C# - SHA512 String Hash

private string HashString(string InputString)
        {
            StringBuilder ReturnString = new StringBuilder();
            SHA512Managed SHA512Mang = new SHA512Managed();

            try
            {
                if (string.IsNullOrEmpty(InputString))
                    return string.Empty;

                byte[] byteData = SHA512Mang.ComputeHash(System.Text.Encoding.ASCII.GetBytes(InputString));

                for (int i = 0; i < byteData.Length; i++)
                {
                    ReturnString.Append(byteData[i].ToString("x2"));
                }

                return ReturnString.ToString();
            }
            catch (Exception ex)
            {
                return string.Empty;
            }
            finally
            {
                SHA512Mang.Dispose();
            }

        }