AESOperator.java

import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.Security;
import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.util.Arrays;
import org.bouncycastle.util.encoders.Hex;

/**
 *
 * @author lhl AES128 算法
 *
 *         CBC 模式
 *
 *         PKCS7Padding 填充模式
 *
 *         CBC模式需要添加一个参数iv
 *
 *         介于java 不支持PKCS7Padding，只支持PKCS5Padding 但是PKCS7Padding 和 PKCS5Padding
 *         没有什么区别 要实现在java端用PKCS7Padding填充，需要用到bouncycastle组件来实现
 */
public class AESOperator {
	// 算法名称
	final String KEY_ALGORITHM = "AES";
	// 加解密算法/模式/填充方式
	final String algorithmStr = "AES/CBC/PKCS7Padding";
	//
	private Key key;
	private Cipher cipher;
	boolean isInited = false;

	//偏移iv 16位的16进制的ASCII码，我这里示例的iv是ABCDEF1234123412，密钥在创建实例时定义
	byte[] iv = { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46,0x31, 0x32, 0x33, 0x34, 0x31, 0x32, 0x33, 0x34, 0x31, 0x32 };
	
	public void init(byte[] keyBytes) {

		// 如果密钥不足16位，那么就补足. 这个if 中的内容很重要
		int base = 16;
		if (keyBytes.length % base != 0) {
			int groups = keyBytes.length / base + (keyBytes.length % base != 0 ? 1 : 0);
			byte[] temp = new byte[groups * base];
			Arrays.fill(temp, (byte) 0);
			System.arraycopy(keyBytes, 0, temp, 0, keyBytes.length);
			keyBytes = temp;
		}
		// 初始化
		Security.addProvider(new BouncyCastleProvider());
		// 转化成JAVA的密钥格式
		key = new SecretKeySpec(keyBytes, KEY_ALGORITHM);
		try {
			// 初始化cipher
			cipher = Cipher.getInstance(algorithmStr, "BC");
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (NoSuchPaddingException e) {
			e.printStackTrace();
		} catch (NoSuchProviderException e) {
			e.printStackTrace();
		}
	}


	/**
	 * 解密方法
	 *
	 * @param encryptedData
	 *            要解密的字符串
	 * @param keyBytes
	 *            解密密钥
	 * @return
	 */
	public byte[] decrypt(String encryptedData, byte[] keyBytes) {
		byte[] encryptedText = null;
		init(keyBytes);
		try {
			cipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(iv));
			//将前端传来的加密数据转换成此方法需要的类型
			byte[] DataByte = Hex.decode(encryptedData);
			//解密
			encryptedText = cipher.doFinal(DataByte);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return encryptedText;
	}


	//附上一个后台java使用的示例
	public static void main(String[] args) {
		//设置AES加密的密钥 16位的16进制的ASCII码，我这里示例是1234123412ABCDEF
		byte[] keybytes = { 0x31, 0x32, 0x33, 0x34, 0x31, 0x32, 0x33, 0x34, 0x31, 0x32, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46 };
		//AES创建实例
		AESOperator aes = new AESOperator();

		//假设data是前端传来加密过的数据，不分大小写
		String data = "b59227d86200d7fedfb8418a59a8eea9";

		//解密并输出
		System.Out.println(new String( aes.decrypt(data,keybytes)));

	}
}