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;

        // remove all characters that are not A-Z, a-z, 0-9, +, /, or =
        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);
}