SAML sample code

sample.cs

var signedXml = new SignedXml(_rawXml);
var publicKey = cert.PublicKey.Key;

var signatureElement = (XmlElement) _rawXml
    .GetElementsByTagName("Signature","http://www.w3.org/2000/09/xmldsig#")
    .First();

signedXml.LoadXml(signatureElement);

// I've tried it both ways (using the embedded key)
return signedXml.CheckSignature();

// I've tried it both ways (or providing the key)
return signedXml.CheckSignature(publicKey);