javascript encode64 decode64

var keyStr = "ABCDEFGHIJKLMNOP" +"QRSTUVWXYZabcdef" +"ghijklmnopqrstuv" +"wxyz0123456789+/" +"=";

 function encode64(input)
    {
        input = escape(input);
        var output = "";
        var chr1, chr2, chr3 = "";
        var enc1, enc2, enc3, enc4 = "";
        var i = 0;
        do
        {
            chr1 = input.charCodeAt(i++);
            chr2 = input.charCodeAt(i++);
            chr3 = input.charCodeAt(i++);

            enc1 = chr1 >> 2;
            enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
            enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
            enc4 = chr3 & 63;

            if (isNaN(chr2))
            {
                enc3 = enc4 = 64;
            }
            else if (isNaN(chr3))
            {
                enc4 = 64;
            }

            output = output + keyStr.charAt(enc1) + keyStr.charAt(enc2) + keyStr.charAt(enc3) +
            keyStr.charAt(enc4);
            chr1 = chr2 = chr3 = "";
            enc1 = enc2 = enc3 = enc4 = "";
        } while (i < input.length);
        return output;
    }
    
    function decode64(input)
    {
        var output = "";
        var chr1, chr2, chr3 = "";
        var enc1, enc2, enc3, enc4 = "";
        var i = 0;

        var base64test = /[^A-Za-z0-9\+\/\=]/g;
        if (base64test.exec(input))
        {
            alert("There were invalid base64 characters in the input text.\n" +
            "Valid base64 characters are A-Z, a-z, 0-9, '+', '/', and '='\n" +
            "Expect errors in decoding.");
        }
        input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");

        do
        {
            enc1 = keyStr.indexOf(input.charAt(i++));
            enc2 = keyStr.indexOf(input.charAt(i++));
            enc3 = keyStr.indexOf(input.charAt(i++));
            enc4 = keyStr.indexOf(input.charAt(i++));

            chr1 = (enc1 << 2) | (enc2 >> 4);
            chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
            chr3 = ((enc3 & 3) << 6) | enc4;

            output = output + String.fromCharCode(chr1);

            if (enc3 != 64)
            {
                output = output + String.fromCharCode(chr2);
            }
            if (enc4 != 64)
            {
                output = output + String.fromCharCode(chr3);
            }

            chr1 = chr2 = chr3 = "";
            enc1 = enc2 = enc3 = enc4 = "";

        } while (i < input.length);
        return unescape(output);
    }