content: package emu.grasscutter.utils;
  
  import java.io.File;
  import java.nio.file.Path;
  import java.security.KeyFactory;
  import java.security.PrivateKey;
  import java.security.PublicKey;
  import java.security.SecureRandom;
  import java.security.spec.PKCS8EncodedKeySpec;
  import java.security.spec.X509EncodedKeySpec;
  import java.util.Map;
  import java.util.HashMap;
  import java.util.regex.Pattern;
  
  import emu.grasscutter.Grasscutter;
  
  public final class Crypto {
      private static final SecureRandom secureRandom = new SecureRandom();
  
      public static byte[] DISPATCH_KEY;
      public static byte[] DISPATCH_SEED;
  
      public static byte[] ENCRYPT_KEY;
      public static long ENCRYPT_SEED = Long.parseUnsignedLong("11468049314633205968");
      public static byte[] ENCRYPT_SEED_BUFFER = new byte[0];
  
      public static PrivateKey CUR_SIGNING_KEY;
  
      public static Map<Integer, PublicKey> EncryptionKeys = new HashMap<>();
  
      public static void loadKeys() {
          DISPATCH_KEY = FileUtils.readResource("/keys/dispatchKey.bin");
          DISPATCH_SEED = FileUtils.readResource("/keys/dispatchSeed.bin");
  
          ENCRYPT_KEY = FileUtils.readResource("/keys/secretKey.bin");
          ENCRYPT_SEED_BUFFER = FileUtils.readResource("/keys/secretKeyBuffer.bin");
  
          try {
              CUR_SIGNING_KEY = KeyFactory.getInstance("RSA")
                  .generatePrivate(new PKCS8EncodedKeySpec(FileUtils.readResource("/keys/SigningKey.der")));
  
              Pattern pattern = Pattern.compile("([0-9]*)_Pub\\.der");
              for (Path path : FileUtils.getPathsFromResource("/keys/game_keys")) {
                  if (path.toString().endsWith("_Pub.der")) {
  
                      var m = pattern.matcher(path.getFileName().toString());
  
                      if (m.matches())
                      {
                          var key = KeyFactory.getInstance("RSA")
                              .generatePublic(new X509EncodedKeySpec(FileUtils.read(path)));
  
                          EncryptionKeys.put(Integer.valueOf(m.group(1)), key);
                      }
                  }
              }
          }
          catch (Exception e) {
              Grasscutter.getLogger().error("An error occurred while loading keys.", e);
          }
      }
  
      public static void xor(byte[] packet, byte[] key) {
          try {
              for (int i = 0; i < packet.length; i++) {
                  packet[i] ^= key[i % key.length];
              }
          } catch (Exception e) {
              Grasscutter.getLogger().error("Crypto error.", e);
          }
      }
  
      public static byte[] createSessionKey(int length) {
          byte[] bytes = new byte[length];
          secureRandom.nextBytes(bytes);
          return bytes;
      }
  }
  