Added support for CrazyLogin and LoginSecurity + Code cleanup + Added a lot of comments + Version independent

src/main/java/com/github/games647/fastlogin/Encryption.java

@@ -0,0 +1,135 @@
+package com.github.games647.fastlogin;
+
+import java.io.UnsupportedEncodingException;
+import java.security.GeneralSecurityException;
+import java.security.InvalidKeyException;
+import java.security.Key;
+import java.security.KeyFactory;
+import java.security.KeyPair;
+import java.security.KeyPairGenerator;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.security.PrivateKey;
+import java.security.PublicKey;
+import java.security.spec.InvalidKeySpecException;
+import java.security.spec.X509EncodedKeySpec;
+
+import javax.crypto.BadPaddingException;
+import javax.crypto.Cipher;
+import javax.crypto.IllegalBlockSizeException;
+import javax.crypto.NoSuchPaddingException;
+import javax.crypto.SecretKey;
+import javax.crypto.spec.IvParameterSpec;
+import javax.crypto.spec.SecretKeySpec;
+
+/**
+ * Source:
+ * https://github.com/bergerkiller/CraftSource/blob/master/net.minecraft.server/MinecraftEncryption.java
+ *
+ * Remapped by:
+ * https://github.com/Techcable/MinecraftMappings/tree/master/1.8
+ */
+public class Encryption {
+
+    public static KeyPair generateKeyPair() {
+        try {
+            KeyPairGenerator keypairgenerator = KeyPairGenerator.getInstance("RSA");
+
+            keypairgenerator.initialize(1024);
+            return keypairgenerator.generateKeyPair();
+        } catch (NoSuchAlgorithmException nosuchalgorithmexception) {
+            //Should be existing in every vm
+            return null;
+        }
+    }
+
+    public static byte[] getServerIdHash(String serverId, PublicKey publickey, SecretKey secretkey) {
+        try {
+            return digestOperation("SHA-1"
+                    , new byte[][]{serverId.getBytes("ISO_8859_1"), secretkey.getEncoded(), publickey.getEncoded()});
+        } catch (UnsupportedEncodingException unsupportedencodingexception) {
+            unsupportedencodingexception.printStackTrace();
+            return null;
+        }
+    }
+
+    private static byte[] digestOperation(String algo, byte[]... content) {
+        try {
+            MessageDigest messagedigest = MessageDigest.getInstance(algo);
+            int dataLength = content.length;
+
+            for (int i = 0; i < dataLength; ++i) {
+                byte[] abyte1 = content[i];
+
+                messagedigest.update(abyte1);
+            }
+
+            return messagedigest.digest();
+        } catch (NoSuchAlgorithmException nosuchalgorithmexception) {
+            nosuchalgorithmexception.printStackTrace();
+            return null;
+        }
+    }
+
+    public static PublicKey decodePublicKey(byte[] encodedKey) {
+        try {
+            X509EncodedKeySpec x509encodedkeyspec = new X509EncodedKeySpec(encodedKey);
+            KeyFactory keyfactory = KeyFactory.getInstance("RSA");
+
+            return keyfactory.generatePublic(x509encodedkeyspec);
+        } catch (NoSuchAlgorithmException | InvalidKeySpecException nosuchalgorithmexception) {
+            ;
+        }
+
+        System.err.println("Public key reconstitute failed!");
+        return null;
+    }
+
+    public static SecretKey decryptSharedKey(PrivateKey privatekey, byte[] encryptedSharedKey) {
+        return new SecretKeySpec(decryptData(privatekey, encryptedSharedKey), "AES");
+    }
+
+    public static byte[] decryptData(Key key, byte[] abyte) {
+        return cipherOperation(Cipher.DECRYPT_MODE, key, abyte);
+    }
+
+    private static byte[] cipherOperation(int operationMode, Key key, byte[] data) {
+        try {
+            return createCipherInstance(operationMode, key.getAlgorithm(), key).doFinal(data);
+        } catch (IllegalBlockSizeException | BadPaddingException illegalblocksizeexception) {
+            illegalblocksizeexception.printStackTrace();
+        }
+
+        System.err.println("Cipher data failed!");
+        return null;
+    }
+
+    private static Cipher createCipherInstance(int operationMode, String cipherName, Key key) {
+        try {
+            Cipher cipher = Cipher.getInstance(cipherName);
+
+            cipher.init(operationMode, key);
+            return cipher;
+        } catch (InvalidKeyException | NoSuchAlgorithmException | NoSuchPaddingException invalidkeyexception) {
+            invalidkeyexception.printStackTrace();
+        }
+
+        System.err.println("Cipher creation failed!");
+        return null;
+    }
+
+    public static Cipher createBufferedBlockCipher(int operationMode, Key key) {
+        try {
+            Cipher cipher = Cipher.getInstance("AES/CFB8/NoPadding");
+
+            cipher.init(operationMode, key, new IvParameterSpec(key.getEncoded()));
+            return cipher;
+        } catch (GeneralSecurityException generalsecurityexception) {
+            throw new RuntimeException(generalsecurityexception);
+        }
+    }
+
+    private Encryption() {
+        //utility
+    }
+}