Add Reference for the KeyInfo node

[brugambwa]

Discussed in #362

^{Originally posted by brugambwa July 26, 2023}

EDIT: The first reference and the digest is calculated on the KeyInfo tag, which is added using the getKeyInfoContent. So the addReference cannot find the reference to the KeyInfo tag as it's not part of the initial XML. Is there an implementation I could use/change in the library to be able to produce the output below?

    <ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
        <ds:SignedInfo>
            <ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
            <ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256"/>
            <ds:Reference URI="#f2f98882-502f-4110-8be3-4e50716740fb">
                <ds:Transforms>
                    <ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
                </ds:Transforms>
                <ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/>
                <ds:DigestValue>Some Digest</ds:DigestValue>
            </ds:Reference>
            <ds:Reference URI="">
                <ds:Transforms>
                    <ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/>
                    <ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
                </ds:Transforms>
                <ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/>
                <ds:DigestValue>Some Digest</ds:DigestValue>
            </ds:Reference>
            <ds:Reference>
                <ds:Transforms>
                    <ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
                </ds:Transforms>
                <ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/>
                <ds:DigestValue>Some Digest</ds:DigestValue>
            </ds:Reference>
        </ds:SignedInfo>
        <ds:SignatureValue>Signature-Value</ds:SignatureValue>
        <ds:KeyInfo Id="f2f98882-502f-4110-8be3-4e50716740fb">
            <ds:KeyValue>
                <ds:RSAKeyValue>
                    <ds:Modulus>Some-Modulus String</ds:Modulus>
                    <ds:Exponent>AQAB</ds:Exponent>
                </ds:RSAKeyValue>
            </ds:KeyValue>
            <ds:X509Data>
                <ds:X509Certificate>CertificateInfo</ds:X509Certificate>
            </ds:X509Data>
        </ds:KeyInfo>
    </ds:Signature></div>