var ua = navigator.userAgent.toLowerCase();
if (ua.indexOf(" chrome/") >= 0 || ua.indexOf(" firefox/") >= 0 || ua.indexOf(' gecko/') >= 0) {
	var StringMaker = function () {
		this.str = "";
		this.length = 0;
		this.append = function (s) {
			this.str += s;
			this.length += s.length;
		}
		this.prepend = function (s) {
			this.str = s + this.str;
			this.length += s.length;
		}
		this.toString = function () {
			return this.str;
		}
	}
} else {
	var StringMaker = function () {
		this.parts = [];
		this.length = 0;
		this.append = function (s) {
			this.parts.push(s);
			this.length += s.length;
		}
		this.prepend = function (s) {
			this.parts.unshift(s);
			this.length += s.length;
		}
		this.toString = function () {
			return this.parts.join('');
		}
	}
}

var keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

function encode64(input) {
	var output = new StringMaker();
	var chr1, chr2, chr3;
	var enc1, enc2, enc3, enc4;
	var i = 0;

	while (i < input.length) {
		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.append(keyStr.charAt(enc1) + keyStr.charAt(enc2) + keyStr.charAt(enc3) + keyStr.charAt(enc4));
   }
   
   return output.toString();
}