diff --git a/lib/samlp.js b/lib/samlp.js
index 63795aa..1895448 100644
--- a/lib/samlp.js
+++ b/lib/samlp.js
@@ -64,21 +64,47 @@ function buildSamlResponse(options) {
       idAttribute: 'ID'
     });
 
+    var transforms = [];
+
+    if (!options.signAssertion) {
+      transforms.push("http://www.w3.org/2000/09/xmldsig#enveloped-signature");
+    }
+
+    transforms.push("http://www.w3.org/2001/10/xml-exc-c14n#");
+
     sig.addReference(
       "//*[local-name(.)='Response' and namespace-uri(.)='urn:oasis:names:tc:SAML:2.0:protocol']",
-      ["http://www.w3.org/2000/09/xmldsig#enveloped-signature", "http://www.w3.org/2001/10/xml-exc-c14n#"],
+      transforms,
       algorithms.digest[options.digestAlgorithm]);
 
     sig.signingKey = options.key;
 
     var pem = encoders.removeHeaders(options.cert);
+
+    var dsPrefix = '';
+    if (options.addDsPrefix) {
+      dsPrefix = 'ds:';
+    }
+
     sig.keyInfoProvider = {
       getKeyInfo: function () {
-        return "<X509Data><X509Certificate>" + pem + "</X509Certificate></X509Data>";
+        return "<" + dsPrefix + "X509Data><" + dsPrefix + "X509Certificate>" + pem + "</" + dsPrefix + "X509Certificate></" + dsPrefix + "X509Data>";
       }
     };
 
-    sig.computeSignature(cannonicalized);
+    var sigOpts = {
+      location: {
+        reference: options.xpathToNodeBeforeSignature || "//*[local-name(.)='Issuer']",
+        action: 'after'
+      }
+    }
+
+    if (options.addDsPrefix) {
+      sigOpts.prefix = 'ds';
+    }
+
+    sig.computeSignature(cannonicalized, sigOpts);
+
     SAMLResponse = sig.getSignedXml();
   }
 
@@ -114,7 +140,8 @@ function getSamlResponse(options, user, callback) {
     authnContextClassRef: options.authnContextClassRef,
     encryptionPublicKey:  options.encryptionPublicKey,
     encryptionCert:       options.encryptionCert,
-    sessionIndex:         options.sessionIndex
+    sessionIndex:         options.sessionIndex,
+    addDsPrefix:          options.addDsPrefix
   }, function (err, signedAssertion) {
     if (err) return callback(err);