Javascript şifreleme mantığı konusunda yardım

var END_OF_INPUT=-1;var arrChrs=new Array("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","0","1","2","3","4","5","6","7","8","9","+","/");var reversegetFChars=new Array;for(var i=0;i<arrChrs.length;i++){reversegetFChars[arrChrs[i]]=i}var getFStr;var getFCount;function ntos(e){e=e.toString(16);if(e.length==1)e="0"+e;e="%"+e;return unescape(e)}function readReversegetF(){if(!getFStr)return END_OF_INPUT;while(true){if(getFCount>=getFStr.length)return END_OF_INPUT;var e=getFStr.charAt(getFCount);getFCount++;if(reversegetFChars[e]){return reversegetFChars[e]}if(e=="A")return 0}return END_OF_INPUT}function readgetF(){if(!getFStr)return END_OF_INPUT;if(getFCount>=getFStr.length)return END_OF_INPUT;var e=getFStr.charCodeAt(getFCount)&255;getFCount++;return e}function setgetFStr(e){getFStr=e;getFCount=0}function getF(e){setgetFStr(e);var t="";var n=new Array(4);var r=false;while(!r&&(n[0]=readReversegetF())!=END_OF_INPUT&&(n[1]=readReversegetF())!=END_OF_INPUT){n[2]=readReversegetF();n[3]=readReversegetF();t+=ntos(n[0]<<2&255|n[1]>>4);if(n[2]!=END_OF_INPUT){t+=ntos(n[1]<<4&255|n[2]>>2);if(n[3]!=END_OF_INPUT){t+=ntos(n[2]<<6&255|n[3])}else{r=true}}else{r=true}}return t}function doit(e){return unescape(getF(getF(e)))}

<script type="text/javascript">document.write(doit('UEdsbWNtRnRaU0J6Y21NOUltaDBkSEE2THk5MGFHVjJhV1JsYjNNdWRIWXZaVzFpWldRdE5ITnhPV1Z2ZEhwbllYSXpMVGN5T0hnME1UQXVhSFJ0YkNJZ2QyVmlhMmwwUVd4c2IzZEdkV3hzVTJOeVpXVnVQU0owY25WbElpQnRiM3BoYkd4dmQyWjFiR3h6WTNKbFpXNDlJblJ5ZFdVaUlHRnNiRzkzWm5Wc2JITmpjbVZsYmowaWRISjFaU0lnWm5KaGJXVmliM0prWlhJOUlqQWlJRzFoY21kcGJuZHBaSFJvUFNJd0lpQnRZWEpuYVc1b1pXbG5hSFE5SWpBaUlITmpjbTlzYkdsdVp6MGlibThpSUhkcFpIUm9QU0kzTWpnaUlHaGxhV2RvZEQwaU5ERXdJajQ4TDJsbWNtRnRaVDQ9'));</script>

<?php
echo base64_decode(base64_decode("UEdsbWNtRnRaU0J6Y21NOUltaDBkSEE2THk5MGFHVjJhV1JsYjNNdWRIWXZaVzFpWldRdE5ITnhPV1Z2ZEhwbllYSXpMVGN5T0hnME1UQXVhSFJ0YkNJZ2QyVmlhMmwwUVd4c2IzZEdkV3hzVTJOeVpXVnVQU0owY25WbElpQnRiM3BoYkd4dmQyWjFiR3h6WTNKbFpXNDlJblJ5ZFdVaUlHRnNiRzkzWm5Wc2JITmpjbVZsYmowaWRISjFaU0lnWm5KaGJXVmliM0prWlhJOUlqQWlJRzFoY21kcGJuZHBaSFJvUFNJd0lpQnRZWEpuYVc1b1pXbG5hSFE5SWpBaUlITmpjbTlzYkdsdVp6MGlibThpSUhkcFpIUm9QU0kzTWpnaUlHaGxhV2RvZEQwaU5ERXdJajQ4TDJsbWNtRnRaVDQ9"));
?>