static void Main(string[] args)
        {
            string document = Convert.ToBase64String(File.ReadAllBytes(@"D:\tmp2\GuaranteeLetter_41548_8023914_EC19228AAED8446984F00C246CA0E4D6.pdf"));
            string signature = Convert.ToBase64String(File.ReadAllBytes(@"D:\tmp2\GuaranteeLetter_41548_8023914_EC19228AAED8446984F00C246CA0E4D6.pdf.sig"));

            EnchanceSignature(document, signature);
        }

        public static string EnchanceSignature(string document, string signature)
        {
            var signedData = new CadesSignedData
            {
                ContentEncoding = CADESCOM_CONTENT_ENCODING_TYPE.CADESCOM_BASE64_TO_BINARY,
                Content = document
            };


            signedData.VerifyCades(signature, CADESCOM_CADES_TYPE.CADESCOM_CADES_BES, true);
          

            string signedDataBase64 = signedData.EnhanceCades(CADESCOM_CADES_TYPE.CADESCOM_CADES_X_LONG_TYPE_1, "http://testca.cryptopro.ru/tsp/");

          

            return signedDataBase64;
        }