try
     {
     CPSigner signer = new CPSignerClass();
     signer.Certificate = GetSignerCertificateBySerialNum(certSerialNum);

     CadesSignedData signedData = new CadesSignedDataClass();

     //Если я выберу здесь CADESCOM_BASE64_TO_BINARY
     //И буду передавать массив byte[] переведенный в BASE64
     //signedData.ContentEncoding = CADESCOM_CONTENT_ENCODING_TYPE.CADESCOM_BASE64_TO_BINARY;
     //Здесь ОШИБКА: неверные данные
     signedData.Content = content;
     byte[] signCades = signedData.SignCades(
                    signer,
                    CADESCOM_CADES_TYPE.CADESCOM_CADES_BES,
                    false,
                    CAPICOM_ENCODING_TYPE.CAPICOM_ENCODE_BASE64
                    );


                return signCades;
            }
            catch (Exception ex)
            {
                throw new CryptoException(GetErrorString(ex.Message));
            }

signedData.Content = content;

 private static string LongMakeCadesBesSign(string dataToSign, Certificate certObject, string oldSignature = "")
        {
            string signature = "";
            try
            {
                CPSigner oSigner = new CPSigner
                {
                    Certificate = certObject,
                    Options = CAPICOM_CERTIFICATE_INCLUDE_OPTION.CAPICOM_CERTIFICATE_INCLUDE_WHOLE_CHAIN
                };

                CadesSignedData oSignedData = new CadesSignedData
                {
                    DisplayData = CADESCOM_DISPLAY_DATA.CADESCOM_DISPLAY_DATA_CONTENT,
                    ContentEncoding = CADESCOM_CONTENT_ENCODING_TYPE.CADESCOM_BASE64_TO_BINARY
                };

                if (!string.IsNullOrEmpty(dataToSign))
                {
                    byte[] bytes = Encoding.UTF8.GetBytes(dataToSign);
                    string base64String = Convert.ToBase64String(bytes);

                    CPHashedData myHesh = new CPHashedData
                    {
                        Algorithm = (CAPICOM_HASH_ALGORITHM)CADESCOM_HASH_ALGORITHM.CADESCOM_HASH_ALGORITHM_MD5,
                        DataEncoding = CADESCOM_CONTENT_ENCODING_TYPE.CADESCOM_BASE64_TO_BINARY
                    };

                    myHesh.Hash(base64String);
                
                    try
                    {
                        signature = oSignedData.SignHash((HashedData)myHesh, oSigner, CADESCOM_CADES_TYPE.CADESCOM_CADES_BES);
                    }
                    catch (Exception err)
                    {
                        MessageBox.Show("Не удалось создать подпись из-за ошибки: " + err.Message);
                    }
                }
            }
            catch (Exception err)
            {
                MessageBox.Show("Не удалось получить доступ к криптопровайдеру: " + err.Message);
            }
            return signature;
        }