 }
 
 public static class SAMLInputContainer
 {
 
  private String strIssuer;
  private String strNameID;
  private String strNameQualifier;
  private String sessionId;
  private int maxSessionTimeoutInMinutes = 15; // default is 15 minutes
 
  private Map attributes;
 
  /**
   * Returns the strIssuer.
   *
   * @return the strIssuer
   */
  public String getStrIssuer()
  {
   return strIssuer;
  }
 
  /**
   * Sets the strIssuer.
   *
   * @param strIssuer
   *            the strIssuer to set
   */
  public void setStrIssuer(String strIssuer)
  {
   this.strIssuer = strIssuer;
  }
 
  /**
   * Returns the strNameID.
   *
   * @return the strNameID
   */
  public String getStrNameID()
  {
   return strNameID;
  }
 
  /**
   * Sets the strNameID.
   *
   * @param strNameID
   *            the strNameID to set
   */
  public void setStrNameID(String strNameID)
  {
   this.strNameID = strNameID;
  }
 
  /**
   * Returns the strNameQualifier.
   *
   * @return the strNameQualifier
   */
  public String getStrNameQualifier()
  {
   return strNameQualifier;
  }
 
  /**
   * Sets the strNameQualifier.
   *
   * @param strNameQualifier
   *            the strNameQualifier to set
   */
  public void setStrNameQualifier(String strNameQualifier)
  {
   this.strNameQualifier = strNameQualifier;
  }
 
  /**
   * Sets the attributes.
   *
   * @param attributes
   *            the attributes to set
   */
  public void setAttributes(Map attributes)
  {
   this.attributes = attributes;
  }
 
  /**
   * Returns the attributes.
   *
   * @return the attributes
   */
  public Map getAttributes()
  {
   return attributes;
  }
 
  /**
   * Sets the sessionId.
   * @param sessionId the sessionId to set
   */
  public void setSessionId(String sessionId)
  {
   this.sessionId = sessionId;
  }
 
  /**
   * Returns the sessionId.
   * @return the sessionId
   */
  public String getSessionId()
  {
   return sessionId;
  }
 
  /**
   * Sets the maxSessionTimeoutInMinutes.
   * @param maxSessionTimeoutInMinutes the maxSessionTimeoutInMinutes to set
   */
  public void setMaxSessionTimeoutInMinutes(int maxSessionTimeoutInMinutes)
  {
   this.maxSessionTimeoutInMinutes = maxSessionTimeoutInMinutes;
  }
 
  /**
   * Returns the maxSessionTimeoutInMinutes.
   * @return the maxSessionTimeoutInMinutes
   */
  public int getMaxSessionTimeoutInMinutes()
  {
   return maxSessionTimeoutInMinutes;
  }
 
 }
 
}

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