加密算法使用（四）：AES的使用

AES是一种对称加密方式，比DES更为安全，用一个秘钥加密数据之后，可以用同一个秘钥对加密后的数据解密还原，以下是一套以字符串为例子的使用全过程演示，

用到了

commons-codec.jar

package testEncrypt;

import java.security.InvalidKeyException;
import java.security.Key;
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 javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.Base64;
//import sun.misc.BASE64Encoder;
public class TestAesEncrypt {

    public static void main(String[] args) throws NoSuchAlgorithmException, InvalidKeyException, NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException {
        //随机生成密钥
        KeyGenerator keygen = KeyGenerator.getInstance("AES");
        //SecureRandom random = new SecureRandom(Base64.decodeBase64("abc"));
        SecureRandom random = new SecureRandom();
        keygen.init(random);
        Key key = keygen.generateKey();
        //获取秘钥字符串
        String key64Str = Base64.encodeBase64String(key.getEncoded());
        //要加密的数据
        String dataStr="da89gh9qj3ebg9babjdslgbuqgb&FTUG^(GB";
        System.out.println("要加密的数据："+dataStr);
        
        //还原秘钥字符串到秘钥byte数组
        byte[] keyByteArray = Base64.decodeBase64(key64Str);
        //重新形成秘钥，SecretKey是Key的子类
        SecretKey secretKey = new SecretKeySpec(keyByteArray, "AES");
        
        //初始化加密组件
        Cipher cipher = Cipher.getInstance("AES");  
        cipher.init(Cipher.ENCRYPT_MODE, secretKey);  
        
        //加密后的数据，首先将字符串转为byte数组，然后加密，为便于保存先转为base64
        String encryptedDataStr = Base64.encodeBase64String(cipher.doFinal(dataStr.getBytes()));
        System.out.println("加密后的数据："+encryptedDataStr);
        
        //将加密组件的模式改为解密
        cipher.init(Cipher.DECRYPT_MODE, secretKey); 
         //和上面的加密相反，先解base64，再解密，最后将byte数组转为字符串
         String decodeDataStr = new String(cipher.doFinal(Base64.decodeBase64(encryptedDataStr)));
         System.out.println("解密后的数据："+decodeDataStr);
    }

}