C# GPG Implementation

public class GPG
    {
        private ILog log = LogManager.GetLogger(MethodInfo.GetCurrentMethod().DeclaringType);

        private const string DEFAULT_GPG_PATH = @"C:\Program Files\GNU\GnuPG\";

        private const string DECRYPT_ARGS = @"--batch --output ""{0}"" --decrypt ""{1}""";
        private const string ENCRYPT_ARGS = @"--batch --output ""{0}"" --encrypt --recipient ""{2}"" ""{1}""";
        
        private string _gpgPath;

        public GPG()
        {                        
            _gpgPath = DEFAULT_GPG_PATH;
        }

        public string GpgPath
        {
            set { _gpgPath = value; }
        }

        public string DecryptFile(string filePath)
        {            
            string outFile; 
            if (filePath.EndsWith(".gpg"))
            {
                outFile = filePath.Remove(filePath.Length - 4, 4);
            }else
            {
                outFile = string.Format("{0}{1}", filePath, ".out");
            }
            return DecryptFile(filePath,outFile);
        }

        public string DecryptFile(string filePath, string outFile)
        {            
            string args = string.Format(DECRYPT_ARGS, outFile, filePath);
            ExecuteGPG(args);
            return outFile;
        }

        public string EncryptFile(string filePath, string userId)
        {
            string outFile = string.Format("{0}{1}", filePath, ".gpg");
            return EncryptFile(filePath, outFile, userId);
        }

        public string EncryptFile(string filePath, string outFile, string userId)
        {
            string args = string.Format(ENCRYPT_ARGS, outFile, filePath, userId);
            ExecuteGPG(args);
            return outFile;
        }

        private void ExecuteGPG(string args)
        {
            try
            {
                Process process = new Process();
                string programPath = string.Format(@"""{0}""", Path.Combine(_gpgPath, "gpg.exe"));

                if(!File.Exists(programPath))
                {
                    string error = string.Format("Invalid gpg.exe path: {0}, please set GpgPath property", programPath);
                    log.Error(error);
                    throw new Exception(error);
                }

                log.InfoFormat("Executing: {0} {1}", programPath, args);

                process.StartInfo.FileName = programPath;
                //Open as readonly
                process.StartInfo.Arguments = args;
                process.StartInfo.UseShellExecute = false;
                process.StartInfo.RedirectStandardOutput = true;
                process.StartInfo.CreateNoWindow = true;
                process.StartInfo.WorkingDirectory = _gpgPath;

                process.Start();

                StreamReader reader = process.StandardOutput;
                string output = reader.ReadToEnd();

                log.InfoFormat("Output: {0}", output);
            }
            catch (Exception ex)
            {
                log.Error("Failed to execute gpg.exe command",ex);
                throw;                
            }            
        }
    }