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AJAXJS aims to full-stack, not only the server-side framework, but also integrates the front-end library. It's written in HTML5 + Java, a successor to the JVM platform, efficient, secure, stable, cross-platform and many other advantages, but it abandoned the traditional enterprise architecture brought about by the large and bloated, emphasizing the lightweight, and fast, very suitable for the Internet fast application.

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/**
 * Copyright 2015 Sp42 [email protected]
 *
 * 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 com.ajaxjs.util.cryptography;

import java.nio.charset.StandardCharsets;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;

import com.ajaxjs.util.Encode;

/**
 * 对称算法
 * 
 * @author Sp42 [email protected]
 *
 */
public class SymmetricCipher {
	public SymmetricCipher() {
	}

	/**
	 * 创建一个 SymmetricCipher
	 * 
	 * @param ALGORITHM 加密算法，可以 DES | AES
	 * @param keySize   DES = 56 | AES = 128
	 */
	public SymmetricCipher(String ALGORITHM, int keySize) {
		this.ALGORITHM = ALGORITHM;
		this.keySize = keySize;
	}

	/**
	 * DES = 56 | AES = 128
	 */
	private int keySize = 128;

	/**
	 * 加密算法，可以 DES | AES
	 */
	private String ALGORITHM = "AES";

	/**
	 * 加密
	 * 
	 * @param str 要加密的内容
	 * @param key 密钥
	 * @return 加密后的内容
	 */
	public String encrypt(String str, String key) {
		// (这里要设置为utf-8)不然内容中如果有中文和英文混合中文就会解密为乱码
		return doCipher(true, key, str.getBytes(StandardCharsets.UTF_8));
	}

	/**
	 * 解密
	 * 
	 * @param str 要解密的内容
	 * @param key 密钥
	 * @return 解密后的内容
	 */
	public String decrypt(String str, String key) {
		return doCipher(false, key, Encode.base64DecodeAsByte(str));
	}

	/**
	 * 
	 * @param isENCRYPT_MODE true加密/false=解密
	 * @param key            密钥
	 * @param bytes          加密/解密的内容
	 * @return 结果
	 */
	private String doCipher(boolean isENCRYPT_MODE, String key, byte[] bytes) {
		Cipher cipher = null;

		try {
			cipher = Cipher.getInstance(ALGORITHM);
			cipher.init(isENCRYPT_MODE ? Cipher.ENCRYPT_MODE : Cipher.DECRYPT_MODE, generateKey(key));
		} catch (NoSuchAlgorithmException | InvalidKeyException | NoSuchPaddingException e) {
			e.printStackTrace();
			return null;
		}

		byte[] buf;
		try {
			// 为了防止解密时报javax.crypto.IllegalBlockSizeException: Input length must
			// be multiple of 8 when decrypting with padded cipher异常，
			// 不能把加密后的字节数组直接转换成字符串
			buf = cipher.doFinal(bytes);
		} catch (IllegalBlockSizeException | BadPaddingException e) {
			e.printStackTrace();
			return null;
		}

		return isENCRYPT_MODE ? Encode.base64Encode(buf) : Encode.byte2String(buf);
	}

	/**
	 * 获得密钥对象
	 * 
	 * @param key 密钥
	 * @return 密钥对象
	 */
	private SecretKey generateKey(String key) {
		SecureRandom secureRandom;
		KeyGenerator kg;

		try {
			secureRandom = SecureRandom.getInstance("SHA1PRNG");
			secureRandom.setSeed(key.getBytes());
			kg = KeyGenerator.getInstance(ALGORITHM);
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
			return null;
		}

		kg.init(keySize, secureRandom);
		return kg.generateKey();// 生成密钥
	}

	final static SymmetricCipher AES = new SymmetricCipher();
	final static SymmetricCipher DES = new SymmetricCipher("DES", 56);

	/**
	 * AES 加密
	 * 
	 * @param str 要加密的内容
	 * @param key 密钥
	 * @return 加密后的内容
	 */
	public static String AES_Encrypt(String str, String key) {
		return AES.encrypt(str, key);
	}

	/**
	 * AES 解密
	 * 
	 * @param str 要解密的内容
	 * @param key 密钥
	 * @return 加密后的内容
	 */
	public static String AES_Decrypt(String str, String key) {
		return AES.decrypt(str, key);
	}
}