using System;
using System.ComponentModel;
using System.Runtime.InteropServices;
using System.Security.Cryptography.X509Certificates;

namespace Test1
{
  class Program
  {

    [StructLayout(LayoutKind.Sequential)]
    struct CRYPTOAPI_BLOB
    {
      public Int32 cbData;
      public IntPtr pbData;
    }

    [StructLayout(LayoutKind.Sequential)]
    struct CRYPT_ALGORITHM_IDENTIFIER
    {
      [MarshalAs(UnmanagedType.LPStr)]
      public String pszObjId;
      public CRYPTOAPI_BLOB Parameters;
    }

    [StructLayout(LayoutKind.Sequential)]
    struct CRYPT_SIGN_MESSAGE_PARA
    {
      public Int32 cbSize;
      public Int32 dwMsgEncodingType;
      public IntPtr pSigningCert;
      public CRYPT_ALGORITHM_IDENTIFIER HashAlgorithm;
      public IntPtr pvHashAuxInfo;
      public Int32 cMsgCert;
      public IntPtr rgpMsgCert;
      public Int32 cMsgCrl;
      public IntPtr rgpMsgCrl;
      public Int32 cAuthAttr;
      public IntPtr rgAuthAttr;
      public Int32 cUnauthAttr;
      public IntPtr rgUnauthAttr;
      public Int32 dwFlags;
      public Int32 dwInnerContentType;
    }

    [DllImport("Crypt32.dll", SetLastError = true)]
    static extern Boolean CryptSignMessage(
      ref CRYPT_SIGN_MESSAGE_PARA pSignPara,
      Boolean fDetachedSignature,
      Int32 cToBeSigned,
      IntPtr[] rgpbToBeSigned,
      Int32[] rgcbToBeSigned,
      Byte[] pbSignedBlob,
      ref Int32 pcbSignedBlob
    );

    const Int32 X509_ASN_ENCODING = 0x00000001;
    const Int32 PKCS_7_ASN_ENCODING = 0x00010000;
    const string szOID_CP_GOST_R3411 = "1.2.643.2.2.9";

    //Отпечаток известного нам сертификата
    const string CertThumbprint = "D55E8BC8037937D1A836F8A0524E56B1C49AD281";
    const string StringForSign = "Some Data"; //Данные для подписи
    static void Main()
    {
      X509Store MyStore = new X509Store(StoreLocation.CurrentUser);
      MyStore.Open(OpenFlags.ReadOnly);
      try
      {
        foreach (X509Certificate2 MyCert in MyStore.Certificates)
        {
          if (MyCert.Thumbprint == CertThumbprint) //Нашли нужный
          {
            CRYPT_SIGN_MESSAGE_PARA MySignContext = new CRYPT_SIGN_MESSAGE_PARA();
            MySignContext.cbSize = Marshal.SizeOf(typeof(CRYPT_SIGN_MESSAGE_PARA));
            MySignContext.dwMsgEncodingType = X509_ASN_ENCODING | PKCS_7_ASN_ENCODING;
            MySignContext.pSigningCert = MyCert.Handle;
            MySignContext.HashAlgorithm.pszObjId = szOID_CP_GOST_R3411;
            IntPtr[] BuffToSign = new IntPtr[1] { Marshal.StringToHGlobalAnsi(StringForSign) };
            try
            {
              int SignedLen = 4096;
              byte[] Result = new byte[SignedLen];
              int[] bufferLen = new int[1] { StringForSign.Length };
              if (CryptSignMessage(ref MySignContext, true, 1, BuffToSign, bufferLen, Result, ref SignedLen))
              {
                Array.Resize(ref Result, SignedLen);
                for (int i = 0; i < Result.Length; i++)
                {
                  Console.Write("{0:X2} ", Result[i]);
                  if ((i+1) % 26 == 0)
                    Console.WriteLine();
                }
                Console.Write("\nLength = {0}", Result.Length);
                Console.Write("\nPress any key to exit:  ");
                Console.ReadKey();
              }
              else
                throw new Win32Exception(Marshal.GetLastWin32Error());
            }
            finally
            {
              Marshal.FreeHGlobal(BuffToSign[0]);
            }
            break;
          }
        }
      }
      finally
      {
        MyStore.Close();
      }
    }
  }
}

  int SignedLen = 4096;
              byte[] Result = new byte[SignedLen]; 

function TestClick() {
  var CADESCOM_HASH_ALGORITHM_CP_GOST_3411 = 100;
  var CADESCOM_BASE64_TO_BINARY = 1;
  var CAPICOM_CERTIFICATE_FIND_SHA1_HASH = 0;
  var CADES_BES = 1;
  var CADESCOM_CADES_DEFAULT = 0;

  var oSigner = CreateObject("CAdESCOM.CPSigner");
  oSigner.Options = 0;
  var oSignedData = CreateObject("CAdESCOM.CadesSignedData");
  oSignedData.Content = "Some Data";
  var sSignedData = oSignedData.SignCades(oSigner, CADES_BES);
  document.getElementById("EpText").value = sSignedData;
}