dynamic signedData = new CAdESCOM.CadesSignedData();
dynamic signer = new CAdESCOM.CPSigner();
dynamic oSigningTimeAttr = new CAdESCOM.CPAttribute();
oSigningTimeAttr.Name = CAPICOM.CAPICOM_ATTRIBUTE.CAPICOM_AUTHENTICATED_ATTRIBUTE_SIGNING_TIME;
oSigningTimeAttr.Value = DateTime.Now.ToUniversalTime();
signer.AuthenticatedAttributes2.Add(oSigningTimeAttr);

X509Store store = new X509Store(StoreLocation.CurrentUser);
store.Open(OpenFlags.OpenExistingOnly | OpenFlags.ReadOnly);

dynamic oStore = new CAPICOM.Store();
oStore.Open(CAPICOM.CAPICOM_STORE_LOCATION.CAPICOM_LOCAL_MACHINE_STORE, "My", 2);
string serialNumber = "13BECCB500020001FADB";
foreach (var cert in oStore.Certificates)
{
if (cert.SerialNumber == serialNumber)
{
signer.Certificate = cert;

break;
}
}

signer.TSAAddress = "http://cryptopro.ru/tsp/";
signedData.Content = hfHASH.Value;
signedData.ContentEncoding = 0;

string signedHash = signedData.SignCades(signer, CAdESCOM.CADESCOM_CADES_TYPE.CADESCOM_CADES_X_LONG_TYPE_1);