在中国人民银行官网发现这样一行代码

http://www.pbc.gov.cn
这是官网链接，关闭javascript打开后，显示：
请开启JavaScript并刷新该页.
html源码如下：

<html>
<head>
</head>
<body>
<noscript>
<h1><strong>请开启JavaScript并刷新该页.</strong></h1>
</noscript>
<script type="text/javascript">
eval(function(p,a,c,k,e,d){e=function(c){return(c<a?'':e(parseInt(c/a)))+((c=c%a)>32?String.fromCharCode(c+32):c.toString(33))};if(!''.replace(/^/,String)){while(c--)d[e(c)]=k[c]||e(c);k=[function(e){return d[e]}];e=function(){return'\\w+'};c=1};while(c--)if(k[c])p=p.replace(new RegExp('\\b'+e(c)+'\\b','g'),k[c]);return p}('15 D="k";15 1a="i";15 1b="l";15 11=7;15 F = "e+/=";J g(10) {15 U, N, R;15 o, p, q;R = 10.S;N = 0;U = "";17 (N < R) {o = 10.s(N++) & 6;O (N == R) {U += F.r(o >> a);U += F.r((o & 1) << c);U += "==";n;}p = 10.s(N++);O (N == R) {U += F.r(o >> a);U += F.r(((o & 1) << c) | ((p & 5) >> c));U += F.r((p & 4) << a);U += "=";n;}q = 10.s(N++);U += F.r(o >> a);U += F.r(((o & 1) << c) | ((p & 5) >> c));U += F.r(((p & 4) << a) | ((q & 3) >> d));U += F.r(q & 2);}W U;}J H(){15 16= 19.Q||B.C.u||B.m.u;15 K= 19.P||B.C.t||B.m.t;O (16*K <= 9) {W 14;}15 1d = 19.Y;15 1e = 19.Z;O (1d + 16 <= 0 || 1e + K <= 0 || 1d >= 19.X.18 || 1e >= 19.X.M) {W 14;}W G;}J h(){15 12 = 1a+1b;15 L = 0;15 N    = 0;I(N = 0; N < 12.S; N++) {L += 12.s(N);}L *= b;L += 8;W "j"+L;}J f(){O(H()) {} E {15 A = ""; A = "1c="+g(11.13()) + "; V=/";B.w = A; 15 v = h();A = "1a="+g(v.13()) + "; V=/";B.w = A;   19.T=D;}}f();',59,74,'0|0x3|0x3f|0xc0|0xf|0xf0|0xff|10|111111|120000|2|31|4|6|ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789|HXXTTKKLLPPP5|KTKY2RBD9NHPBCIHV9ZMEQQDARSLVFDU|QWERTASDFGXYSF|RANDOMSTR14559|WZWS_CONFIRM_PREFIX_LABEL10|/|STRRANDOM14559|body|break|c1|c2|c3|charAt|charCodeAt|clientHeight|clientWidth|confirm|cookie|cookieString|document|documentElement|dynamicurl|else|encoderchars|false|findDimensions|for|function|h|hash|height|i|if|innerHeight|innerWidth|len|length|location|out|path|return|screen|screenX|screenY|str|template|tmp|toString|true|var|w|while|width|window|wzwschallenge|wzwschallengex|wzwstemplate|x|y'.split('|'),0,{}))
</script>

</body>
</html>

浏览器不支持javascript就直接显示<noscript>里的内容，支持在运行下边的js脚本。
我不明白的是，下面的脚本看不出它是怎么运行的，可以把DOM树修改成最终需要的主页，求指教

alect

2015-07-24 17:31:37 +08:00

加密了
var dynamicurl="/";
var wzwschallenge="RANDOMSTR14559";
var wzwschallengex="STRRANDOM14559";
var template=10;
var encoderchars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
function KTKY2RBD9NHPBCIHV9ZMEQQDARSLVFDU(str)
{
var out, i, len;
var c1, c2, c3;
len = str.length;
i = 0;
out = "";
while (i < len)
{
c1 = str.charCodeAt(i++) & 0xff;
if (i == len)
{
out += encoderchars.charAt(c1 >> 2);
out += encoderchars.charAt((c1 & 0x3) << 4);
out += "==";
break;
}
c2 = str.charCodeAt(i++);
if (i == len)
{
out += encoderchars.charAt(c1 >> 2);
out += encoderchars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xf0) >> 4));
out += encoderchars.charAt((c2 & 0xf) << 2);
out += "=";
break;
}
c3 = str.charCodeAt(i++);
out += encoderchars.charAt(c1 >> 2);
out += encoderchars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xf0) >> 4));
out += encoderchars.charAt(((c2 & 0xf) << 2) | ((c3 & 0xc0) >> 6));
out += encoderchars.charAt(c3 & 0x3f);
}
return out;
}
function findDimensions()
{
var w= window.innerWidth||document.documentElement.clientWidth||document.body.clientWidth;
var h= window.innerHeight||document.documentElement.clientHeight||document.body.clientHeight;
if (w*h <= 120000)
{
return true;
}
var x = window.screenX;
var y = window.screenY;
if (x + w <= 0 || y + h <= 0 || x >= window.screen.width || y >= window.screen.height)
{
return true;
}
return false;
}
function QWERTASDFGXYSF()
{
var tmp = wzwschallenge+wzwschallengex;
var hash = 0;
var i = 0;
for(i = 0;
i < tmp.length;
i++)
{
hash += tmp.charCodeAt(i);
}
hash *= 31;
hash += 111111;
return "WZWS_CONFIRM_PREFIX_LABEL10"+hash;
}
function HXXTTKKLLPPP5()
{
if(findDimensions())
{
}
else
{
var cookieString = "";
cookieString = "wzwstemplate="+KTKY2RBD9NHPBCIHV9ZMEQQDARSLVFDU(template.toString()) + ";
path=/";
document.cookie = cookieString;
var confirm = QWERTASDFGXYSF();
cookieString = "wzwschallenge="+KTKY2RBD9NHPBCIHV9ZMEQQDARSLVFDU(confirm.toString()) + ";
path=/";
document.cookie = cookieString;
window.location=dynamicurl;
}
}
HXXTTKKLLPPP5();