JavaScript base64随机字符混淆加密、解密

<script>
	var d='YmxvZy5pc3d0Zi5jb20g5LyK5oCd572R5ouT';
	console.log(decodeURIComponent(escape(window.atob(d))));
	
	var str='lizhenqiu.com 伊思网拓';
	console.log(window.btoa(unescape(encodeURIComponent(str))));
	
;(function(base64){
	var substring='substring',
		split='split',
		reverse='reverse',
		join='join',
		toString='toString',
		substr='substr',
		replace='replace',
		fn={
		getHex: function(str) {//获取前4位标记数字
			return {
				str: str[substring](4),//排除前4位字符串
				hex: str[substring](0, 4)[split]("")[reverse]()[join]("")//前4位倒序
			}
		},
		getDec: function(str) {//获取混淆字符位置坐标
			str = parseInt(str, 16)[toString]();//前4位倒序的16进制
			str[substring](0, 2)[split]("");
			return {
				pre: str[substring](0, 2)[split](""),//前面坐标
				tail: str[substring](2)[split]("")//后面坐标
			}
		},
		delStr: function(str, pos) {//混淆的字符抽取
			var s = str[substring](0, pos[0]),
				del = str[substr](pos[0], pos[1]);//需替换的字符
			return s + str[substring](pos[0])[replace](del, "");//返回替换完成后的base64字符串
		},
		getPos: function(str, pos) {
			return [str.length - pos[0] - pos[1],pos[1]];
		},
		decode: function(str) {//解密
			var sh = this.getHex(str),//获取前4位标记数字
				pos = this.getDec(sh.hex),//获取混淆位置坐标
				d = this.delStr(sh.str, pos.pre);//前面混淆的字符抽取
				d=this.delStr(d, this.getPos(d, pos.tail));
			return decodeURIComponent(escape(window.atob(d)));//base64转成utf-8(兼容中文)
		},
		encode:function(str){//加密
			var base64=window.btoa(unescape(encodeURIComponent(str))),//转换成base64格式
				random=this.getRanNum(base64),//获取16进制是4位数的随机字符
				pos = this.getDec(random);//获取混淆位置坐标
			base64 = this.addStr(base64, pos);//插入混淆字符
			//console.log(random,pos)
			return random[toString]()[split]("")[reverse]()[join]("")+base64;
		},
		addStr: function(str, pos) {//混淆的字符插入
			var r1=this.getRanStr(pos.pre[1]),//获取随机字符串(前)
				r2=this.getRanStr(pos.tail[1]),//获取随机字符串(后)
				pre=this.insertStr(str,r1,pos.pre[0]),//插入随机字符串(前)
				tail=pre.length - pos.tail[0];
			str=this.insertStr(pre,r2,tail);//插入随机字符串(后)
			return str;
		},
		insertStr:function(str,addstr,pos){//往指定位置插入字符串
			return str[substring](0,pos)+addstr+str[substring](pos);
		},
		getRanNum:function(str){//获取16进制是4位数的4位随机字符
			var ranArr=[];
			;(function(){
				var n='',
					length=str.length;
				/** 4101开始16进制是4位数 **/
				for(var i=4101;i<=9999;i++){//找出所有符合要求的16进制4位数
					n=i[toString](16);//16转成10
					if(length>=8&&!(Math.floor(i/100)%10===0||i%10===0)&&n.length===4){
					//正常的base64编码长度大于8才前后加混淆字符
						//console.log(i,n);
						if(Math.floor(i/1000)<=length/2&&Math.floor(i%100/10)<=length/2){//混淆位置不能大于长度一半
							ranArr.push(n);
						}
					}else if(i%100===0&&n.length===4){//只在前面插入混淆字符
						if(Math.floor(i/1000)<=length){//混淆位置不能大于长度
							ranArr.push(n);
						}
					}
				}
			}());
			var length=ranArr.length,
				ran = Math.round(Math.random()*(length-1));
			return ranArr[ran];
		},
		getRanStr:function(num){//获取指定个数随机字符串
			var str=[0,1,2,3,4,5,6,7,8,9,'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z','+'],
				length=str.length,
				res = "";
			 for(; num-- ;) {
				 var id = Math.round(Math.random()*(length-1));
				 res += str[id];
			 }
			 return res;
		}
	}
	base64.tranCode=fn;
	window.base64=base64;
}(window.base64||{}));

	var d='1502YmxvZy5pLgc3d0Zi5jb20g5LyK5oCd5tRP72R5ouT';
	console.log(base64.tranCode.decode(d));
	
	var str='lizhenqiu.com 伊思网拓';
	var de=base64.tranCode.encode(str);
	console.log(de);
	console.log(base64.tranCode.decode(de));
	
</script>