信息加密之对称加密算法

　　对于信息的加密方式多种多样，之前为大家介绍了一种自己设计的加密方式，有兴趣的朋友可以欣赏一下，欢迎给予指点。今天为大家介绍一下对称加密方式，所谓对称加密指的是加密和解密方式呈对称格式，即解密是加密的逆过程，下面我们就看一下：DES、3DES、AES、PBE这四种方式，他们的加密强度依次递增。好吧闲话少说，上代码：

首先我们先看一下DES：

package cn.edu.hpu.des;

import java.security.Key;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;

public class jdk_DES {
    private static final String src = "I Love You !";
    public static void main(String [] args){
        jdk_DES.jdkDES();
    }
    @SuppressWarnings("static-access")
    public static void jdkDES(){
        try {
            //获得KEY
            KeyGenerator keyGenerator = KeyGenerator.getInstance("DES");
            keyGenerator.init(56);//设置为默认值56即可
            //获得KEY对象
            SecretKey secrekeyone = keyGenerator.generateKey();
            byte [] byteskey = secrekeyone.getEncoded();
            
            //KEY转换
            DESKeySpec deskeyspec = new DESKeySpec(byteskey);
            SecretKeyFactory factory = SecretKeyFactory.getInstance("DES");
            Key secerkeytwo = factory.generateSecret(deskeyspec);
            
            //加密
            Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
            cipher.init(cipher.ENCRYPT_MODE, secerkeytwo);//设置模式为加密
            byte[] result = cipher.doFinal(src.getBytes());
            System.out.println("jdkEDS:"+result.toString());
            
            //解密
            cipher.init(cipher.DECRYPT_MODE, secerkeytwo);//设置模式为解密
            result = cipher.doFinal(result);
            System.out.println("jdkEDS:"+new String(result));
            
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

运行结果：

第二种3重DES:

package cn.edu.hpu.des;

import java.security.Key;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;

public class jdk_3DES {
    private static final String src = "I Love You !";
    public static void main(String [] args){
        jdk_3DES.jdk3DES();
    }
    @SuppressWarnings("static-access")
    public static void jdk3DES(){
        try {
            //获得KEY
            KeyGenerator keyGenerator = KeyGenerator.getInstance("DESede");
            //keyGenerator.init(112);//设置密钥长度，默认值为168，也可设置为112
            keyGenerator.init(new SecureRandom());//设置为默认值
            //获得KEY对象
            SecretKey secrekeyone = keyGenerator.generateKey();
            byte [] byteskey = secrekeyone.getEncoded();
            
            //KEY转换
            DESKeySpec deskeyspec = new DESKeySpec(byteskey);
            SecretKeyFactory factory = SecretKeyFactory.getInstance("DES");
            Key secerkeytwo = factory.generateSecret(deskeyspec);
            
            //加密
            Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
            cipher.init(cipher.ENCRYPT_MODE, secerkeytwo);//设置模式为加密
            byte[] result = cipher.doFinal(src.getBytes());
            System.out.println("jdkEDS:"+result.toString());
            
            //解密
            cipher.init(cipher.DECRYPT_MODE, secerkeytwo);//设置模式为解密
            result = cipher.doFinal(result);
            System.out.println("jdkEDS:"+new String(result));
            
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

运行结果：

第三种AES:

package cn.edu.hpu.aes;

import java.security.Key;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class jdk_AES {
    private static final String src = "I Love You !";
    public static void main(String [] args){
        AES();
    }
    public static void AES(){
        try {
            //获得key
            KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
            keyGenerator.init(new SecureRandom());//默认密钥长度为：
            SecretKey secretKey = keyGenerator.generateKey();
            byte [] keyBytes = secretKey.getEncoded();
            
            //key转换
            Key key = new SecretKeySpec(keyBytes, "AES");
            
            //加密
            Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
            cipher.init(Cipher.ENCRYPT_MODE, key);
            byte[] result = cipher.doFinal(src.getBytes());
            System.out.println("AES="+result.toString());
            
            //解密
            cipher.init(Cipher.DECRYPT_MODE, key);
            result = cipher.doFinal(result);
            System.out.println("AES="+new String(result));
            
        } catch (Exception e) {
            e.printStackTrace();
        }    
    }
}

运行结果：

最后一种PBE:

package cn.edu.hpu.pbe;

import java.security.Key;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;

public class jdk_PBE {
    public static final String src = "I Love You !";
    public static void main(String [] args){
        jdkPBE();
    }
    private static void jdkPBE(){
        try {
            //初始化盐
            SecureRandom random = new SecureRandom();
            byte [] salt = random.generateSeed(8);
            
            //口令和密钥
            String password = "imooc";
            PBEKeySpec pbeKeySpec = new PBEKeySpec(password.toCharArray());//生成密钥转换对象
            SecretKeyFactory factory = SecretKeyFactory.getInstance("PBEWITHMD5andDES");
            Key key = factory.generateSecret(pbeKeySpec);
            
            //加密
            PBEParameterSpec pbeParameterSpec = new PBEParameterSpec(salt, 100);//实例化PBE对象的一个输入的材料：参数分别为"盐和迭代次数"
            Cipher cipher = Cipher.getInstance("PBEWITHMD5andDES");
            cipher.init(Cipher.ENCRYPT_MODE, key, pbeParameterSpec);
            byte [] result = cipher.doFinal(src.getBytes());
            System.out.println("PBE:"+result.toString());
            
            //解密
            cipher.init(Cipher.DECRYPT_MODE, key, pbeParameterSpec);
            result = cipher.doFinal(result);
            System.out.println("PBE:"+new String(result));
            
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

运行结果：

　　对于以上四种方式，PBE是一种较安全的加密方式，对加密起绝定作用的是盐和password，决定着加密的结果。以上即使要为大家介绍的对称加密方式，哪位有更好的方式，还望指教。