<!--
function str_unrot(debut, chaine, fin){
var known_letters = 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 count_known_letters = known_letters.length;
var key = (chaine.length)%count_known_letters;   
var out = "";
for ( var i=0; i<chaine.length; i++ ) {
    current = chaine.charAt(i);
    if ( isInArray(known_letters, current) ) {
          for ( var j=0; j<count_known_letters; j++ ) {
            if ( known_letters[j] == current ) {
               break;
            }
          }
		   currentIndiceLetter = j;
          newIndiceLetter = (currentIndiceLetter-key)%count_known_letters;
          if ( newIndiceLetter < 0 ) {
            newIndiceLetter += count_known_letters;
         }
         out += known_letters[newIndiceLetter];
      } else {
         out += current;
      }
   }
   document.write(debut+out+fin);    
}

//---------------------------------------------------
function isInArray (_array,_value) {
  var _valueFound = false;
  if (typeof _array != 'undefined' && _array != null && typeof _array.length == 'number') {
    for (var _elementNo = 0; _elementNo < _array.length && !_valueFound; _elementNo++)
      _valueFound = _array [_elementNo] === _value
    ;
  }
  return _valueFound;
}      
//-->