using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

    }

    using System;

using System.Threading.Tasks;

using SMBC.CM.Interface.File;

using SMBC.FWCM.Command;

using System.Security.Cryptography.Xml;

using System.Xml;

using System.Security.Cryptography.X509Certificates;

using SMBC.CM.Model.Enums;

using System.Security.Cryptography;

using System.IO;

using SMBC.CM.Model;

using SMBC.CM.Model.File.Response;

​

namespace SMBC.CM.Service.File

{

    public class VerifyDocumentService : BaseCommand<bool>, IVerifyDocumentService

    {

        private XmlDocument _xmlDocument;

        private readonly string _digestValue;

        private readonly HashAlgorithmEnum _hashAlgorithm;

        private readonly Stream _signedStream;

        private readonly X509Certificate2 _publicKey;

        private const string SIGNATURE = "Signature";

        public VerifyDocumentService(XmlDocument xmlDocument, X509Certificate2 publicKey, string digestValue, HashAlgorithmEnum hashAlgorithm)

        {

            _xmlDocument = xmlDocument;

            _digestValue = digestValue;

            _hashAlgorithm = hashAlgorithm;

            _publicKey = publicKey;

        }

        public VerifyDocumentService(Stream signedStream, X509Certificate2 publicKey, string digestValue, HashAlgorithmEnum hashAlgorithm)

        {

            _signedStream = signedStream;

            _digestValue = digestValue;

            _hashAlgorithm = hashAlgorithm;

            _publicKey = publicKey;

        }

        public void ExecuteCommandTest()

        {

            ExecuteTest();

        }

        protected override Task ExecuteAsyncCommandProcess()

        {

            throw new NotImplementedException();

        }

        protected override void ExecuteCommandProcess()

        {

            #region Load signature

            if (_signedStream != null)

            {

                _signedStream.Position = 0;

                _xmlDocument = new XmlDocument();

                _xmlDocument.Load(new XmlTextReader(_signedStream));

            }

​

            XmlNodeList nl = _xmlDocument.GetElementsByTagName(SIGNATURE, "http://www.w3.org/2000/09/xmldsig#");

​

            if (nl.Count == 0)

                throw new Exception("Cannot find Signature element");

            if (_publicKey == null)

                throw new Exception("Correct certificate required - Required for name/serial checking on signatue file, but was not found/loaded");

​

            string certIssuerName = _publicKey.Issuer;

            string certSerialNum = _publicKey.SerialNumber;

​

            string sigFileIssuerName = _xmlDocument.GetElementsByTagName("X509IssuerName", "http://www.w3.org/2000/09/xmldsig#").Item(0).InnerText;

            string sigFileSerialNum = _xmlDocument.GetElementsByTagName("X509SerialNumber", "http://www.w3.org/2000/09/xmldsig#").Item(0).InnerText;

​

            if (certIssuerName != sigFileIssuerName)

                throw new Exception($"WARNING: given Certificate issuer name [{certIssuerName}] does not match with Signature file's issuer name: [{sigFileIssuerName}]");

​

            var serialNum = GetSerialNum(certIssuerName, certSerialNum);

            if (serialNum != sigFileSerialNum)

                throw new Exception($"WARNING: given Certificate serial number [{serialNum}] does not match with Signature file's serial Number: [{sigFileSerialNum }]");

​

            SignedXml signedXml = new SignedXml(_xmlDocument);

            XmlNodeList nodeList = _xmlDocument.GetElementsByTagName(SIGNATURE);

            signedXml.LoadXml((XmlElement)nodeList[0]);

            #endregion Load signature

​

            #region Verify digestValue ex:compare file content doesn't get change

            var digestValueToVerify = Utility.Functions.Base64Encode(((Reference)signedXml.SignedInfo.References[0]).DigestValue);

            if (_digestValue != digestValueToVerify)

                throw new Exception("Invalid digest value!");

            #endregion Verify digestValue ex:compare file content doesn't get change

​

            #region Hash signedInfo Stream by sha256Bytes

            HashStreamResponse signatureHash;

            var xmlString = signedXml.SignedInfo.GetXml().OuterXml;

​

            using (var svc = new HashService(Utility.Functions.StringXml2Stream(xmlString), _hashAlgorithm))

            {

                svc.Initialize();

                svc.Execute();

                signatureHash = svc.Result;

            }

            #endregion Hash signedInfo Stream by sha256Bytes

​

            #region Verify signature

            RSACryptoServiceProvider csp = (RSACryptoServiceProvider)_publicKey.PublicKey.Key;

            var halg = Dictionaries.HashAlgorithmDictionary(_hashAlgorithm);

            Result = csp.VerifyData(signatureHash.Bytes, halg, signedXml.Signature.SignatureValue);

            #endregion Verify signature 

        }

        private string GetSerialNum(string certIssuerName, string certSerialNum)

        {

            KeyInfoX509Data x509DataType = new KeyInfoX509Data();

            x509DataType.AddIssuerSerial(_publicKey.Issuer, _publicKey.SerialNumber);

            return ((X509IssuerSerial)x509DataType.IssuerSerials[0]).SerialNumber;

        }

    }

}

}