EncryptionUtil.java

/*
 * Copyright (c) 2014-2015 Janith Bandara, This source is a part of
 * Audit4j - An open source auditing framework.
 * http://audit4j.org
 *
 * 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 org.audit4j.core.util;

import java.io.UnsupportedEncodingException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;

import org.audit4j.core.CoreConstants;
import org.audit4j.core.handler.ConsoleAuditHandler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * The Class SecurityUtil.
 * 
 * @author <a href="mailto:janith3000@gmail.com">Janith Bandara</a>
 * 
 * @since 1.0.2
 */
public class EncryptionUtil {

    /** The log. */
    private static final Logger LOG = LoggerFactory.getLogger(ConsoleAuditHandler.class);

    /** The Constant ALGORYITHM. */
    private static final String ALGORYITHM = "AES/CBC/PKCS5Padding";

    /** The instance. */
    private static EncryptionUtil instance;

    /** The crypt key. */
    private static Key cryptKey;

    /**
     * Instantiates a new encrypt util.
     */
    private EncryptionUtil() {
    }

    /**
     * Encrypt.
     *
     * @param raw the raw
     * @return the string
     * @throws IllegalBlockSizeException the illegal block size exception
     * @throws BadPaddingException the bad padding exception
     * @throws UnsupportedEncodingException the unsupported encoding exception
     * @throws InvalidKeyException the invalid key exception
     * @throws InvalidAlgorithmParameterException the invalid algorithm parameter exception
     * @throws NoSuchAlgorithmException the no such algorithm exception
     * @throws NoSuchPaddingException the no such padding exception
     */
    public String encrypt(String raw) throws IllegalBlockSizeException, BadPaddingException,
            UnsupportedEncodingException, InvalidKeyException, InvalidAlgorithmParameterException,
            NoSuchAlgorithmException, NoSuchPaddingException {
        Cipher c = getCipher(Cipher.ENCRYPT_MODE);

        byte[] encryptedVal = c.doFinal(raw.getBytes(CoreConstants.ENCODE_UTF8));
        return new String(Base64Coder.encode(encryptedVal));
    }

    /**
     * Decrypt.
     * 
     * @param encrypted
     *            the encrypted
     * @return the string
     * @throws Exception
     *             the exception
     */
    public String decrypt(String encrypted) throws Exception {

        byte[] decodedValue = Base64Coder.decode(encrypted.toCharArray());

        Cipher c = getCipher(Cipher.DECRYPT_MODE);
        byte[] decValue = c.doFinal(decodedValue);

        return new String(decValue);
    }

    /**
     * Gets the cipher.
     *
     * @param mode the mode
     * @return the cipher
     * @throws InvalidKeyException the invalid key exception
     * @throws InvalidAlgorithmParameterException the invalid algorithm parameter exception
     * @throws UnsupportedEncodingException the unsupported encoding exception
     * @throws NoSuchAlgorithmException the no such algorithm exception
     * @throws NoSuchPaddingException the no such padding exception
     */
    private Cipher getCipher(int mode) throws InvalidKeyException, InvalidAlgorithmParameterException,
            UnsupportedEncodingException, NoSuchAlgorithmException, NoSuchPaddingException {
        Cipher c = Cipher.getInstance(ALGORYITHM);

        byte[] iv = CoreConstants.IV.getBytes(CoreConstants.ENCODE_UTF8);

        c.init(mode, cryptKey, new IvParameterSpec(iv));
        return c;
    }

    /**
     * Generate key.
     * 
     * @param key
     *            the key
     * @param salt
     *            the salt
     * @return the key
     * @throws NoSuchAlgorithmException
     *             the no such algorithm exception
     * @throws UnsupportedEncodingException
     *             the unsupported encoding exception
     * @throws InvalidKeySpecException
     *             the invalid key spec exception
     */
    private static void generateKeyIfNotAvailable(String key, String salt) throws NoSuchAlgorithmException,
            UnsupportedEncodingException, InvalidKeySpecException {
        if (null == cryptKey) {
            LOG.debug("Generating Key...");
            SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
            char[] password = key.toCharArray();
            byte[] saltBytes = salt.getBytes(CoreConstants.ENCODE_UTF8);

            KeySpec spec = new PBEKeySpec(password, saltBytes, 65536, 128);
            SecretKey tmp = factory.generateSecret(spec);
            byte[] encoded = tmp.getEncoded();
            cryptKey = new SecretKeySpec(encoded, "AES");
        }
    }

    /**
     * Gets the Encryptor.
     *
     * @param key the key
     * @param salt the salt
     * @return the Encryptor
     * @throws NoSuchAlgorithmException the no such algorithm exception
     * @throws UnsupportedEncodingException the unsupported encoding exception
     * @throws InvalidKeySpecException the invalid key spec exception
     */
    public static EncryptionUtil getInstance(String key, String salt) throws NoSuchAlgorithmException,
            UnsupportedEncodingException, InvalidKeySpecException {
        if (instance == null) {
            synchronized (EncryptionUtil.class) {
                if (instance == null) {
                    instance = new EncryptionUtil();
                    generateKeyIfNotAvailable(key, salt);
                }
            }
        }
        return instance;
    }
}