RJ Level 7 Password Recover

rj.html

<input type="text" id="pwd"></input>
<input type="text" id="plain"></input>
<button onclick="crackPassword(document.getElementById('pwd').value);"></button>
<script type="text/javascript" src="rj.js"></script>

rj.js

/* From http://www.ifm.net.nz/cookbooks/passwordcracker.html */
function crackPassword(str)
{
    var crypttext=str.toUpperCase()
    var plaintext=''
    var xlat="*@##Wxf^cOurGer*mArKKDHSUBsgvca69834ncxv9873254k;fg87"
    var seed, i, val=0

    if(crypttext.length & 1) {
        console.log("Error out 1: Crypt text has odd length")
        return
    }

    seed = (crypttext.charCodeAt(0) - 0x30) * 10 + crypttext.charCodeAt(1) - 0x30

    if (seed > 15 || !isDigit(crypttext.charAt(0)) || !isDigit(crypttext.charAt(1))) {
        console.log("Error out 2")
        return
    }

    for (i = 2 ; i <= crypttext.length; i++) {
        if(i !=2 && !(i & 1)) { // i != 2 && i is EVEN
            console.log('When i = ' + i + ', val = ' + val + ', current char is ' + String.fromCharCode(val ^ xlat.charCodeAt(seed)) + ' (' + (val ^ xlat.charCodeAt(seed)) + '), seed = ' + seed + ' (xlat charCode is ' + xlat.charCodeAt(seed) + ')')
            plaintext+=String.fromCharCode(val ^ xlat.charCodeAt(seed++))
            seed%=xlat.length
            val = 0;
        }

        val *= 16

        /* Convert to hex start */
        if(isDigit(crypttext.charAt(i))) {
            val += crypttext.charCodeAt(i) - 0x30
            continue
        }

        if(crypttext.charCodeAt(i) >= 0x41 && crypttext.charCodeAt(i) <= 0x46) {
            val += crypttext.charCodeAt(i) - 0x41 + 0x0a
            continue
        }
        /* Convert to hex end. Now val is hex value of current char */
        
        if(crypttext.length != i) {
            console.log("Error out 3")
            return
        }
    }

    document.getElementById('plain').value=plaintext
}

function isDigit(theDigit) 
{ 
    var digitArray = new Array('0','1','2','3','4','5','6','7','8','9')

    for (j = 0; j < digitArray.length; j++)  {
        if (theDigit == digitArray[j]) 
            return true 
    } 
    return false 
}