Customize Signing

Signature.java

    @Override

    public Assertion doSetSignature(Assertion assertion, String signatureAlgorithm, X509Credential cred) throws IdentityException {

        try {
            //override the credentials with our desired one
            cred = getRequiredCredentials();
            Signature signature = (Signature) buildXMLObject(Signature.DEFAULT_ELEMENT_NAME);
            signature.setSigningCredential(cred);
            signature.setSignatureAlgorithm(signatureAlgorithm);
            signature.setCanonicalizationAlgorithm(Canonicalizer.ALGO_ID_C14N_EXCL_OMIT_COMMENTS);

            try {
                KeyInfo keyInfo = (KeyInfo) buildXMLObject(KeyInfo.DEFAULT_ELEMENT_NAME);
                X509Data data = (X509Data) buildXMLObject(X509Data.DEFAULT_ELEMENT_NAME);
                X509Certificate cert = (X509Certificate) buildXMLObject(X509Certificate.DEFAULT_ELEMENT_NAME);

                String value = org.apache.xml.security.utils.Base64.encode(cred
                        .getEntityCertificate().getEncoded());
                cert.setValue(value);
                data.getX509Certificates().add(cert);
                keyInfo.getX509Datas().add(data);
                signature.setKeyInfo(keyInfo);
            } catch (CertificateEncodingException e) {
                throw new IdentityException("errorGettingCert");
            }

            assertion.setSignature(signature);

            List<Signature> signatureList = new ArrayList<Signature>();
            signatureList.add(signature);

            // Marshall and Sign
            MarshallerFactory marshallerFactory = org.opensaml.xml.Configuration
                    .getMarshallerFactory();
            Marshaller marshaller = marshallerFactory.getMarshaller(assertion);
            marshaller.marshall(assertion);

            org.apache.xml.security.Init.init();
            Signer.signObjects(signatureList);

            return assertion;
        } catch (Exception e) {
            throw new IdentityException("Error while signing the SAML Response message.", e);
        }