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576 lines
19 KiB
576 lines
19 KiB
3 years ago
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#Java安全
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##为什么要掌握Java安全？
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* 提升逼格，现在市场上的大部分程序员都对Java安全、数据加密等等一无所知，而现在的面试中很多面试官为了凸显自己的高逼格，总爱问你一些安全相关的问题。只有掌握了Java安全相关知识，才能跟面试官站在同一逼格线，进行愉快滴交流。
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* 项目中到处需要。如：账号密码的加密，订单支付的加密，个人资料的加密等等。
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* 初级工程师向中高级工程师进阶的必经之路。
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##什么是加密？
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* 古老的加密方法：《潜伏》中的余则成，收到密码：12 25 13 15 29 19；《模仿游戏》，二战时期，德国的密码机及图灵为了破解德军密码而研制出第一代计算机（图灵机）。
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* 对称加密和非对称加密等等。
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* MD5，属于消息摘要（Message Digest）。
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## 学习目标
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1. 复习字节与字符、字符编码、进制转换、java里的io
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2. 一些基本的安全知识
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3. 三大风险：窃听风险、篡改风险、冒充风险
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4. 重放攻击（wpe）
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5. 常用加密算法（对称/非对称）
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6. 消息摘要
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7. 数字签名
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8. 数字证书
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9. Keytool工具的使用
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10. SSL/TLS的工作原理
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11. Https双向认证原理
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#凯撒密码
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##第一个案例，对字符进行简单的加密。
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* 对字符数组中所有的字符做+1处理（后面可以转换成+num这个数由通讯双方来协定）
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###代码
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/**
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* @author Camille
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*对字符简单的加密
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*/
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public class SimpleEncryptionDemo01 {
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public static void main(String[] args) {
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// 确定加密的内容
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String content = "i love you tonight 404 see you z";
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//加密
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String encryptData = encrypt(content);
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System.out.println("加密后：" + encryptData);
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//解密
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String decryptData = decrypt(encryptData);
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System.out.println("解密后：" + decryptData);
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}
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/**
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* 加密方法
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*
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* @param content
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* @return
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*/
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public static String encrypt(String content) {
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// 将内容转换成字符数组
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char[] charArray = content.toCharArray();
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// 遍历出所有字符
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for (int i = 0; i < charArray.length; i++) {
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// 对所有字符进行 + 1操作
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charArray[i] = (char) (charArray[i] + 1);
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}
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return new String(charArray);
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}
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/**
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* 解密方法
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*
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* @param encryptData
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* @return
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*/
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public static String decrypt(String encryptData) {
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// 将内容转换成字符数组
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char[] charArray = encryptData.toCharArray();
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System.out.println(new String(charArray));
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// 解密
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for (int i = 0; i < charArray.length; i++) {
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charArray[i] = (char) (charArray[i] - 1);
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}
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return new String(charArray);
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}
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}
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##第二个案例，对字节进行简单的加密。
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**字节和字符的区别？**
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* UTF-8编码下，一个英文或数字字符就是一个字节
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* UTF-8编码下，一个汉字代表三个字节。
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* 为什么new String(bytes)的时候回发生乱码，就是因为加密后得到的字节找不到对应的字符。
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* Base64的原理
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###代码
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/**
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* @author Camille
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*对字节进行加密
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*/
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public class SimpleEncryptionDemo2 {
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public static void main(String[] args) {
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// 测试字节字符
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String content = "中文";
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int key = 80;
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String encryptData = encrypt(content,key);
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System.out.println("＋密后:" + encryptData);
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String decryptData = decrypt(encryptData,key);
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System.out.println("解密后:" + decryptData);
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}
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/**
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* 加密
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*
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* @param content
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* @return
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*/
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public static String encrypt(String content,int key) {
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// 第一步，转换成字节数组
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byte[] bytes = content.getBytes();
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System.out.println("打印未加密的字节数组：");
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Util.printBytes(bytes);
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System.out.println("_________________________________________");
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// 第二步，遍历出所有字节，并做+1处理
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for (int i = 0; i < bytes.length; i++) {
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bytes[i] = (byte) (bytes[i] + key);
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}
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System.out.println("打印加密的字节数组：");
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Util.printBytes(bytes);
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System.out.println("_________________________________________");
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// return new String(bytes);
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return Base64.getEncoder().encodeToString(bytes);
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}
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/**
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* 解密
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* @param encryptData
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* @return
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*/
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public static String decrypt(String encryptData,int key) {
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// 第一步，转换成字节数组,加密时使用Base64编码，那解密时也要使用Base64解码
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byte[] bytes = Base64.getDecoder().decode(encryptData);
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// byte[] bytes = encryptData.getBytes();
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System.out.println("打印经过两次转换后的字节数组：");
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Util.printBytes(bytes);
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System.out.println("_________________________________________");
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// 解密
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for (int i = 0; i < bytes.length; i++) {
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bytes[i] = (byte) (bytes[i] - key);
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}
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System.out.println("打印解密后的字节数组：");
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Util.printBytes(bytes);
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System.out.println("_________________________________________");
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return new String(bytes);
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}
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}
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##对称加密与非对称加密
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* 对称加密与非对称加密的区别
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* 对称加密。同一把钥匙进行加密和解密
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* 非对称加密，公钥加密，私钥解密。
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##对称加密的案例
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常见算法：AES、DES、3DES、TDEA、Blowfish、RC2、RC4、RC5、IDEA、SKIPJACK
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AES:高级加密标准（Advanced Encryption Standard)
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DES:数据加密标准(Data Encryption Standard)
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###对称加密第一个案例，代码，。
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public class SymmetricalEncryptionDemo01 {
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public static void main(String[] args) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException,
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IllegalBlockSizeException, BadPaddingException {
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// 声明要加密的内容
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String content = "今晚404，不见不散";
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//生成key
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SecretKey key = createKey();
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//加密
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String encryptData = encrypt(content, key);
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System.out.println(encryptData);
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//解密
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String decryptData = decrypt(encryptData, key);
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System.out.println(decryptData);
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}
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/**
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* 生成key
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* @return
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* @throws NoSuchAlgorithmException
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*/
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public static SecretKey createKey() throws NoSuchAlgorithmException {
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// 生成key
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KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
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SecretKey secretKey = keyGenerator.generateKey();
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return secretKey;
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}
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/**
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* 加密方法
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*
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* @param content
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* @return
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* @throws InvalidKeyException
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* @throws NoSuchPaddingException
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* @throws NoSuchAlgorithmException
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* @throws BadPaddingException
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* @throws IllegalBlockSizeException
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*/
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public static String encrypt(String content, SecretKey key) throws InvalidKeyException, NoSuchAlgorithmException,
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NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException {
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// 获取cipher单例对象
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Cipher cipher = Cipher.getInstance("AES");
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// 初始化cipher,设置为加密模式
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cipher.init(Cipher.ENCRYPT_MODE, key);
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// 开始加密
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byte[] encryptBytes = cipher.doFinal(content.getBytes());
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return Base64.getEncoder().encodeToString(encryptBytes);
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}
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/**
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* @param encryptData
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* @return
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*/
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public static String decrypt(String encryptData, SecretKey key) throws InvalidKeyException,
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NoSuchAlgorithmException, NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException {
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byte[] encryptBytes = Base64.getDecoder().decode(encryptData);
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// 获取cipher单例对象
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Cipher cipher = Cipher.getInstance("AES");
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// 解密
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cipher.init(Cipher.DECRYPT_MODE, key);
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byte[] decryptBytes = cipher.doFinal(encryptBytes);
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return new String(decryptBytes);
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}
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}
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###对称加密的第二个案例，将生成的key保存到本地，然后解密时和下一次加密时就只需要到本地读取即可。。
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/**
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* @author Camille
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*保存key到本地
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*/
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public class SymmetricalEncryptionDemo02 {
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public static void main(String[] args) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException,
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IllegalBlockSizeException, BadPaddingException, IOException, ClassNotFoundException {
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// 声明要加密的内容
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String content = "今晚404，不见不散";
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//第一次生成key,并序列化到本地
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// SecretKey key = createKey();
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// SerializableUtil.saveObject2File("heima.key", key);
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//从文件中读取key
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SecretKey key = (SecretKey) SerializableUtil.readObjectFromFile("heima.key");
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System.out.println(key);
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//加密
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String encryptData = encrypt(content, key);
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System.out.println(encryptData);
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//解密
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String decryptData = decrypt(encryptData, key);
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System.out.println(decryptData);
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}
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/**
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* 生成key
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* @return
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* @throws NoSuchAlgorithmException
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*/
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public static SecretKey createKey() throws NoSuchAlgorithmException {
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// 生成key
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KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
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SecretKey secretKey = keyGenerator.generateKey();
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return secretKey;
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}
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/**
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* 加密方法
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*
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* @param content
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* @return
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* @throws InvalidKeyException
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* @throws NoSuchPaddingException
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* @throws NoSuchAlgorithmException
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* @throws BadPaddingException
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* @throws IllegalBlockSizeException
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*/
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public static String encrypt(String content, SecretKey key) throws InvalidKeyException, NoSuchAlgorithmException,
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NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException {
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// 获取cipher单例对象
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Cipher cipher = Cipher.getInstance("AES");
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// 初始化cipher,设置为加密模式
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cipher.init(Cipher.ENCRYPT_MODE, key);
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// 开始加密
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byte[] encryptBytes = cipher.doFinal(content.getBytes());
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return Base64.getEncoder().encodeToString(encryptBytes);
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}
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/**
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* @param encryptData
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* @return
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*/
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public static String decrypt(String encryptData, SecretKey key) throws InvalidKeyException,
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NoSuchAlgorithmException, NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException {
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byte[] encryptBytes = Base64.getDecoder().decode(encryptData);
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// 获取cipher单例对象
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Cipher cipher = Cipher.getInstance("AES");
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// 解密
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cipher.init(Cipher.DECRYPT_MODE, key);
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byte[] decryptBytes = cipher.doFinal(encryptBytes);
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return new String(decryptBytes);
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}
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}
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**保存对象到文件**
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/**
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* 保存对象到本地
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*
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* @param obj
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* @throws IOException
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*/
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public static void saveObject2File(String fileName, Object obj) throws IOException {
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FileOutputStream fos = new FileOutputStream(new File(fileName));
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ObjectOutputStream oos = new ObjectOutputStream(fos);
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oos.writeObject(obj);
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}
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**从文件中读取对象**
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/**
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* 从文件中读取对象
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* @param fileName
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* @return
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* @throws IOException
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* @throws ClassNotFoundException
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*/
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public static Object readObjectFromFile(String fileName) throws IOException, ClassNotFoundException {
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FileInputStream fis = new FileInputStream(new File(fileName));
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ObjectInputStream ois = new ObjectInputStream(fis);
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Object object = ois.readObject();
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return object;
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}
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###第三个案例——自定义秘钥，代码
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/**
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* 生成key
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* @return
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* @throws NoSuchAlgorithmException
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*/
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public static SecretKey createKey(String keyword) throws NoSuchAlgorithmException {
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// 生成key
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KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
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keyGenerator.init(new SecureRandom(keyword.getBytes()));
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SecretKey secretKey = keyGenerator.generateKey();
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return secretKey;
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}
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###应用场景
|
||
|
|
* 登录，post请求{username=lisi,pw=加密}
|
||
|
|
|
||
|
|
##非对称加密的案例
|
||
|
|
常见算法：RSA、Elgamal、背包算法、Rabin、D-H、ECC（椭圆曲线加密算法）等
|
||
|
|
应用场景：银行和电商网站，他就采用非对称加密，将公钥给所有人，你们就用这个公钥加密，私钥我自己留着，谁也不知道，所以除了我，谁也解密不了。
|
||
|
|
###第一个案例（数据量不大的情况下可用，加密数据小于117个字节，解密数据小于128个字节）
|
||
|
|
public class AysmmetricEncryptionDemo {
|
||
|
|
|
||
|
|
public static void main(String[] args) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException,
|
||
|
|
IllegalBlockSizeException, BadPaddingException {
|
||
|
|
String content = "今晚小树林，等你哦";
|
||
|
|
//生成密钥对
|
||
|
|
KeyPair keyPair = createKeyypair();
|
||
|
|
//获取公钥私钥
|
||
|
|
PublicKey publicKey = keyPair.getPublic();
|
||
|
|
PrivateKey privateKey = keyPair.getPrivate();
|
||
|
|
//加密
|
||
|
|
String encryptData = encrypt(content, publicKey);
|
||
|
|
System.out.println("加密后：" + encryptData);
|
||
|
|
//解密
|
||
|
|
String decryptData = decrypt(encryptData, privateKey);
|
||
|
|
System.out.println("解密后：" + decryptData);
|
||
|
|
}
|
||
|
|
/**
|
||
|
|
* 生成秘钥对
|
||
|
|
* @return
|
||
|
|
* @throws NoSuchAlgorithmException
|
||
|
|
*/
|
||
|
|
public static KeyPair createKeyypair() throws NoSuchAlgorithmException{
|
||
|
|
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
|
||
|
|
KeyPair keyPair = keyPairGenerator.generateKeyPair();
|
||
|
|
return keyPair;
|
||
|
|
}
|
||
|
|
/**
|
||
|
|
* 加密
|
||
|
|
*
|
||
|
|
* @param content
|
||
|
|
* @return
|
||
|
|
* @throws NoSuchPaddingException
|
||
|
|
* @throws NoSuchAlgorithmException
|
||
|
|
* @throws BadPaddingException
|
||
|
|
* @throws IllegalBlockSizeException
|
||
|
|
* @throws InvalidKeyException
|
||
|
|
*/
|
||
|
|
public static String encrypt(String content, PublicKey publicKey) throws NoSuchAlgorithmException,
|
||
|
|
NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException, InvalidKeyException {
|
||
|
|
// 获取cipher对象
|
||
|
|
Cipher cipher = Cipher.getInstance("RSA");
|
||
|
|
// 初始化cipher，指定模式为加密，传入公钥
|
||
|
|
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
|
||
|
|
byte[] encryptBytes = cipher.doFinal(content.getBytes());
|
||
|
|
return Base64.getEncoder().encodeToString(encryptBytes);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* 解密方法
|
||
|
|
*
|
||
|
|
* @param encryptData
|
||
|
|
* @param privateKey
|
||
|
|
* @return
|
||
|
|
* @throws NoSuchPaddingException
|
||
|
|
* @throws NoSuchAlgorithmException
|
||
|
|
* @throws InvalidKeyException
|
||
|
|
* @throws BadPaddingException
|
||
|
|
* @throws IllegalBlockSizeException
|
||
|
|
* @throws Exception
|
||
|
|
*/
|
||
|
|
public static String decrypt(String encryptData, PrivateKey privateKey) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException{
|
||
|
|
byte[] encryptBytes = Base64.getDecoder().decode(encryptData);
|
||
|
|
// 获取cipher对象
|
||
|
|
Cipher cipher = Cipher.getInstance("RSA");
|
||
|
|
// 小芝解密
|
||
|
|
cipher.init(Cipher.DECRYPT_MODE, privateKey);
|
||
|
|
byte[] decryptBytes = cipher.doFinal(encryptBytes);
|
||
|
|
return new String(decryptBytes);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
###如果数据量大的话，则要对要加密、解密的数据进行分块处理，代码如下：
|
||
|
|
|
||
|
|
/**
|
||
|
|
* 处理大量数据时，分块加密/解密
|
||
|
|
* @param content
|
||
|
|
* @param cipher
|
||
|
|
* @param max
|
||
|
|
* @return
|
||
|
|
* @throws IllegalBlockSizeException
|
||
|
|
* @throws BadPaddingException
|
||
|
|
* @throws IOException
|
||
|
|
*/
|
||
|
|
private static byte[] doFinalWithBlock(byte[] bytes, Cipher cipher,int max)
|
||
|
|
throws IllegalBlockSizeException, BadPaddingException, IOException {
|
||
|
|
int len = bytes.length;//3000
|
||
|
|
//加密数据长度不能超过117个byte
|
||
|
|
int inputOffset = 0;//2700
|
||
|
|
ByteArrayOutputStream baos = new ByteArrayOutputStream();
|
||
|
|
while (len > inputOffset) {
|
||
|
|
//特殊情况，最后一次剩下的数据不足117
|
||
|
|
if ((len - inputOffset) >= max) {
|
||
|
|
byte[] encryptBytes = cipher.doFinal(bytes, inputOffset, max);
|
||
|
|
baos.write(encryptBytes);
|
||
|
|
inputOffset += max;
|
||
|
|
}else {
|
||
|
|
byte[] encryptBytes = cipher.doFinal(bytes, inputOffset, len - inputOffset);
|
||
|
|
baos.write(encryptBytes);
|
||
|
|
inputOffset = len;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
byte[] byteArray = baos.toByteArray();
|
||
|
|
return byteArray;
|
||
|
|
}
|
||
|
|
|
||
|
|
##消息摘要
|
||
|
|
消息摘要是一个不可逆的过程。常用来防篡改。
|
||
|
|
|
||
|
|
常见算法：MD5、SHA、CRC等
|
||
|
|
|
||
|
|
###byte数组和16进制字符串的互转
|
||
|
|
|
||
|
|
/**
|
||
|
|
* byte数组转16进制字符串
|
||
|
|
* @param bytes
|
||
|
|
* @return
|
||
|
|
*/
|
||
|
|
public static String bytes2Hex(byte[] bytes){
|
||
|
|
StringBuffer sBuffer = new StringBuffer();
|
||
|
|
for (int i = 0; i < bytes.length; i++) {
|
||
|
|
//取高位
|
||
|
|
int high = (bytes[i] & 0xf0) >> 4;
|
||
|
|
//取低位
|
||
|
|
int low = bytes[i] & 0x0f;
|
||
|
|
sBuffer.append(HEXSTR[high]).append(HEXSTR[low]);
|
||
|
|
}
|
||
|
|
return sBuffer.toString();
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* 16进制字符串转字节数组
|
||
|
|
* @param hex
|
||
|
|
* @return
|
||
|
|
*/
|
||
|
|
public static byte[] hex2Bytes(String hex){
|
||
|
|
int len = hex.length()/2;
|
||
|
|
//声明一个字节数组用于接收转换后的字节
|
||
|
|
byte[] bytes = new byte[len];
|
||
|
|
for (int i = 0; i < len; i++) {
|
||
|
|
//首先取高位,取偶数位
|
||
|
|
String highStr = hex.substring(2 * i, 2 * i + 1);
|
||
|
|
String lowStr = hex.substring(2 * i + 1, 2 * i + 2);
|
||
|
|
int high = Integer.parseInt(highStr, 16) << 4;
|
||
|
|
int low = Integer.parseInt(lowStr, 16);
|
||
|
|
bytes[i] = (byte) (high + low);
|
||
|
|
}
|
||
|
|
return bytes;
|
||
|
|
}
|
||
|
|
|
||
|
|
##数字签名
|
||
|
|
|
||
|
|
**签名过程**
|
||
|
|
|
||
|
|
String content = "404房卡";
|
||
|
|
Signature signature = Signature.getInstance("MD5withRSA");
|
||
|
|
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
|
||
|
|
KeyPair keyPair = keyPairGenerator.generateKeyPair();
|
||
|
|
PrivateKey privateKey = keyPair.getPrivate();
|
||
|
|
PublicKey publicKey = keyPair.getPublic();
|
||
|
|
signature.initSign(privateKey);
|
||
|
|
signature.update(content.getBytes());
|
||
|
|
byte[] sign = signature.sign();
|
||
|
|
|
||
|
|
###数字签名的流程(画图理解)
|
||
|
|
###Signature**
|
||
|
|
|
||
|
|
//小芝认证
|
||
|
|
signature.initVerify(publicKey);
|
||
|
|
//我们要对房卡进行认证
|
||
|
|
// String content2 = "505的房卡";
|
||
|
|
signature.update(content.getBytes());
|
||
|
|
boolean verify = signature.verify(sign);
|
||
|
|
Util.printBytes(sign);
|
||
|
|
System.out.println(verify);
|
||
|
|
##keytool的使用。
|
||
|
|
* 生成keyPair keytool -genkeypair
|
||
|
|
* 修改别名 keytool -changealias -alias mykey -destalias heima1
|
||
|
|
* 导出证书 keytool -exportcert
|
||
|
|
* 导入证书 keytool -importcert
|
||
|
|
|
||
|
|
**获取文件中的证书**
|
||
|
|
|
||
|
|
// 获取证书工厂的实例
|
||
|
|
CertificateFactory cf = CertificateFactory.getInstance("X.509");
|
||
|
|
FileInputStream inStream = new FileInputStream(new File("heima.cer"));
|
||
|
|
X509Certificate certificate = (X509Certificate) cf.generateCertificate(inStream);
|
||
|
|
|
||
|
|
##SSl
|
||
|
|
**双向认证的原理**
|
||
|
|
**代码访问12306**
|
||
|
|
|
||
|
|
public class HttpsDemo {
|
||
|
|
|
||
|
|
public static void main(String[] args) throws IOException, NoSuchAlgorithmException, KeyManagementException, KeyStoreException, CertificateException {
|
||
|
|
//第一种方式，我所有的证书都不检查
|
||
|
|
SSLContext sslContext = SSLContext.getInstance("TLS");//TLS 是transport Layer safe
|
||
|
|
//获取信任管理者工厂
|
||
|
|
TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
|
||
|
|
//获取keyStore
|
||
|
|
KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType());
|
||
|
|
ks.load(null);
|
||
|
|
//从文件中读取证书
|
||
|
|
CertificateFactory cf = CertificateFactory.getInstance("X.509");
|
||
|
|
FileInputStream inStream = new FileInputStream(new File("srca.cer"));
|
||
|
|
X509Certificate cert = (X509Certificate) cf.generateCertificate(inStream);
|
||
|
|
//给keyStore设置证书
|
||
|
|
ks.setCertificateEntry("12306", cert);
|
||
|
|
trustManagerFactory.init(ks);
|
||
|
|
TrustManager[] tm = trustManagerFactory.getTrustManagers();
|
||
|
|
sslContext.init(null, tm, null);
|
||
|
|
SSLSocketFactory socketFactory = sslContext.getSocketFactory();
|
||
|
|
HttpsURLConnection.setDefaultSSLSocketFactory(socketFactory);
|
||
|
|
// TODO Auto-generated method stub
|
||
|
|
URL url = new URL("https://kyfw.12306.cn/otn/");
|
||
|
|
//第二步，获取coon
|
||
|
|
HttpsURLConnection coon = (HttpsURLConnection) url.openConnection();
|
||
|
|
InputStream inputStream = coon.getInputStream();
|
||
|
|
String response = Util.inputStream2String(inputStream);
|
||
|
|
System.out.println(response);
|
||
|
|
}
|
||
|
|
}
|