CspParameters cp = new CspParameters();            
            cp.KeyContainerName = containerName;            
            cp.ProviderType = 75;
            cp.Flags = CspProviderFlags.NoPrompt;

            if (!string.IsNullOrEmpty(psw))
            {
                SecureString sec_psw = new SecureString();
                foreach (char ch in psw)
                {
                    sec_psw.AppendChar(ch);
                }
                cp.KeyPassword = sec_psw;
            }

            Gost3410CryptoServiceProvider.UseMachineKeyStore = true;

            try
            {
                Gost3410CryptoServiceProvider gost = new Gost3410CryptoServiceProvider(cp);
                // Запоминаем сертификат подписчика
                X509Certificate2 Certificate = gost.ContainerCertificate;
                // Открываем ключ подписи.            
                AsymmetricAlgorithm _SecureKey = Certificate.PrivateKey;
....