/*
 * Copyright (C) 2013 The WLANAudit project contributors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package es.glasspixel.wlanaudit.keyframework;

import java.util.ArrayList;
import java.util.List;
import java.util.Locale;


/**
 * Default key calculator for networks with SSID form WLANXXXXXX, YACOMXXXXXX
 * and WiFiXXXXXX Generates a dictionary of ten possible keys.
 * <p/>
 * Original algorithm from Mambostar
 * <p/>
 * More info available at:
 * <p/>
 * http://foro.seguridadwireless.net/comunicados-y-noticias
 * /wlan4xx-algoritmo-routers-yacom/
 *
 * @author Roberto Estrada
 */
public class WiFiXXXXXXKeyCalculator implements IKeyCalculator {
    /**
     * {@inheritDoc}
     */
    @Override
    public List<String> getKey(NetData network) {
        // Derived keys
        List<String> keyList = new ArrayList<String>();

        // Public data
        String essid = trimSSID(network.SSID);
        String bssid = network.BSSID.replaceAll(":", "").toUpperCase(Locale.getDefault());

        // Data preparation
        char[] essid_c = essid.toCharArray();
        char[] bssid_c = bssid.toCharArray();

        for (int i = 0; i < essid_c.length; i++) {
            if (essid_c[i] >= 65) {
                essid_c[i] -= 55;
            }
        }

        for (int i = 0; i < bssid_c.length; i++) {
            if (bssid_c[i] >= 65) {
                bssid_c[i] -= 55;
            }
        }

        // Serial data (derived from public data)
        char S8, S9, S10, M9, M10, M11, M12;
        S8 = (char) (essid_c[3] & 15);
        S9 = (char) (essid_c[4] & 15);
        S10 = (char) (essid_c[5] & 15);

        // M values (MAC) obtained from BSSID and ESSID
        M9 = essid_c[1];
        M10 = (char) (essid_c[2] & 15);
        M11 = bssid_c[10];
        M12 = bssid_c[11];

        // Key derivation
        for (int S7 = 0; S7 < 10; S7++) {
            // Key values
            int X1, X2, X3, Y1, Y2, Y3, Z1, Z2, Z3, W1, W2, W3, W4;

            // S7+S8+M11+M12
            int K1 = S7 + S8 + M11 + M12;
            // M9+M10+S9+S10
            int K2 = M9 + M10 + S9 + S10;

            // X values
            X1 = K1 ^ S10;
            X2 = K1 ^ S9;
            X3 = K1 ^ S8;
            // Y values
            Y1 = K2 ^ M10;
            Y2 = K2 ^ M11;
            Y3 = K2 ^ M12;
            // Z values
            Z1 = M11 ^ S10;
            Z2 = M12 ^ S9;
            Z3 = K1 ^ K2;
            // W values
            W1 = X1 ^ Z2;
            W2 = Y2 ^ Y3;
            W3 = Y1 ^ X3;
            W4 = Z3 ^ X2;

            // Result composition
            String result = dec2hex(W4) + dec2hex(X1) + dec2hex(Y1)
                    + dec2hex(Z1) + dec2hex(W1) + dec2hex(X2) + dec2hex(Y2)
                    + dec2hex(Z2) + dec2hex(W2) + dec2hex(X3) + dec2hex(Y3)
                    + dec2hex(Z3) + dec2hex(W3);

            keyList.add(result.toUpperCase(Locale.getDefault()));
        }

        return keyList;
    }

    private String trimSSID(String ssid) {
        String result = null;
        if (ssid.contains("WLAN")) {
            result = ssid.replace("WLAN", "").toUpperCase(Locale.getDefault());
        } else if (ssid.contains("YaCOM")) {
            result = ssid.replace("YaCOM", "").toUpperCase(Locale.getDefault());
        } else if (ssid.contains("YaCom")) {
            result = ssid.replace("YaCom", "").toUpperCase(Locale.getDefault());
        } else if (ssid.contains("WiFi")) {
            result = ssid.replace("WiFi", "").toUpperCase(Locale.getDefault());
        } else if (ssid.contains("WIFI")) {
            result = ssid.replace("WIFI", "").toUpperCase(Locale.getDefault());
        }
        return result;
    }

    private String dec2hex(int dec) {
        return Integer.toHexString(dec & 0xf);
    }

}