Base64Url.cs

using System;
 
namespace Waher.Content
{
    public static class Base64Url
    {
        public static byte[] Decode(string Base64Url)
        {
            int c = Base64Url.Length;
            int i = c & 3;
 
            Base64Url = Base64Url.Replace('-', '+'); // 62nd char of encoding
            Base64Url = Base64Url.Replace('_', '/'); // 63rd char of encoding
 
            switch (i)
            {
                case 1:
                    Base64Url += "A==";
                    break;
 
                case 2:
                    Base64Url += "==";
                    break;
 
                case 3:
                    Base64Url += "=";
                    break;
            }
 
            return Convert.FromBase64String(Base64Url);
        }
 
        public static string Encode(byte[] Data)
        {
            string s = Convert.ToBase64String(Data);
            int c = Data.Length;
            int i = c % 3;
 
            if (i == 1)
                s = s.Substring(0, s.Length - 2);
            else if (i == 2)
                s = s.Substring(0, s.Length - 1);
 
            s = s.Replace('+', '-'); // 62nd char of encoding
            s = s.Replace('/', '_'); // 63rd char of encoding
 
            return s;
        }
    }
}