java对称加密算法

谁践踏了优雅 2022-06-15 04:16 359阅读 0赞

> 慕课网学习笔记  
> 参考：[Java加密算法][Java]

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*   *  对称加密算法
        
         *  对称加密算法 DES
         *  对称加密算法3重DES
         *  对称加密算法AES
         *  对称加密算法PBE

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## 对称加密算法 ##

加密密钥和解密密钥相同，加密运算和解密运算互为逆运算。是一种初等的加密算法。主要的算法有DES（3DES）、AES、PBE、IDEA。

### 对称加密算法 —— DES ###

数据加密标准（Data Encryption Standard），IBM提交的算法。  
![这里写图片描述][291403564588948.jpg]

package des;
    
    import java.security.Security;
    
    import javax.crypto.Cipher;
    import javax.crypto.KeyGenerator;
    import javax.crypto.SecretKey;
    import javax.crypto.SecretKeyFactory;
    import javax.crypto.spec.DESKeySpec;
    
    import org.apache.commons.codec.binary.Hex;
    import org.bouncycastle.jce.provider.BouncyCastleProvider;
    
    public class JavaDES { 
    
        private static String src = "面向对象编程，object-oriented！@#*5"; // 需要加密的原始字符串
    
        public static void main(String[] args) throws Exception {
            System.out.println("原始字符串：\n" + src);
            jdkDES();
            bouncyCastleDES();
        }
    
        /** jdk实现DES加密 */
        public static void jdkDES() throws Exception{
    
            //1.生成key
            KeyGenerator keyGenerator = KeyGenerator.getInstance("des");//密钥生成器
            keyGenerator.init(56);//指定密钥长度为56位
            SecretKey secretKey = keyGenerator.generateKey();//用密钥生成器生成密钥
            byte[] byteKeys = secretKey.getEncoded();//得到密钥的byte数组
    
            //2.key转换
            DESKeySpec desKeySpec = new DESKeySpec(byteKeys);
            SecretKeyFactory factory = SecretKeyFactory.getInstance("des");//秘密密钥工厂
            SecretKey convertSecretKey = factory.generateSecret(desKeySpec);
    
            //3.加密
            Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");//见上图的工作模式和填充模式
            cipher.init(Cipher.ENCRYPT_MODE, convertSecretKey);//加密模式
            byte[]result = cipher.doFinal(src.getBytes());
    
            System.out.println("jdk DES加密：\n" + Hex.encodeHexString(result));
    
            //4.解密
            cipher.init(Cipher.DECRYPT_MODE, convertSecretKey);//解密模式
            result = cipher.doFinal(result);
            System.out.println("jdk DES解密：\n" + new String(result));
        }
    
        /** Bouncy Castle实现DES加密 */
        public static void bouncyCastleDES() throws Exception{
    
            Security.addProvider(new BouncyCastleProvider());//增加provider
    
            //1.生成key
            KeyGenerator keyGenerator = KeyGenerator.getInstance("des","BC");//密钥生成器，指定为bouncyCastle默认是sun的JCE
            keyGenerator.init(56);//指定key长度为56位
            keyGenerator.getProvider();
            SecretKey secretKey = keyGenerator.generateKey();//用密钥生成器生成密钥
            byte[] byteKeys = secretKey.getEncoded();//得到密钥的byte数组
    
            //2.key转换
            DESKeySpec desKeySpec = new DESKeySpec(byteKeys);
            SecretKeyFactory factory = SecretKeyFactory.getInstance("des");//密钥工厂
            SecretKey convertSecretKey = factory.generateSecret(desKeySpec);
    
            //3.加密
            Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
            cipher.init(Cipher.ENCRYPT_MODE, convertSecretKey);//加密模式
            byte[]result = cipher.doFinal(src.getBytes());
    
            System.out.println("bc DES加密：\n" + Hex.encodeHexString(result));
    
            //4.解密
            cipher.init(Cipher.DECRYPT_MODE, convertSecretKey);//解密模式
            result = cipher.doFinal(result);
            System.out.println("bc DES解密：\n" + new String(result));
        }
    }

运行结果：  
![这里写图片描述][291457445206207.jpg]

在使用bc进行DES加解密的时候除了需要使用Security.addProvider()方法增加一个BouncyCastle，还需要指定密钥生成器的提供者为BC，如上面的代码的57行，否则会默认使用sun的JCE。应用场景：

![这里写图片描述][291501119279203.jpg]

### 对称加密算法——3重DES ###

3DES的好处是密钥长度增加。迭代次数增加。  
![这里写图片描述][291505115679182.jpg]

实现的方式通常由JDK和BC两种，实现的方式和DES的实现方式大同小异：

package des;
    
    import java.security.SecureRandom;
    import java.security.Security;
    
    import javax.crypto.Cipher;
    import javax.crypto.KeyGenerator;
    import javax.crypto.SecretKey;
    import javax.crypto.SecretKeyFactory;
    import javax.crypto.spec.DESedeKeySpec;
    
    import org.apache.commons.codec.binary.Hex;
    import org.bouncycastle.jce.provider.BouncyCastleProvider;
    
    public class Java3DES { 
    
        private static String src = "面向对象编程，object-oriented！@#*5"; // 需要加密的原始字符串
    
        public static void main(String[] args) throws Exception {
            System.out.println("原始字符串：" + src + "\n");
            jdk3DES();
            bouncyCastle3DES();
        }
    
        /** jdk实现3DES */
        public static void jdk3DES() throws Exception{
            //1.生成key
            KeyGenerator keyGenerator = KeyGenerator.getInstance("desede");//密钥生成器
    // keyGenerator.init(new SecureRandom()); //可以用它生成一个默认长度的key
            keyGenerator.init(168);//指定密钥长度为112位
            SecretKey secretKey = keyGenerator.generateKey();//用密钥生成器生成密钥
            byte[] byteKeys = secretKey.getEncoded();//得到密钥的byte数组
    
            //2.key转换
            DESedeKeySpec deSedeKeySpec = new DESedeKeySpec(byteKeys);
            SecretKeyFactory factory = SecretKeyFactory.getInstance("desede");//秘密密钥工厂
            SecretKey convertSecretKey = factory.generateSecret(deSedeKeySpec);
    
            //3.加密
            Cipher cipher = Cipher.getInstance("desede/ECB/PKCS5Padding");
            cipher.init(Cipher.ENCRYPT_MODE, convertSecretKey);//加密模式
            byte[]result = cipher.doFinal(src.getBytes());
    
            System.out.println("jdk DES3加密：\n" + Hex.encodeHexString(result));
    
            //4.解密
            cipher.init(Cipher.DECRYPT_MODE, convertSecretKey);//解密模式
            result = cipher.doFinal(result);
            System.out.println("jdk DES3解密：\n" + new String(result) + "\n");
        }
    
        /** bc实现3DES */
        public static void bouncyCastle3DES() throws Exception{
    
            Security.addProvider(new BouncyCastleProvider());
    
            //1.生成key
            KeyGenerator keyGenerator = KeyGenerator.getInstance("desede","BC");//密钥生成器[指定provider]
            keyGenerator.init(new SecureRandom());//指定密钥的长度为默认
            SecretKey secretKey = keyGenerator.generateKey();//用密钥生成器生成密钥
            byte[] byteKeys = secretKey.getEncoded();//得到密钥的byte数组
    
            //2.key转换
            DESedeKeySpec deSedeKeySpec = new DESedeKeySpec(byteKeys);
            SecretKeyFactory factory = SecretKeyFactory.getInstance("desede");//秘密密钥工厂
            SecretKey convertSecretKey = factory.generateSecret(deSedeKeySpec);
    
            //3.加密
            Cipher cipher = Cipher.getInstance("desede/ECB/PKCS5Padding");
            cipher.init(Cipher.ENCRYPT_MODE, convertSecretKey);//加密模式
            byte[]result = cipher.doFinal(src.getBytes());
    
            System.out.println("bc DES3加密：\n" + Hex.encodeHexString(result));
    
            //4.解密
            cipher.init(Cipher.DECRYPT_MODE, convertSecretKey);//解密模式
            result = cipher.doFinal(result);
            System.out.println("bc DES3解密：\n" + new String(result) + "\n");
    
        }
    }

运行结果：  
![这里写图片描述][291540439745610.jpg]

### 对称加密算法——AES ###

AES产生的原因是3重DES的效率比较低而DES的安全性较低。AES是目前使用最多的对称加密算法，AES还有一个优势是至今尚未被破解。AES通常用于移动通信系统的加密以及基于SSH协议的软件（SSH Client、SecurityCRT）的加密。密钥长度以及实现方如下：  
![这里写图片描述][291831010997965.jpg]

无政策限制权限文件是指：因为某些国家的进口管制限制，java发布的运行环境包中的一些加解密有一定的限制（因为美国政府的一些原因）。一般的JDK的jre的security包中的local\_policy.jar和US\_export\_policy.jar都是没有内容的，所以只能使用128位加密。下面是JDK和BC实现的AES加密（步骤和DES类似）：

package aes;
    
    import java.security.Key;
    import java.security.Security;
    
    import javax.crypto.Cipher;
    import javax.crypto.KeyGenerator;
    import javax.crypto.SecretKey;
    import javax.crypto.spec.SecretKeySpec;
    
    import org.apache.commons.codec.binary.Base64;
    import org.bouncycastle.jce.provider.BouncyCastleProvider;
    
    public class JavaAES {
    
        private static String src = "面向对象编程，object-oriented！@#*5"; // 需要加密的原始字符串
    
        public static void main(String[] args) throws Exception {
            System.out.println("初始字符串:" + src + "\n");
            jdkAES();
            bouncyCastleAES();
        }
    
        public static void jdkAES() throws Exception{
    
            //1.生成key
            KeyGenerator keyGenerator = KeyGenerator.getInstance("aes");
            keyGenerator.init(128);//初始化key的长度，只能是128，
            SecretKey secretKey = keyGenerator.generateKey();//生成key
            byte[] keyBytes = secretKey.getEncoded();//得到key的字节数组
    
            //2.key的转换
            Key key = new SecretKeySpec(keyBytes, "aes");
    
            //3.加密
            Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");//加解密方式+工作模式+填充方式
            cipher.init(Cipher.ENCRYPT_MODE, key);//以加密模式初始化
            byte[] result = cipher.doFinal(src.getBytes());
            System.out.println("JDK AES加密：" + Base64.encodeBase64String(result));
    
            //4.解密
            cipher.init(Cipher.DECRYPT_MODE, key);
            result = cipher.doFinal(result);
            System.out.println("JDK AES解密：" + new String(result));
        }
    
        public static void bouncyCastleAES() throws Exception{
    
            Security.addProvider(new BouncyCastleProvider());
            KeyGenerator keyGenerator = KeyGenerator.getInstance("aes", "BC");
            keyGenerator.init(128);//这里只能指定128，不能使用keyGenerator.init(new SecureRandom())
            SecretKey secretKey = keyGenerator.generateKey();
            byte[] keyBytes = secretKey.getEncoded();
    
            Key key = new SecretKeySpec(keyBytes, "aes");
    
            Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5padding");
            cipher.init(Cipher.ENCRYPT_MODE, key);
            byte[] result = cipher.doFinal(src.getBytes());
            System.out.println("bc AES加密：" + Base64.encodeBase64String(result));
    
            cipher.init(Cipher.DECRYPT_MODE, key);
            result = cipher.doFinal(result);
            System.out.println("bc AES解密：" + new String(result));
        }
    }

运行结果：  
![这里写图片描述][291917333956929.jpg]

### 对称加密算法——PBE ###

PBE算法结合了消息摘要算法和对称加密算法的优点，是一种特殊的对称加密算法。Password Based Encryption，基于口令的加密。因为口令是比较好记的，就容易通过穷举、猜测的方式获得口令——针对这种情况，我们采用的方式是加盐（Salt），通过加入一些额外的内容（通常是随机字符）去扰乱。实现的方式有2种：JDK和BC。  
![这里写图片描述][291932371771572.jpg]

![这里写图片描述][291927440838097.jpg]

JDK和BC实现的PBEWithMD5AndDES的算法如下：

package pbe;
    
    import java.security.Key;
    import java.security.SecureRandom;
    import java.security.Security;
    
    import javax.crypto.Cipher;
    import javax.crypto.SecretKeyFactory;
    import javax.crypto.spec.PBEKeySpec;
    import javax.crypto.spec.PBEParameterSpec;
    
    import org.apache.commons.codec.binary.Base64;
    import org.bouncycastle.jce.provider.BouncyCastleProvider;
    
    public class JavaPBE {
    
        private static String src = "面向对象编程，object-oriented！@#*5"; // 需要加密的原始字符串
    
        public static void main(String[] args) throws Exception {
            System.out.println("原始字符串：" + src);
            jdkPBE();
            bouncyCastlePBE();
        }
    
        public static void jdkPBE() throws Exception{
    
            //1.初始化盐
            SecureRandom secureRandom = new SecureRandom();//强加密随机数生成器
            byte[] salt= secureRandom.generateSeed(8);//产生盐必须是8位
    
            //2.口令与密钥
            String password = "root";
            PBEKeySpec pbeKeySpec = new PBEKeySpec(password.toCharArray());//密钥转换的对象
            SecretKeyFactory factory = SecretKeyFactory.getInstance("PBEWithMD5AndDES");//实例化密钥转换工厂
            Key key = factory.generateSecret(pbeKeySpec);//由工厂产生key
    
            //3.加密
            PBEParameterSpec parameterSpec = new PBEParameterSpec(salt, 100);//PBE输入参数的材料，盐，迭代100次
            Cipher cipher = Cipher.getInstance("PBEWithMD5AndDES");
            cipher.init(Cipher.ENCRYPT_MODE, key, parameterSpec);
            byte[] result = cipher.doFinal(src.getBytes());
            System.out.println("jdk PBE加密：" + Base64.encodeBase64String(result));
    
            //4.解密
            cipher.init(Cipher.DECRYPT_MODE, key, parameterSpec);
            result = cipher.doFinal(result);
            System.out.println("jdk PBE解密：" + new String(result));
        }
    
        public static void bouncyCastlePBE() throws Exception{
    
            Security.addProvider(new BouncyCastleProvider());//添加到provider
    
            SecureRandom secureRandom = new SecureRandom();
            byte[] salt = secureRandom.generateSeed(8);
    
            String password = "admin";
            PBEKeySpec pbeKeySpec = new PBEKeySpec(password.toCharArray());
            SecretKeyFactory factory = SecretKeyFactory.getInstance("PBEWithMD5AndDES","BC");//指定provider
            Key key = factory.generateSecret(pbeKeySpec);
    
            PBEParameterSpec parameterSpec = new PBEParameterSpec(salt, 50);
            Cipher cipher = Cipher.getInstance("PBEWithMD5AndDES");
            cipher.init(Cipher.ENCRYPT_MODE, key,parameterSpec);
            byte[]result = cipher.doFinal(src.getBytes());
    
            System.out.println("bc PBE加密：" + Base64.encodeBase64String(result));
    
            cipher.init(Cipher.DECRYPT_MODE, key, parameterSpec);
            result = cipher.doFinal(result);
            System.out.println("bc PBE解密：" + new String(result));
        }
    }

应用场景：  
![这里写图片描述][292030015367577.jpg]

[Java]: http://www.cnblogs.com/happyfans/p/4374919.html
[291403564588948.jpg]: /images/20220615/00092605a2ec42118723e77aa1e2c7fa.png
[291457445206207.jpg]: /images/20220615/7f186fd1be994f2180d136f73dbaa3a8.png
[291501119279203.jpg]: /images/20220615/a5d4f48e0e724ac19bf480b650b4c420.png
[291505115679182.jpg]: /images/20220615/a94c67e6c42a4938b21045cdc8928144.png
[291540439745610.jpg]: /images/20220615/97582fecd3784c7ea789e021a26bf11a.png
[291831010997965.jpg]: /images/20220615/dfbce63b6fff47de87bf86e72091ca3f.png
[291917333956929.jpg]: /images/20220615/060f913282854ebbb57151e086137fa4.png
[291932371771572.jpg]: /images/20220615/ceaf7bc4d6ec46b8a9a8b22dc011ebe0.png
[291927440838097.jpg]: /images/20220615/a9cc0894087141b6b0c52f2ef1dc7345.png
[292030015367577.jpg]: /images/20220615/64af6df08146409b925feacb7d288f79.png