Added AES utility class from baeldung and updated copyright notice for ZipUtils which was based on code from the same author. This code still needs reviewing and modifying but it's a good starting point for AES encryption and decryption.

src/main/java/org/qortal/crypto/AES.java

@@ -0,0 +1,181 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2017 Eugen Paraschiv
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package org.qortal.crypto;
+
+import javax.crypto.Cipher;
+import javax.crypto.IllegalBlockSizeException;
+import javax.crypto.NoSuchPaddingException;
+import javax.crypto.SecretKey;
+import javax.crypto.BadPaddingException;
+import javax.crypto.KeyGenerator;
+import javax.crypto.SecretKeyFactory;
+import javax.crypto.SealedObject;
+import javax.crypto.spec.IvParameterSpec;
+import javax.crypto.spec.PBEKeySpec;
+import javax.crypto.spec.SecretKeySpec;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.Serializable;
+import java.security.InvalidAlgorithmParameterException;
+import java.security.InvalidKeyException;
+import java.security.NoSuchAlgorithmException;
+import java.security.SecureRandom;
+import java.security.spec.InvalidKeySpecException;
+import java.security.spec.KeySpec;
+import java.util.Base64;
+
+public class AES {
+
+    public static String encrypt(String algorithm, String input, SecretKey key, IvParameterSpec iv)
+            throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidAlgorithmParameterException,
+            InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
+        Cipher cipher = Cipher.getInstance(algorithm);
+        cipher.init(Cipher.ENCRYPT_MODE, key, iv);
+        byte[] cipherText = cipher.doFinal(input.getBytes());
+        return Base64.getEncoder()
+                .encodeToString(cipherText);
+    }
+
+    public static String decrypt(String algorithm, String cipherText, SecretKey key, IvParameterSpec iv)
+            throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidAlgorithmParameterException,
+            InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
+        Cipher cipher = Cipher.getInstance(algorithm);
+        cipher.init(Cipher.DECRYPT_MODE, key, iv);
+        byte[] plainText = cipher.doFinal(Base64.getDecoder()
+                .decode(cipherText));
+        return new String(plainText);
+    }
+
+    public static SecretKey generateKey(int n) throws NoSuchAlgorithmException {
+        KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
+        keyGenerator.init(n);
+        SecretKey key = keyGenerator.generateKey();
+        return key;
+    }
+
+    public static SecretKey getKeyFromPassword(String password, String salt)
+            throws NoSuchAlgorithmException, InvalidKeySpecException {
+        SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
+        KeySpec spec = new PBEKeySpec(password.toCharArray(), salt.getBytes(), 65536, 256);
+        SecretKey secret = new SecretKeySpec(factory.generateSecret(spec)
+                .getEncoded(), "AES");
+        return secret;
+    }
+
+    public static IvParameterSpec generateIv() {
+        byte[] iv = new byte[16];
+        new SecureRandom().nextBytes(iv);
+        return new IvParameterSpec(iv);
+    }
+
+    public static void encryptFile(String algorithm, SecretKey key, IvParameterSpec iv,
+                                   File inputFile, File outputFile) throws IOException, NoSuchPaddingException,
+            NoSuchAlgorithmException, InvalidAlgorithmParameterException, InvalidKeyException,
+            BadPaddingException, IllegalBlockSizeException {
+        Cipher cipher = Cipher.getInstance(algorithm);
+        cipher.init(Cipher.ENCRYPT_MODE, key, iv);
+        FileInputStream inputStream = new FileInputStream(inputFile);
+        FileOutputStream outputStream = new FileOutputStream(outputFile);
+        byte[] buffer = new byte[64];
+        int bytesRead;
+        while ((bytesRead = inputStream.read(buffer)) != -1) {
+            byte[] output = cipher.update(buffer, 0, bytesRead);
+            if (output != null) {
+                outputStream.write(output);
+            }
+        }
+        byte[] outputBytes = cipher.doFinal();
+        if (outputBytes != null) {
+            outputStream.write(outputBytes);
+        }
+        inputStream.close();
+        outputStream.close();
+    }
+
+    public static void decryptFile(String algorithm, SecretKey key, IvParameterSpec iv,
+                                   File encryptedFile, File decryptedFile) throws IOException, NoSuchPaddingException,
+            NoSuchAlgorithmException, InvalidAlgorithmParameterException, InvalidKeyException,
+            BadPaddingException, IllegalBlockSizeException {
+        Cipher cipher = Cipher.getInstance(algorithm);
+        cipher.init(Cipher.DECRYPT_MODE, key, iv);
+        FileInputStream inputStream = new FileInputStream(encryptedFile);
+        FileOutputStream outputStream = new FileOutputStream(decryptedFile);
+        byte[] buffer = new byte[64];
+        int bytesRead;
+        while ((bytesRead = inputStream.read(buffer)) != -1) {
+            byte[] output = cipher.update(buffer, 0, bytesRead);
+            if (output != null) {
+                outputStream.write(output);
+            }
+        }
+        byte[] output = cipher.doFinal();
+        if (output != null) {
+            outputStream.write(output);
+        }
+        inputStream.close();
+        outputStream.close();
+    }
+
+    public static SealedObject encryptObject(String algorithm, Serializable object, SecretKey key,
+                                             IvParameterSpec iv) throws NoSuchPaddingException, NoSuchAlgorithmException,
+            InvalidAlgorithmParameterException, InvalidKeyException, IOException, IllegalBlockSizeException {
+        Cipher cipher = Cipher.getInstance(algorithm);
+        cipher.init(Cipher.ENCRYPT_MODE, key, iv);
+        SealedObject sealedObject = new SealedObject(object, cipher);
+        return sealedObject;
+    }
+
+    public static Serializable decryptObject(String algorithm, SealedObject sealedObject, SecretKey key,
+                                             IvParameterSpec iv) throws NoSuchPaddingException, NoSuchAlgorithmException,
+            InvalidAlgorithmParameterException, InvalidKeyException, ClassNotFoundException,
+            BadPaddingException, IllegalBlockSizeException, IOException {
+        Cipher cipher = Cipher.getInstance(algorithm);
+        cipher.init(Cipher.DECRYPT_MODE, key, iv);
+        Serializable unsealObject = (Serializable) sealedObject.getObject(cipher);
+        return unsealObject;
+    }
+
+    public static String encryptPasswordBased(String plainText, SecretKey key, IvParameterSpec iv)
+            throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidAlgorithmParameterException,
+            InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
+        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
+        cipher.init(Cipher.ENCRYPT_MODE, key, iv);
+        return Base64.getEncoder()
+                .encodeToString(cipher.doFinal(plainText.getBytes()));
+    }
+
+    public static String decryptPasswordBased(String cipherText, SecretKey key, IvParameterSpec iv)
+            throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidAlgorithmParameterException,
+            InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
+        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
+        cipher.init(Cipher.DECRYPT_MODE, key, iv);
+        return new String(cipher.doFinal(Base64.getDecoder()
+                .decode(cipherText)));
+    }
+
+}

src/main/java/org/qortal/utils/ZipUtils.java

@@ -1,8 +1,25 @@
 /*
  * MIT License
+ *
  * Copyright (c) 2017 Eugen Paraschiv
  *
- * Based on code taken from: https://github.com/eugenp/tutorials/tree/master/core-java-modules/core-java-io/src/main/java/com/baeldung
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
  *
  */