using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Cryptography;
using System.Security.Cryptography.Xml;
using System.Security.Cryptography.X509Certificates;
using System.Xml;
using System.Security;
using System.Reflection;
using System.IO;
using System.Runtime.InteropServices;
using System.Net;

using CryptoPro.Sharpei;
using CryptoPro.Sharpei.Xml;

namespace Samples.Xml.cs
{
  class SignSmevRequest
  {
    private const string CallerInformationSystemSignatureTag = "CallerInformationSystemSignature";
    private const string CallerInformationSystemSignatureTagNamespace = "urn://x-artefacts-smev-gov-ru/services/message-exchange/types/1.2";
    private const string AckTargetMessageTag = "ns1:AckTargetMessage";
    private const string MessagePrimaryContentTag = "basic:MessagePrimaryContent";
    private const string PersonalSignatureTag = "PersonalSignature";
    private const string PersonalSignatureTagNamespace = "urn://x-artefacts-smev-gov-ru/services/message-exchange/types/1.2";
    private const string SenderProvidedRequestDataTag = "tns:SenderProvidedRequestData";

    [STAThread]
    static void Main(string[] args)
    {
       if (args.Length < 2)
      {
        Console.WriteLine("<doc_to_sign> <signed_doc>");
        return;
      }
       X509Certificate2Collection certs = null;
       X509Store certStore = new X509Store(StoreLocation.CurrentUser);
       certStore.Open(OpenFlags.ReadOnly);   
       // "01020389ef09"  - Серийный номер сертификата ЭЦП   
       certs = certStore.Certificates.Find(X509FindType.FindBySerialNumber, "01020389ef09", false);
       SignXmlFile2(args[0], args[1], certs[0]); 
     }

    static XmlElement SignElement2(string xml, X509Certificate2 Certificate, string signUri)
    {
      XmlDocument xmlObj = new XmlDocument();
      xmlObj.PreserveWhitespace = true;
      XmlDeclaration xmldecl;
      xmldecl = xmlObj.CreateXmlDeclaration("1.0", "UTF-8", null);
      xmlObj.LoadXml(xml);

      SignedXml signedXml = new SignedXml(xmlObj);

      signedXml.SigningKey = Certificate.PrivateKey;
      Reference reference = new Reference();
      reference.Uri = signUri.Length > 0 ? "#" + signUri : "";
#pragma warning disable 612
       signedXml.SignedInfo.SignatureMethod = CryptoPro.Sharpei.Xml.CPSignedXml.XmlDsigGost3410_2012_256Url;
#pragma warning restore 612

      XmlDsigExcC14NTransform c14 = new XmlDsigExcC14NTransform();
      signedXml.SignedInfo.CanonicalizationMethod = SignedXml.XmlDsigExcC14NTransformUrl;

      CryptoPro.Sharpei.Xml.XmlDsigSmevTransform smev = new CryptoPro.Sharpei.Xml.XmlDsigSmevTransform();
      //signedXml.SafeCanonicalizationMethods.Add("urn://smev-gov-ru/xmldsig/transform");
      reference.AddTransform(new XmlDsigEnvelopedSignatureTransform());
      reference.AddTransform(c14);
      reference.AddTransform(smev);      
      signedXml.AddReference(reference);
#pragma warning disable 612
        signedXml.SignedInfo.SignatureMethod = CryptoPro.Sharpei.Xml.CPSignedXml.XmlDsigGost3410_2012_256Url;
#pragma warning restore 612
      signedXml.KeyInfo = new KeyInfo();
      signedXml.KeyInfo.AddClause(new KeyInfoX509Data(Certificate));
      signedXml.Signature.Id = "SignId_" + Certificate.SerialNumber;
      signedXml.ComputeSignature();
      return signedXml.GetXml();
    }

    static void SignXmlFile2(string FileName, string SignedFileName, X509Certificate2 Certificate)
    {
      XmlDocument doc = new XmlDocument();
      doc.Load(new XmlTextReader(FileName));
      doc.PreserveWhitespace = true;

      XmlElement xNode2Change;
      XmlNodeList nlElmnts;
      XmlElement xNodeToSign;
      XmlElement xSign;
      XmlNode xInsert;
      XmlElement xMain;
      string sUri;

      nlElmnts = doc.GetElementsByTagName(MessagePrimaryContentTag);
      if (nlElmnts.Count == 1)
      {
        xNode2Change = (XmlElement)nlElmnts[0];
        if (xNode2Change.ChildNodes.Count != 1) throw new XmlException(string.Format("Количество потомков не равно 1 у {0}", MessagePrimaryContentTag));

        if (xNode2Change.GetAttribute("xmlns").Length > 0)
        {
          xNode2Change.Prefix = "mpc";
          xNode2Change.SetAttribute("xmlns:" + xNode2Change.Prefix, xNode2Change.GetAttribute("xmlns"));
          xNode2Change.Attributes.Remove(xNode2Change.Attributes[0]);
        }

        xMain = xNode2Change;
        // Любой дочерний узел у MessagePrimaryContent
        xNodeToSign = (XmlElement)xMain.ChildNodes[0];
        sUri = xNodeToSign.GetAttribute("Id");

        xSign = SignElement2(doc.OuterXml, Certificate, sUri);

        nlElmnts = doc.GetElementsByTagName(PersonalSignatureTag, PersonalSignatureTagNamespace);
        if (nlElmnts.Count == 1)
        {
          xInsert = nlElmnts[0];
          xInsert.RemoveAll();
        }
        else if (nlElmnts.Count == 0)
        {
          xInsert = doc.CreateNode(XmlNodeType.Element, PersonalSignatureTag, PersonalSignatureTagNamespace);
          xNodeToSign.ParentNode.ParentNode.InsertAfter(xInsert, xMain);
        }
        else throw new XmlException(string.Format("Количество потомков не равно 1 у {0}", PersonalSignatureTag));

        xInsert.AppendChild(doc.ImportNode(xSign, true));
      }

      // CallerInformationSystemSignature
      nlElmnts = doc.GetElementsByTagName(SenderProvidedRequestDataTag);
      if (nlElmnts.Count != 1)
        nlElmnts = doc.GetElementsByTagName(AckTargetMessageTag);
      if (nlElmnts.Count != 1) throw new XmlException(string.Format("Количество потомков не равно 1 у {0}", SenderProvidedRequestDataTag));
      xNodeToSign = (XmlElement)nlElmnts[0];

      sUri = xNodeToSign.GetAttribute("Id");

      xSign = SignElement2(doc.OuterXml, Certificate, sUri);

      nlElmnts = doc.GetElementsByTagName(CallerInformationSystemSignatureTag, CallerInformationSystemSignatureTagNamespace);
      if (nlElmnts.Count == 1)
      {
        xInsert = nlElmnts[0];
        xInsert.RemoveAll();
        xInsert.ParentNode.RemoveChild(xInsert);
      }
      else if (nlElmnts.Count == 0) xInsert = doc.CreateNode(XmlNodeType.Element, CallerInformationSystemSignatureTag, CallerInformationSystemSignatureTagNamespace);
      else throw new XmlException(string.Format("Количество потомков не равно 1 у {0}", CallerInformationSystemSignatureTag));

      xInsert.AppendChild(doc.ImportNode(xSign, true));
      xNodeToSign.ParentNode.AppendChild(xInsert);

      if (doc.FirstChild is XmlDeclaration)
      {
        doc.RemoveChild(doc.FirstChild);
      }
      // Сохраняем подписанный документ в файл.
      using (XmlTextWriter xmltw = new XmlTextWriter(SignedFileName, new UTF8Encoding(false)))
      {
        doc.WriteTo(xmltw);
      }
    } 

}

<?xml version="1.0" encoding="UTF-8"?><S:Envelope xmlns:S="http://schemas.xmlsoap.org/soap/envelope/" xmlns:basic="urn://x-artefacts-smev-gov-ru/services/message-exchange/types/basic/1.2" xmlns:tns="urn://x-artefacts-smev-gov-ru/services/message-exchange/types/1.2">
    <S:Body>
        <tns:SendRequestRequest>
            <tns:SenderProvidedRequestData Id="SIGNED_BY_CALLER">
                <tns:MessageID>0b588a68-643e-4a27-ae2a-1665f74fcefc</tns:MessageID>
                <basic:MessagePrimaryContent>
                    <req:ImportChargesRequest xmlns:org="http://roskazna.ru/gisgmp/xsd/Organization/2.1.0" xmlns:com="http://roskazna.ru/gisgmp/xsd/Common/2.1.0" xmlns:chg="http://roskazna.ru/gisgmp/xsd/Charge/2.1.0" xmlns:pkg="http://roskazna.ru/gisgmp/xsd/Package/2.1.0" xmlns:req="urn://roskazna.ru/gisgmp/xsd/services/import-charges/2.1.0" xmlns:rfd="http://roskazna.ru/gisgmp/xsd/Refund/2.1.0" xmlns:pmnt="http://roskazna.ru/gisgmp/xsd/Payment/2.1.0" Id="G_fce0c544-b08d-44bc-83d8-738f10e9d069" timestamp="2019-03-13T15:27:53.045+03:00" senderIdentifier="3eacb7" senderRole="1">
	<pkg:ChargesPackage>
		<pkg:ImportedCharge Id="I_54a59db2-3845-4915-8770-dd95394aadb4" originatorId="3eb5fa" supplierBillID="32116102414550976332" billDate="2019-03-13T14:06:30.313+03:00" totalAmount="500000" purpose="Oplata" kbk="32111301031016000130" oktmo="45348000">
			<chg:Payee name="Reestr" inn="7705401341" kpp="770542151" ogrn="7723819340452">
				<com:OrgAccount accountNumber="40101810045250010041">
					<com:Bank name="Gu Bank" bik="044525000"/>
				</com:OrgAccount>
			</chg:Payee>
                        <chg:ChangeStatus meaning="1"/>
			<chg:Payer payerIdentifier="1220000000007712579832" payerName="test payer"/>
			<chg:BudgetIndex status="01" paytReason="0" taxPeriod="0" taxDocNumber="0" taxDocDate="0"/>
		</pkg:ImportedCharge>
	</pkg:ChargesPackage>
</req:ImportChargesRequest>
                </basic:MessagePrimaryContent>
              </tns:SenderProvidedRequestData>
        </tns:SendRequestRequest>
    </S:Body>
</S:Envelope>