NC3 Jule CTF - Convert (quick hack)

convert.js

const fs = require('fs');

function hex2a(hexx) {
    var hex = hexx.toString();
    var str = '';
    for (var i = 0; i < hex.length; i += 2)
        str += String.fromCharCode(parseInt(hex.substr(i, 2), 16));
    return str;
}

console.time('Generate');

fs.readFile('secret', { encoding: 'utf8' }, function(err, data) {
    const hexArray = data.split( /(?=(?:...)*$)/ );

    let stringArray = hexArray.map(function(code) {
        let hexCode = code.replace('x','');
        return hex2a(hexCode);
    });

    var str = stringArray.join('');

    var last = 0;
    let painting = [];
    for(let nu = 0; nu < str.length / 299; nu++) {
        painting.push(str.substring(last, last + 299 ));
        last = last + 299
    }

    var out = painting.join('\n');

    fs.writeFile('message-breaks-2.txt', out, (err) => {
        if (err) throw err;
        console.log('The file has been saved!');
        console.timeEnd('Generate');
    });
});