Base64Converter.cs

using System;
using System.Text;

namespace AdrianoKerber.Converter
{
    public static class Base64Converter
    {
        public static string FromStringToBase64(string stringValue)
        {
            if (string.IsNullOrWhiteSpace(stringValue))
                return null;

            byte[] stringAsByteArray = Encoding.ASCII.GetBytes(stringValue);
            string base64Value = Convert.ToBase64String(stringAsByteArray);

            return base64Value;
        }

        public static string FromBase64ToString(string base64Value)
        {
            if (string.IsNullOrWhiteSpace(base64Value))
                return null;

            byte[] base64AsByteArray = Convert.FromBase64String(base64Value);
            string plainTextString = Encoding.ASCII.GetString(base64AsByteArray);

            return plainTextString;
        }
    }
}