Verifying XML digital signature with Chilkat

In the previous post, I showed how to verify XML digital signature using SignedXml object from namespace System.Security.Cryptography.Xml. However that method could only verify signatures signed by .Net and fails to verify a valid signature signed via front end using Javascript or a valid signature with custom transform nodes.

Chilkat is not a free library but it provides the ability to verify XML digital signature with any custom transformations.

Below is the same method with using Chilkat

        public bool VerifyXmlDSigValue(string value)
        {
            var xmlDoc = new XmlDocument();
            xmlDoc.LoadXml(value);
            var verifier = new Chilkat.XmlDSig();

            var success = verifier.LoadSignature(xmlDoc.InnerXml);

            if (!success)
                throw new Exception($"Chilkat error: {verifier.LastErrorText}");

            var numSig = verifier.NumSignatures;

            if (numSig == 0)
                throw new InvalidOperationException("No signatures found");

            for (int i = 0; i < numSig; i++)
            {
                verifier.Selector = i;
                var verified = verifier.VerifySignature(true);

                if (!verified)
                    return false;
            }

            return true;
        }