How to verify a SAML signature for HTTP-redirect binding

Question

I\'m receiving a SAML request via HTTP-redirect binding the content of the SAML request look like this

{\"SigAlg\"=>\"http://www.w3.org/2000/09/xmldsi

Answer 1

I'am trying using the above answer but don't success.

Then, read the documentation and a little time, i have sucess to validate signature with Java and the fast answer is:

final String samlRequest = request.getParameter("SAMLRequest");
final String relayState = request.getParameter("RelayState");
final String sigAlg = request.getParameter("SigAlg");
final String signature = request.getParameter("Signature");

FileInputStream fis = new FileInputStream(new File("path-to-service-provider-x509-certificate"));

CertificateFactory cf = CertificateFactory.getInstance("X.509");
Certificate cert = cf.generateCertificate(fis);

// ps: java.net.URLEncoder;
String query = "SAMLRequest=" + URLEncoder.encode(samlRequest, "UTF-8");
query += "&RelayState=" +URLEncoder.encode(relayState, "UTF-8");
query += "&SigAlg=" + URLEncoder.encode(sigAlg, "UTF-8");

// ps: org.opensaml.xml.util.Base64
byte[] signatureBytes = Base64.decode(signature);

org.apache.xml.security.Init.init();
Signature sig = Signature.getInstance("SHA1withRSA"); // or other alg (i, e: SHA256WithRSA or others)
sig.initVerify(cert.getPublicKey());
sig.update(query.getBytes());
Boolean valid = sig.verify(signatureBytes);