text: /*
   * This file is part of FTB Launcher.
   *
   * Copyright © 2012-2018, FTB Launcher Contributors <https://github.com/Slowpoke101/FTBLaunch/>
   * FTB Launcher is 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 net.ftb.util;
  
  import net.ftb.log.Logger;
  import org.apache.commons.codec.binary.Base64;
  import org.apache.commons.codec.digest.DigestUtils;
  
  import java.io.UnsupportedEncodingException;
  import java.math.BigInteger;
  import java.util.Arrays;
  
  import javax.crypto.Cipher;
  import javax.crypto.spec.SecretKeySpec;
  
  public final class CryptoUtils {
  
      private CryptoUtils () {
      }
  
      /**
       * Newer implementation available if possible use {@link #decrypt(String str)}
       * @param str string to decrypt
       * @param key decryption key
       * @return decrypted string or "" if fails
       */
      @Deprecated
      public static String decryptLegacy (String str, byte[] key) {
          BigInteger in = new BigInteger(str, 16).xor(new BigInteger(1, key));
          try {
              return new String(in.toByteArray(), "utf8");
          } catch (UnsupportedEncodingException e) {
              return "";
          } catch (NumberFormatException e) {
              Logger.logError("Error occurred during legacy decryption");
              return "";
          }
      }
  
      /**
       * Newer implementation available if possible use {@link #encrypt(String str)}
       * @param str string to decrypt
       * @param key decryption key
       * @return decrypted string or "" if fails
       */
      @Deprecated
      public static String encryptLegacy (String str, byte[] key) {
          BigInteger str2;
          try {
              str2 = new BigInteger(str.getBytes("utf8")).xor(new BigInteger(1, key));
          } catch (UnsupportedEncodingException e) {
              return "";
          }
          return String.format("%040x", str2);
      }
  
      /**
       * Method to AES decrypt string if fails, will attempt to use {@link #decryptLegacy(String str, byte[] key)}
       * @param str string to decrypt
       * @return decrypted string or "" if legacy fails
       */
      public static String decrypt (String str) {
          byte[] keyMac = OSUtils.getMacAddress();
          byte[] keyHardware = OSUtils.getHardwareID();
          String s;
          try {
              Cipher aes = Cipher.getInstance("AES");
              if (keyHardware != null && keyHardware.length > 0) {
                  Logger.logDebug("trying with hardware id");
                  try {
                      aes.init(Cipher.DECRYPT_MODE, new SecretKeySpec(pad(keyHardware), "AES"));
                      s = new String(aes.doFinal(Base64.decodeBase64(str)), "utf8");
                      if (s.startsWith("FDT:") && s.length() > 4) {
                          Logger.logDebug("hardware id ok");
                          return s.split(":", 2)[1];// it was decrypted with HW UUID
                      }
                  } catch (Exception e) {
                      Logger.logDebug("foo", e);
                  }
              }
  
              // did not open, try again with old mac based key
              Logger.logDebug("Tryinng with mac address");
              aes.init(Cipher.DECRYPT_MODE, new SecretKeySpec(pad(keyMac), "AES"));
              s = new String(aes.doFinal(Base64.decodeBase64(str)), "utf8");
              if (s.startsWith("FDT:") && s.length() > 4) {
                  Logger.logDebug("mac address ok");
                  return s.split(":", 2)[1];//we don't want the decryption test
              } else {
                  Logger.logDebug("Trying some legacy");
                  return decryptLegacy(str, keyMac);
              }
          } catch (Exception e) {
              Logger.logError("Error Decrypting information, attempting legacy decryption", e);
              return decryptLegacy(str, keyMac);
          }
      }
  
      /**
       * Method to AES encrypt string if fails, will attempt to use {@link #encryptLegacy(String str, byte[] key)}
       * @param str string to encrypt
       * @return encrypted string or "" if legacy fails
       */
      public static String encrypt (String str) {
          byte[] keyMac = OSUtils.getMacAddress();
          byte[] keyHardware = OSUtils.getHardwareID();
          try {
              Cipher aes = Cipher.getInstance("AES");
              if (keyHardware != null && keyHardware.length > 0) {
                  Logger.logDebug("trying hardware id");
                  aes.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(pad(keyHardware), "AES"));
                  Logger.logDebug("hardware id ok");
                  return Base64.encodeBase64String(aes.doFinal(("FDT:" + str).getBytes("utf8")));
              }
              Logger.logDebug("trying mac address");
              aes.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(pad(keyMac), "AES"));
              Logger.logDebug("mac address ok");
              return Base64.encodeBase64String(aes.doFinal(("FDT:" + str).getBytes("utf8")));
          } catch (Exception e) {
              Logger.logError("Error Encrypting information, reverting to legacy format", e);
              return encryptLegacy(str, keyMac);
          }
      }
  
      /**
       * method to pad AES keys by using the sha1Hex hash on them
       * @param key key to pad
       * @return padded key
       */
      public static byte[] pad (byte[] key) {
          try {
              return Arrays.copyOf(DigestUtils.sha1Hex(key).getBytes("utf8"), 16);
          } catch (UnsupportedEncodingException e) {
              Logger.logError("error encoding padded key!", e);
              return Arrays.copyOf(DigestUtils.sha1Hex(key).getBytes(), 16);
          }
      }
  }
  