（黑马）总结一：Java 加密解密简单例子

在Java的加密和解密，有两种区分。一种被称作为对称加密。就是加密者和解密者都要知道一个固定密码。加入加密者，加密密码为123456.那么解密者就必须知道这个密码，以作为解密的时候使用的密码。说点白话，就是密码要一致。就是对称加密。当然也可以不知道密码，我们日常的电子银行中的U盾，其实就是一个密码。只不过保存在制定文件种了。

不对称加密，就是我们有一个公共的加密方式，大家都是知道的并按照这个规范来我加密。但是只有一个人才可以解密。而且解密的密码是一个。这样的加密方式，我们在给银行发送数据的时候使用。因为我们发送的信息，使用了银行的统一的加密方式来加密，而且能够解密的密码，也只有银行拥有。这样就保证了我们发送的数据不会被别人恶意的截取。即使截取了他也没有办法看明白我们发送的数据。

package cn.csdn.hm;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.ObjectInputStream;import java.io.ObjectOutputStream;import java.security.Key;import java.security.KeyPair;import java.security.KeyPairGenerator;import java.security.PrivateKey;import java.security.PublicKey;import java.security.Signature;import javax.crypto.Cipher;import javax.crypto.KeyGenerator;import javax.crypto.SecretKey;import javax.crypto.SecretKeyFactory;import javax.crypto.spec.PBEKeySpec;import javax.crypto.spec.PBEParameterSpec;public class NewMyCipher {/** * @param args */public static void main(String[] args) throws Exception {// 對稱加密// myDncrypt();// 對稱解密// myEncrpt();// 非对称的加密// mySecretPariEncrypt();// 非对称解密 //mySecretPairDncrypt();// 對稱加密 根據用戶提供的密碼，來進行加密解密，雙方只是知道密碼。 这个密码的长度只能是8的倍数这点需要注意 //otherMySecretEncrypt("12345679");//對稱解密//otherMySecretDncrypt("12345679");//数字签名//mySignatureToByte();//验证数字签名//mySignatureVerify();}@SuppressWarnings("unused")private static void mySignatureVerify()throws Exception {PublicKey publicKey=(PublicKey) readerKey("mySignaturePublicKey.key");Signature signature=Signature.getInstance("MD5withRSA");signature.initVerify(publicKey);signature.update(readerDat("src.dat"));boolean fag=signature.verify(readerDat("mySignatrue.dat"));System.out.println(fag);}/** * 数字签名的，是通过不对称加密实现的。首先我们要创建一个钥匙包工厂或者说代理。创建一个钥匙包，在钥匙包里面取出唯一对应的 * 一对钥匙，一个是公用钥匙，一个是私有钥匙。Signature这个类就是签名类，通过开发文档我们理解了解到，签名的算法，我们要通过 * 与创建钥匙包的书法相互匹配。 * @throws Exception */@SuppressWarnings("unused")private static void mySignatureToByte() throws Exception {KeyPair keyPair=KeyPairGenerator.getInstance("RSA").generateKeyPair();PublicKey publicKey=keyPair.getPublic();PrivateKey privateKey=keyPair.getPrivate();byte[] src="田智文".getBytes();Signature signature=Signature.getInstance("MD5withRSA");signature.initSign(privateKey);signature.update(src);byte[] result=signature.sign();System.out.println(new String(result));writeDat(result, "mySignatrue.dat");writeDat(src, "src.dat");writeKey(publicKey, "mySignaturePublicKey.key");}/** * 根據用戶提供的密碼，來進行加密解密，雙方只是知道密碼。 * @param passWord 这个密码的长度只能是8的倍数这点需要注意 * @throws Exception */@SuppressWarnings("unused")private static void otherMySecretEncrypt(String passWord)throws Exception {Cipher cipher = Cipher.getInstance("PBEWithMD5AndDES");SecretKeyFactory factory = SecretKeyFactory.getInstance("PBEWithMD5AndDES");SecretKey key = factory.generateSecret(new PBEKeySpec(passWord.toCharArray()));// 这行代码，没有弄的太明白。具体的作用不是分了解。只是感觉这个对象会参与加密工作PBEParameterSpec parameterSpec = new PBEParameterSpec(new byte[] { 1,2, 3, 4, 5, 6, 7, 8 }, 1000);cipher.init(Cipher.ENCRYPT_MODE, key, parameterSpec);byte[] result = cipher.doFinal("根据个人密码加密的测试".getBytes());System.out.println(new String(result));writeDat(result, "otherMySecretEncrypt.dat");}@SuppressWarnings("unused")private static void otherMySecretDncrypt(String passWord)throws Exception{Cipher cipher=Cipher.getInstance("PBEWithMD5AndDES");SecretKey key=SecretKeyFactory.getInstance("PBEWithMD5AndDES").generateSecret(new PBEKeySpec(passWord.toCharArray()));// 这行代码，没有弄的太明白。具体的作用不是分了解。只是感觉这个对象会参与加密工作PBEParameterSpec parameterSpec = new PBEParameterSpec(new byte[] { 1,2, 3, 4, 5, 6, 7, 8 }, 1000);cipher.init(Cipher.DECRYPT_MODE, key, parameterSpec);byte[] result=cipher.doFinal(readerDat("otherMySecretEncrypt.dat"));System.out.println(new String(result));}@SuppressWarnings("unused")private static void mySecretPariEncrypt() throws Exception {Cipher cipher = Cipher.getInstance("RSA");KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA");KeyPair keyPair = generator.generateKeyPair();PublicKey publicKey = keyPair.getPublic();PrivateKey privateKey = keyPair.getPrivate();cipher.init(Cipher.ENCRYPT_MODE, publicKey);byte[] result = cipher.doFinal("测试，非对称密码绑定".getBytes());System.out.println(new String(result));writeDat(result, "SecretPair_Encrpt.dat");writeKey(privateKey, "SecretPairPrivate.key");}@SuppressWarnings("unused")private static void mySecretPairDncrypt() throws Exception {Cipher cipher = Cipher.getInstance("RSA");PrivateKey privateKey = (PrivateKey) readerKey("SecretPairPrivate.key");cipher.init(Cipher.DECRYPT_MODE, privateKey);byte[] result = cipher.doFinal(readerDat("SecretPair_Encrpt.dat"));System.out.println(new String(result));}@SuppressWarnings("unused")private static void myEncrpt() throws Exception {Cipher cipher = Cipher.getInstance("DES");Key secretKey = readerKey("tianzhw.key");cipher.init(Cipher.DECRYPT_MODE, secretKey);byte[] result = cipher.doFinal(readerDat("tianzhw.dat"));System.out.println(new String(result));}@SuppressWarnings("unused")private static void myDncrypt() throws Exception {Cipher cipher = Cipher.getInstance("DES");KeyGenerator generator = KeyGenerator.getInstance("DES");Key secretKey = generator.generateKey();cipher.init(Cipher.ENCRYPT_MODE, secretKey);byte[] result = cipher.doFinal("extra rich".getBytes("gbk"));System.out.println(new String(result));writeDat(result, "tianzhw.dat");writeKey(secretKey, "tianzhw.key");}@SuppressWarnings("unused")private static void writeDat(byte[] src, String fileName) throws Exception {FileOutputStream outputStream = new FileOutputStream(fileName);outputStream.write(src);outputStream.close();}private static void writeKey(Key key, String fileName) throws Exception {ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(fileName));oos.writeObject(key);oos.close();}@SuppressWarnings("unused")private static byte[] readerDat(String fileName) throws Exception {File file = new File(fileName);byte[] result = null;if (!file.exists()) {System.out.println("文件不存在");return null;} else {result = new byte[(int) file.length()];FileInputStream inputStream = new FileInputStream(file);int len = inputStream.read(result);int total = 0;while (total < result.length) {total += len;inputStream.read(result, total, (result.length - total));}inputStream.close();}return result;}private static Key readerKey(String fileName) throws Exception {ObjectInputStream stream = new ObjectInputStream(new FileInputStream(fileName));Object obj = stream.readObject();stream.close();return (Key) obj;}}