var oHashedData =  cadesplugin.CreateObject("CAdESCOM.HashedData");
 oHashedData.Algorithm = 100;//CADESCOM_HASH_ALGORITHM_CP_GOST_3411
 oHashedData.SetHashValue(sHashValue); // хеш данных (в нашем случае файла)
 oSignedData.VerifyHash(oHashedData, previousSignData, CADESCOM_CADES_BES); //previousSignData - предыдущая подпись в base64
 signature = oSignedData.CoSignHash(oHashedData, oSigner, CADESCOM_CADES_BES); 

function CoSignHash(sSignedHash ) {
var cadesplugin = new ActiveXObject("cadescom.webclassfactory");

var oHashedData4 = cadesplugin.CreateObject("CAdESCOM.HashedData");
var s = "534CF6F93B1C377EC944F962EF6BF91A9694D691E45A7910B27A2BC855ABA6CB";
oHashedData4.SetHashValue(s);
var oSignedData2 = cadesplugin.CreateObject("CAdESCOM.CadesSignedData");
oSignedData2.VerifyHash(oHashedData4, sSignedHash, CADESCOM_CADES_BES);

var oStore = cadesplugin.CreateObject("CAdESCOM.Store");
oStore.Open(CAPICOM_CURRENT_USER_STORE, CAPICOM_MY_STORE,
CAPICOM_STORE_OPEN_MAXIMUM_ALLOWED);

var oSigner = cadesplugin.CreateObject("CAdESCOM.CPSigner");

var sCoSignedHash = oSignedData2.CoSignHash(oHashedData4, oSigner, CADESCOM_CADES_BES);
}