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

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

[StructLayout (LayoutKind. Sequential)] 
public struct CRYPT_SIGN_MESSAGE_PARA 
{ 
	public int cbSize; 
	public int dwMsgEncodingType; 
	public IntPtr pSigningCert;//PCCERT_CONTEXT 
	public CRYPT_ALGORITHM_IDENTIFIER HashAlgorithm;//CRYPT_ALGORITHM_IDENTIFIER 
	public IntPtr pvHashAuxInfo;//void* 
	public int cMsgCert;
	public IntPtr[] rgpMsgCert; 
	public int cMsgCrl; 
	public IntPtr rgpMsgCrl;//PCCRL_CONTEXT* 
	public int cAuthAttr; 
	public IntPtr rgAuthAttr;//PCRYPT_ATTRIBUTE 
	public int cUnauthAttr; 
	public IntPtr rgUnauthAttr;//PCRYPT_ATTRIBUTE 
	public int dwFlags; 
	public int dwInnerContentType; 
	public CRYPT_ALGORITHM_IDENTIFIER HashEncryptionAlgorithm;//CRYPT_ALGORITHM_IDENTIFIER 
	public IntPtr pvHashEncryptionAuxInfo;//void* 
}

[DllImport("crypt32.dll", SetLastError = true)]
public static extern int CryptSignMessage (
	ref CRYPT_SIGN_MESSAGE_PARA pSignPara, 
	//int fDetachedSignature, 
	bool fDetachedSignature,
	int cToBeSigned, 
	IntPtr [] rgpbToBeSigned, 
	int [] rgcbToBeSigned, 
	byte [] pbSignedBlob, 
	ref int pcbSignedBlob
);

public static void Sign(byte[] data, X509Certificate2 signingCert) 
{
	int X509_ASN_ENCODING = 0x00000001;
	int PKCS_7_ASN_ENCODING = 0x00010000;
	int MY_ENCODING_TYPE = X509_ASN_ENCODING | PKCS_7_ASN_ENCODING;

	IntPtr[] rgpbToBeSigned = new IntPtr[1];
	int[] rgcbToBeSigned = new int[1];
	CRYPT_SIGN_MESSAGE_PARA SignPara = new CRYPT_SIGN_MESSAGE_PARA();

	IntPtr buffer = Marshal.AllocCoTaskMem(Marshal.SizeOf(data[0]) * data.Length);
	Marshal.Copy(data, 0, buffer, data.Length);

	rgpbToBeSigned[0] = buffer;
	rgcbToBeSigned[0] = 1;

	SignPara.cbSize = Marshal.SizeOf(SignPara);
	SignPara.dwMsgEncodingType = MY_ENCODING_TYPE;
	SignPara.pSigningCert = signingCert.Handle;
	SignPara.HashAlgorithm.pszObjId = "1.2.643.2.2.4"; // szOID_CP_GOST_R3411_R3410
	SignPara.HashAlgorithm.Parameters.cbData = 0;
	SignPara.HashAlgorithm.Parameters.pbData = null;
	SignPara.pvHashAuxInfo = IntPtr.Zero;
	SignPara.cMsgCert = 1;
	SignPara.rgpMsgCert = null;
	SignPara.cMsgCrl = 0;
	SignPara.cAuthAttr = 0;
	SignPara.dwInnerContentType = 0;
	SignPara.cUnauthAttr = 0;
	SignPara.dwFlags = 0;
	SignPara.pvHashAuxInfo = IntPtr.Zero;
	SignPara.rgAuthAttr = IntPtr.Zero;

	int signSize = 0;
	int csm = CryptSignMessage (ref SignPara, true, 1, rgpbToBeSigned, rgcbToBeSigned, null, ref signSize);
	Console.WriteLine("data.Length: " + data.Length);
	Console.WriteLine("csm: " + csm);
}