var pwd = theform.PassWord.value;
var rndNum = 394058;
rndNum = rndNum.toString();
var curPos = 0;
var tmpStr,EnCryptStr = "";
for(Cnt=0;Cnt<pwd.length;Cnt++){
    if(Cnt % rndNum.length == 0 ) curPos = 0;
    tmpStr = pwd.substring(Cnt,Cnt+1);
    EnCryptStr += String.fromCharCode(tmpStr.charCodeAt(0) - Cnt - rndNum.substring(curPos,curPos+1));
    curPos +=1;
}
theform.PassWord.value = EnCryptStr;//Assigned the EncryptPassword value to the PassWord TextFiled
theform.EnRndNum.value = rndNum;

用php还原

$pwd = "";
$rndNum = "394058";
$curPos = 0;
$tmpStr = "";
$EnCryptStr = "";
for($Cnt=0;$Cnt<strlen($pwd);$Cnt++)
        {
            if($Cnt % strlen($rndNum) == 0 ) $curPos = 0;
            $tmpStr = substr($pwd,$Cnt,1);
            $EnCryptStr = $EnCryptStr. fromCharCode(charCodeAt($tmpStr) - $Cnt - substr($rndNum,$curPos,1));
                        $curPos +=1; 
        }
echo $EnCryptStr;
echo ''<br>'';
echo $rndNum;
echo ''<br>'';
echo EncryptString($EnCryptStr);

function fromCharCode($codes) {
   if (is_scalar($codes)) $codes= func_get_args();
   $str= '''';
   foreach ($codes as $code) $str.= chr($code);
   return $str;
}

function charCodeAt($word) {
  if (is_array($word))
    $arr = $word;
  else  
    $arr = str_split($word);
  $bin_str = '''';
  foreach ($arr as $value)
    $bin_str .= decbin(ord($value));
  $bin_str = preg_replace(''/^.{4}(.{4}).{2}(.{6}).{2}(.{6})$/'',''$1$2$3'', $bin_str);
  return bindec($bin_str);
}

原函数

Function EncryptString(InputText , ThePassword )''用户口令加密 
    Dim il_bit, il_x, il_y, il_z, il_len, i 
    Dim is_out 
    Password = InputText 
    il_len = Len(Password) 
    il_x = 0 
    il_y = 0 
    is_out = "" 

    For i = 1 To il_len 
        il_bit = AscW(Mid(Password, i, 1)) ''W系列支持unicode 
        il_y = (il_bit * 13 Mod 256) + il_x 
        is_out = is_out & ChrW(Fix(il_y)) ''取整 int和fix区别: fix修正负数 
        il_x = il_bit * 13 / 256 
    Next 

    is_out = is_out & ChrW(Fix(il_x)) 
    Password = is_out 
    il_len = Len(Password) 
    il_x = 0 
    il_y = 0 
    is_out = "" 

    For i = 1 To il_len 
        il_bit = AscW(Mid(Password, i, 1)) ''取前4位值 
        il_y = il_bit / 16 + 64 
        is_out = is_out & ChrW(Fix(il_y)) ''取后4位值 
        il_y = (il_bit Mod 16) + 64 
        is_out = is_out & ChrW(Fix(il_y)) 
    Next 

    EncryptString = is_out 
    End Function 
}

用php还原

function EncryptString($Password){      //密码前端加密部分
    $il_len = strlen($Password);
    $il_x = 0;
    $il_y = 0;
    $is_out = "";

    for($i=0;$i< $il_len;$i++){
        $il_bit = ord(substr($Password, $i, 1));
        $il_y = ($il_bit * 13 % 256) + $il_x;
        $is_out = $is_out. Chr(fix($il_y));
        $il_x = $il_bit * 13 / 256;
    }

    $is_out = $is_out. Chr(fix($il_x));
    $Password = $is_out;
    $il_len = strlen($Password);
    $il_x = 0;
    $il_y = 0;
    $is_out = "";

    for($i=0;$i<$il_len;$i++){
        $il_bit = ord(substr($Password, $i, 1));
        $il_y = $il_bit / 16 + 64; 
        $is_out = $is_out. Chr(fix($il_y));
        $il_y = ($il_bit % 16) + 64; 
        $is_out = $is_out. Chr(fix($il_y));

    }

    return $is_out; 
}

function fix($il_y) {
   if(floor($il_y) < 0){
        return floor($il_y)+1;
   }else{
        return floor($il_y);
   }
}