Confirm signature of SAML response

Question

I am trying to fulfill the following specification in order to verify the signature of the SAML response: https://www.w3.org/TR/xmldsig-core/#sec-PKCS1

Here is my workflow: I get a SAML response. I get rid of the signature envelope, I canonicalize it, I check the digest, and then check the signature. I was able to successfully calculate the SHA1 digest of the converted SAML response and verify it. However, the RSA-SHA1 signature verification still eludes me.

SAML Response includes a signature method algorithm: http://www.w3.org/2000/09/xmldsig#rsa-sha1

I have this method for verifying a signature:

public static boolean verifySignature(String signatureType, PublicKey publicKey, byte[] contentBytes, byte[] sigBytes) {
    try {
        Signature sig = Signature.getInstance(signatureType);
        sig.initVerify(publicKey);
        sig.update(contentBytes);
        return sig.verify(sigBytes);
    } catch (Exception e) {
        Logger.log(e);
        return false;
    }
}

I am doing something like this to call it:

String publicKeyStr =  "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";
PublicKey publicKey = Security.getPublicKey(publicKeyStr); // uses Certificate class
String sig = "QfAcRJM2P65JucyBpqn6j48/zd1oSLPBJ0lYI1grH5/xenwBEh0D4Eh0S1J3535OUmldpW7D+G7DW6eAT5N8TdoqUvMXuIAUpFHHDR45KZykPXJPUtli+z2rwlCCHypZWnniT/wrcQYdpp1zzNJBBtKdkaqQg0NMktPSQ/0ti+ruMI3qwfTaL9kDQ3Zyi/a2J3RCAPA0RfviLnDLlid0PthiV1NEbs0AvnguDi57fWXAILk0L1Cx20sliQckxlFQ9u4OaHeMscXdjh3SfESkM9m0Y9PppisZWTrCYzGmvDwsZTCBPD3f/ZFIit+Smgh2fi1u8/gZq0yizPyacR3Y/A==";
String newXMLToOperateOn = "<saml2:Assertion xmlns:saml2="urn:oasis:names:tc:SAML:2.0:assertion" xmlns:xs="http://www.w3.org/2001/XMLSchema" ID="_420cc1a25a3890bd5df1f4c04bd7e986" ...";

boolean sign = Security.verifySignature("SHA1withRSA", pk, newXMLToOperateOn.getBytes(), Util.base64DecodeAsBytes(sig));
// SIGN IS FALSE!!!!

newXMLToOperateOn XML SAMLResponse. , SHA1. Security.verify() , SSID OpenID, .

, XML SHA1, . E.G. verify(algo, pk, sha1Digest.getBytes(), sig.getBytes().

- , -, ? , :

   CRYPT (PAD (ASN.1 (OID, DIGEST (data))))

, . , , .

.

Answer 1

"SignedInfo" XML