function InitializeHashedData(data, hashAlg) {
    var oHashedData = cadesplugin.CreateObject("CAdESCOM.HashedData");
    oHashedData.Algorithm = hashAlg;
    oHashedData.Hash(data);
    oHashedData.SetHashValue(oHashedData.Value);
    return oHashedData;
}

function CreateSignature(oCertificate, oHashedData) {
    var oRawSignature = cadesplugin.CreateObject("CAdESCOM.RawSignature");
    try {
        var sRawSignature = oRawSignature.SignHash(oHashedData, oCertificate);
    } catch (err) {
        alert("Failed to create signature. Error: " + GetErrorMessage(err));
        return;
    }
    return sRawSignature;
}

//...
    CADESCOM_HASH_ALGORITHM_CP_GOST_3411 = 100;
    hashAlg = CADESCOM_HASH_ALGORITHM_CP_GOST_3411;
    var oHashedData = InitializeHashedData(dataToSign, hashAlg);
    var RawSignature = CreateSignature(certObject, oHashedData);
//...

EAC6029553DD3C71D518E94F3247898012B234FBC1414D0938DF638E5E5EFE29FB7BFCE75DA35BB5B4F631BFEC8A89FEF4D7D372FADD21D759DAEE0F079EC3D0

String HashAlg = "Gost3411";
//...
Gost3410CryptoServiceProvider myProvider = (Gost3410CryptoServiceProvider) certificate.PublicKey.Key)
return myProvider.VerifyData(data, hashAlg, signature); // return false

var sRawSignature = oRawSignature.SignHash(oHashedData, oCertificate);