Due to the popularity of my prior posts on processing SAML using OpenSAML I put together this code that shows a more real-world-example of how you would setup an HttpServlet to sit and listen for SAML Responses that are posted to it.  Then it just shows what you might do with the Response to get what you need out of it.  Again, I'm just verifying the Signature on the Response, Decrypting the Assertion and then looping through the Attribute nodes to look at the name/value pairs.  There are other things that you might want to do such as receiving the signing-key from the Response itself (if it's being sent), or verifying a Signature on the Assertion if that's what's being signed.  The trouble I've found with SAML implementations is that the spec is consistent, but how people use it isn't, so you'll undoubtedly need to tweak something depending on what your requirements are, but this code should get you started.

1 import java.io.PrintWriter;  2 import java.io.IOException;  3 import java.io.File;  4 import java.io.FileInputStream;  5 import java.io.InputStream;  6   7 import java.util.List;  8   9 import java.security.KeyFactory; 10 import java.security.KeyStore; 11 import java.security.PublicKey; 12 import java.security.cert.CertificateFactory; 13 import java.security.cert.X509Certificate; 14 import java.security.interfaces.RSAPrivateKey; 15 import java.security.spec.X509EncodedKeySpec; 16  17 import javax.servlet.ServletException; 18 import javax.servlet.http.HttpServlet; 19 import javax.servlet.http.HttpServletRequest; 20 import javax.servlet.http.HttpServletResponse; 21  22 import org.opensaml.common.binding.BasicSAMLMessageContext; 23 import org.opensaml.saml2.binding.decoding.HTTPPostDecoder; 24 import org.opensaml.ws.message.MessageContext; 25 import org.opensaml.ws.transport.http.HttpServletRequestAdapter; 26 import org.opensaml.saml2.core.Assertion; 27 import org.opensaml.saml2.core.Attribute; 28 import org.opensaml.saml2.core.AttributeStatement; 29 import org.opensaml.saml2.core.Response; 30 import org.opensaml.saml2.encryption.Decrypter; 31 import org.opensaml.xml.XMLObject; 32 import org.opensaml.xml.encryption.DecryptionException; 33 import org.opensaml.xml.encryption.InlineEncryptedKeyResolver; 34 import org.opensaml.xml.security.keyinfo.StaticKeyInfoCredentialResolver; 35 import org.opensaml.xml.security.x509.BasicX509Credential; 36 import org.opensaml.xml.signature.Signature; 37 import org.opensaml.xml.signature.SignatureValidator; 38 import org.opensaml.xml.validation.ValidationException; 39  40 /** 41  * @author kevnls 42  * If you use this code as a base for your implementation please leave this comment intact. 43  * You should add your own name in addition. 44  */ 45  46 public class ProcessSAML extends HttpServlet { 47     48     /**  49      * Processes requests for both HTTP GET and POST methods. 50      * @param request servlet request 51      * @param response servlet response 52      * @throws ServletException if a servlet-specific error occurs 53      * @throws IOException if an I/O error occurs 54      */ 55  56     protected void processRequest(HttpServletRequest request, HttpServletResponse response) 57     throws ServletException, IOException { 58  59         response.setContentType("text/html;charset=UTF-8"); 60         PrintWriter out = response.getWriter(); 61  62         File signatureVerificationPublicKeyFile = new File("C:\\Documents and Settings\\kevnls\\My Documents\\NetBeansProjects\\SAMLReceiver\\files\\IdPSigningCert.cer"); 63         File decryptionPrivateKeyFile = new File("C:\\Documents and Settings\\kevnls\\My Documents\\NetBeansProjects\\SAMLReceiver\\files\\SPEncryptionCert.jks"); 64         String decryptionPrivateKeyName = "pvktmp:bd5ba0e0-9718-48ea-b6e6-32cd9c852d76"; 65         String decryptionPrivateKeyPassword = "!c3c0ld"; 66  67         try 68         { 69             //bootstrap the opensaml stuff 70             org.opensaml.DefaultBootstrap.bootstrap(); 71  72             // get the message context 73             MessageContext messageContext = new BasicSAMLMessageContext(); 74             messageContext.setInboundMessageTransport(new HttpServletRequestAdapter(request)); 75             HTTPPostDecoder samlMessageDecoder = new HTTPPostDecoder(); 76             samlMessageDecoder.decode(messageContext); 77  78             // get the SAML Response 79             Response samlResponse = (Response)messageContext.getInboundMessage(); 80  81             //get the certificate from the file 82             InputStream inputStream2 = new FileInputStream(signatureVerificationPublicKeyFile); 83             CertificateFactory certificateFactory = CertificateFactory.getInstance("X.509"); 84             X509Certificate certificate = (X509Certificate)certificateFactory.generateCertificate(inputStream2); 85             inputStream2.close(); 86  87             //pull out the public key part of the certificate into a KeySpec 88             X509EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(certificate.getPublicKey().getEncoded()); 89  90             //get KeyFactory object that creates key objects, specifying RSA 91             KeyFactory keyFactory = KeyFactory.getInstance("RSA"); 92  93             //generate public key to validate signatures 94             PublicKey publicKey = keyFactory.generatePublic(publicKeySpec); 95  96             //create credentials 97             BasicX509Credential publicCredential = new BasicX509Credential(); 98  99             //add public key value100             publicCredential.setPublicKey(publicKey);101 102             //create SignatureValidator103             SignatureValidator signatureValidator = new SignatureValidator(publicCredential);104 105             //get the signature to validate from the response object106             Signature signature = samlResponse.getSignature();107 108             //try to validate109             try110             {111                 signatureValidator.validate(signature);112             }113             catch (ValidationException ve)114             {115                 out.println("Signature is not valid.");116                 out.println(ve.getMessage());117                 return;118             }119 120             //no validation exception was thrown121             out.println("Signature is valid.");122 123             //start decryption of assertion124 125             //load up a KeyStore126             KeyStore keyStore = KeyStore.getInstance("JKS");127             keyStore.load(new FileInputStream(decryptionPrivateKeyFile), decryptionPrivateKeyPassword.toCharArray());128 129             RSAPrivateKey privateKey = (RSAPrivateKey) keyStore.getKey(decryptionPrivateKeyName, decryptionPrivateKeyPassword.toCharArray());130 131             //create the credential132             BasicX509Credential decryptionCredential = new BasicX509Credential();133             decryptionCredential.setPrivateKey(privateKey);134 135             StaticKeyInfoCredentialResolver skicr = new StaticKeyInfoCredentialResolver(decryptionCredential);136 137             //create a decrypter138             Decrypter decrypter = new Decrypter(null, skicr, new InlineEncryptedKeyResolver());139 140             //decrypt the first (and only) assertion141             Assertion decryptedAssertion;142 143             try144             {145                 decryptedAssertion = decrypter.decrypt(samlResponse.getEncryptedAssertions().get(0));146             }147             catch (DecryptionException de)148             {149                 out.println("Assertion decryption failed.");150                 out.println(de.getMessage());151                 return;152             }153 154             out.println("Assertion decryption succeeded.");155 156             //loop through the nodes to get the Attributes157             //this is where you would do something with these elements158             //to tie this user with your environment159             List attributeStatements = decryptedAssertion.getAttributeStatements();160             for (int i = 0; i < attributeStatements.size(); i++)161             {162                 List attributes = attributeStatements.get(i).getAttributes();163                 for (int x = 0; x < attributes.size(); x++)164                 {165                     String strAttributeName = attributes.get(x).getDOM().getAttribute("Name");166 167                     List attributeValues = attributes.get(x).getAttributeValues();168                     for (int y = 0; y < attributeValues.size(); y++)169                     {170                         String strAttributeValue = attributeValues.get(y).getDOM().getTextContent();171                         out.println(strAttributeName + ": " + strAttributeValue + " ");172                     }173                 }174             }175         }176         catch (Exception ex)177         {178             ex.printStackTrace();179         }180 181     } 182 183     // 184     /** 185      * Handles the HTTP GET method.186      * @param request servlet request187      * @param response servlet response188      * @throws ServletException if a servlet-specific error occurs189      * @throws IOException if an I/O error occurs190      */191     @Override192     protected void doGet(HttpServletRequest request, HttpServletResponse response)193     throws ServletException, IOException {194         processRequest(request, response);195     } 196 197     /** 198      * Handles the HTTP POST method.199      * @param request servlet request200      * @param response servlet response201      * @throws ServletException if a servlet-specific error occurs202      * @throws IOException if an I/O error occurs203      */204     @Override205     protected void doPost(HttpServletRequest request, HttpServletResponse response)206     throws ServletException, IOException {207         processRequest(request, response);208     }209 210     /** 211      * Returns a short description of the servlet.212      * @return a String containing servlet description213      */214     @Override215     public String getServletInfo() {216         return "This servlet processes a SAML 2.0 Response.  It verifies the signature, " +217                 "decrypts an assertion, and parses out the data in the attribute statements.  " +218                 "If you use this code as a base for your implementation please leave the @author comment intact.  " +219                 "You should add your own name in addition.";220     }// 221 222 }

I've also got a full NetBeans project with this code posted .  I've found that NetBeans is the easiest way to get an HttpServlet running locally if you install the version with the web and app server bundled in.

Anyway, hope this is useful to someone.