JWT 和 JJWT，别再傻傻分不清了！

jwt是什么?

JWTs是JSON对象的编码表示。JSON对象由零或多个名称/值对组成，其中名称为字符串，值为任意JSON值。

JWT有助于在clear(例如在URL中)发送这样的信息，可以被信任为不可读(即加密的)、不可修改的(即签名)和URL - safe(即Base64编码的)。

jwt的组成

• Header: 标题包含了令牌的元数据，并且在最小包含签名和/或加密算法的类型
• Claims: Claims包含您想要签署的任何信息
• JSON Web Signature (JWS): 在header中指定的使用该算法的数字签名和声明

例如：

Header:

{
  "alg": "HS256",
  "typ": "JWT"
}

Claims:

{
  "sub": "1234567890",
  "name": "John Doe",
  "admin": true
}

Signature:

base64UrlEncode(Header) + "." + base64UrlEncode(Claims),

加密生成的token：

如何保证 JWT 安全

有很多库可以帮助您创建和验证JWT，但是当使用JWT时，仍然可以做一些事情来限制您的安全风险。在您信任JWT中的任何信息之前，请始终验证签名。这应该是给定的。

换句话说，如果您正在传递一个秘密签名密钥到验证签名的方法，并且签名算法被设置为“none”，那么它应该失败验证。

确保签名的秘密签名，用于计算和验证签名。秘密签名密钥只能由发行者和消费者访问，不能在这两方之外访问。

不要在JWT中包含任何敏感数据。这些令牌通常是用来防止操作(未加密)的，因此索赔中的数据可以很容易地解码和读取。

如果您担心重播攻击，包括一个nonce(jti索赔)、过期时间(exp索赔)和创建时间(iat索赔)。这些在JWT规范中定义得很好。

jwt的框架：JJWT

JJWT是一个提供端到端的JWT创建和验证的Java库。永远免费和开源(Apache License，版本2.0)，JJWT很容易使用和理解。它被设计成一个以建筑为中心的流畅界面，隐藏了它的大部分复杂性。

• JJWT的目标是最容易使用和理解用于在JVM上创建和验证JSON Web令牌(JWTs)的库。
• JJWT是基于JWT、JWS、JWE、JWK和JWA RFC规范的Java实现。
• JJWT还添加了一些不属于规范的便利扩展，比如JWT压缩和索赔强制。

规范兼容:

• 创建和解析明文压缩JWTs
• 创建、解析和验证所有标准JWS算法的数字签名紧凑JWTs(又称JWSs):
• HS256: HMAC using SHA-256
• HS384: HMAC using SHA-384
• HS512: HMAC using SHA-512
• RS256: RSASSA-PKCS-v1_5 using SHA-256
• RS384: RSASSA-PKCS-v1_5 using SHA-384
• RS512: RSASSA-PKCS-v1_5 using SHA-512
• PS256: RSASSA-PSS using SHA-256 and MGF1 with SHA-256
• PS384: RSASSA-PSS using SHA-384 and MGF1 with SHA-384
• PS512: RSASSA-PSS using SHA-512 and MGF1 with SHA-512
• ES256: ECDSA using P-256 and SHA-256
• ES384: ECDSA using P-384 and SHA-384
• ES512: ECDSA using P-521 and SHA-512

这里以github上的demo演示，理解原理，集成到自己项目中即可。如果您正在学习Spring Boot，推荐一个连载多年还在继续更新的免费教程：http://blog.didispace.com/spring-boot-learning-2x/

应用采用 spring boot + angular + jwt

结构图

Maven 引进 : pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.nibado.example</groupId>
    <artifactId>jwt-angular-spring</artifactId>
    <version>0.0.2-SNAPSHOT</version>
    <properties>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>

        <commons.io.version>2.4</commons.io.version>
        <jjwt.version>0.6.0</jjwt.version>
        <junit.version>4.12</junit.version>
        <spring.boot.version>1.5.3.RELEASE</spring.boot.version>
    </properties>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>${spring.boot.version}</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>${spring.boot.version}</version>
        </dependency>
        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>${commons.io.version}</version>
        </dependency>
        <dependency>
            <groupId>io.jsonwebtoken</groupId>
            <artifactId>jjwt</artifactId>
            <version>${jjwt.version}</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>${junit.version}</version>
        </dependency>
    </dependencies>
</project>

WebApplication.java

package com.nibado.example.jwtangspr;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@EnableAutoConfiguration
@ComponentScan
@Configuration
public class WebApplication {
 
    //过滤器
    @Bean
    public FilterRegistrationBean jwtFilter() {
        final FilterRegistrationBean registrationBean = new FilterRegistrationBean();
        registrationBean.setFilter(new JwtFilter());
        registrationBean.addUrlPatterns("/api/*");
        return registrationBean;
    }

    public static void main(final String[] args) throws Exception {
        SpringApplication.run(WebApplication.class, args);
    }

}

JwtFilter.java

package com.nibado.example.jwtangspr;

import java.io.IOException;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;

import org.springframework.web.filter.GenericFilterBean;

import io.jsonwebtoken.Claims;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureException;

public class JwtFilter extends GenericFilterBean {

    @Override
    public void doFilter(final ServletRequest req,
                         final ServletResponse res,
                         final FilterChain chain) throws IOException, ServletException {
        final HttpServletRequest request = (HttpServletRequest) req;

        //客户端将token封装在请求头中，格式为（Bearer后加空格）：Authorization：Bearer +token
        final String authHeader = request.getHeader("Authorization");
        if (authHeader == null || !authHeader.startsWith("Bearer ")) {
            throw new ServletException("Missing or invalid Authorization header.");
        }

        //去除Bearer 后部分
        final String token = authHeader.substring(7);

        try {
         //解密token，拿到里面的对象claims
            final Claims claims = Jwts.parser().setSigningKey("secretkey")
                .parseClaimsJws(token).getBody();
            //将对象传递给下一个请求
            request.setAttribute("claims", claims);
        }
        catch (final SignatureException e) {
            throw new ServletException("Invalid token.");
        }

        chain.doFilter(req, res);
    }

}

UserController.java

package com.nibado.example.jwtangspr;

import java.util.Arrays;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.ServletException;

import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureAlgorithm;

@RestController
@RequestMapping("/user")
public class UserController {

 //这里模拟数据库
    private final Map<String, List<String>> userDb = new HashMap<>();

    @SuppressWarnings("unused")
    private static class UserLogin {
        public String name;
        public String password;
    }
    
    public UserController() {
        userDb.put("tom", Arrays.asList("user"));
        userDb.put("wen", Arrays.asList("user", "admin"));
    }
    /*以上是模拟数据库，并往数据库插入tom和sally两条记录*/
    
    
    @RequestMapping(value = "login", method = RequestMethod.POST)
    public LoginResponse login(@RequestBody final UserLogin login)
        throws ServletException {
        if (login.name == null || !userDb.containsKey(login.name)) {
            throw new ServletException("Invalid login");
        }
        
        //加密生成token
        return new LoginResponse(Jwts.builder().setSubject(login.name)
            .claim("roles", userDb.get(login.name)).setIssuedAt(new Date())
            .signWith(SignatureAlgorithm.HS256, "secretkey").compact());
    }

    @SuppressWarnings("unused")
    private static class LoginResponse {
        public String token;

        public LoginResponse(final String token) {
            this.token = token;
        }
    }
}

ApiController.java

package com.nibado.example.jwtangspr;

import io.jsonwebtoken.Claims;

import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;

import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/api")
public class ApiController {
 @SuppressWarnings("unchecked")
 @RequestMapping(value = "role/{role}", method = RequestMethod.GET)
 public Boolean login(@PathVariable final String role,
   final HttpServletRequest request) throws ServletException {
  final Claims claims = (Claims) request.getAttribute("claims");
  return ((List<String>) claims.get("roles")).contains(role);
 }
}

index.html

<!doctype html>
<html ng-app="myApp">
<head>
    <meta charset="utf-8"/>
    <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"/>
    <title>JSON Web Token / AngularJS / Spring Boot example</title>
    <meta name="description" content="">
    <meta name="viewport" content="width=device-width">
    <link rel="stylesheet" href="libs/bootstrap/css/bootstrap.css">
    <script src="libs/jquery/jquery.js"></script>
    <script src="libs/bootstrap/js/bootstrap.js"></script>
    <script src="libs/angular/angular.js"></script>
    <script src="app.js"></script>
</head>
<body>
<div class="container" ng-controller='MainCtrl'>
 <h1>{{greeting}}</h1>
 <div ng-show="!loggedIn()">
  Please log in (tom and sally are valid names)</br>
  <form ng-submit="login()">
   Username: <input type="text" ng-model="userName"/><span><input type="submit" value="Login"/>
  </form>
 </div>
 <div class="alert alert-danger" role="alert" ng-show="error.data.message">
   <span class="glyphicon glyphicon-exclamation-sign" aria-hidden="true"></span>
   <span class="sr-only">Error:</span>
   {{error.data.message}}
 </div> 
 <div ng-show="loggedIn()">
  <div class="row">
   <div class="col-md-6">
    <h3><span class="label label-success">Success!</span> Welcome {{userName}}</h3>
     <a href ng-click="logout()">(logout)</a>
   </div>
   <div class="col-md-4">
   <div class="row header">
   <div class="col-sm-4">{{userName}} is a</div>
  </div>
  <div class="row">
   <div class="col-sm-2">User</div>
   <div class="col-sm-2"><span class="glyphicon glyphicon-ok" aria-hidden="true" ng-show="roleUser"></span></div>
  </div>
  <div class="row">
   <div class="col-sm-2">Admin</div>
   <div class="col-sm-2"><span class="glyphicon glyphicon-ok" aria-hidden="true" ng-show="roleAdmin"></span></div>
  </div> 
  <div class="row">
   <div class="col-sm-2">Foo</div>
   <div class="col-sm-2"><span class="glyphicon glyphicon-ok" aria-hidden="true" ng-show="roleFoo"></span></div>
  </div>    
   </div>
  </div>
 </div>
</div>
</body>
</html>

​​app.js​​

var appModule = angular.module('myApp', []);

appModule.controller('MainCtrl', ['mainService','$scope','$http',
        function(mainService, $scope, $http) {
            $scope.greeting = 'Welcome to the JSON Web Token / AngularJR / Spring example!';
            $scope.token = null;
            $scope.error = null;
            $scope.roleUser = false;
            $scope.roleAdmin = false;
            $scope.roleFoo = false;

            $scope.login = function() {
                $scope.error = null;
                mainService.login($scope.userName).then(function(token) {
                    $scope.token = token;
                    $http.defaults.headers.common.Authorization = 'Bearer ' + token;
                    $scope.checkRoles();
                },
                function(error){
                    $scope.error = error
                    $scope.userName = '';
                });
            }

            $scope.checkRoles = function() {
                mainService.hasRole('user').then(function(user) {$scope.roleUser = user});
                mainService.hasRole('admin').then(function(admin) {$scope.roleAdmin = admin});
                mainService.hasRole('foo').then(function(foo) {$scope.roleFoo = foo});
            }

            $scope.logout = function() {
                $scope.userName = '';
                $scope.token = null;
                $http.defaults.headers.common.Authorization = '';
            }

            $scope.loggedIn = function() {
                return $scope.token !== null;
            }
        } ]);



appModule.service('mainService', function($http) {
    return {
        login : function(username) {
            return $http.post('/user/login', {name: username}).then(function(response) {
                return response.data.token;
            });
        },

        hasRole : function(role) {
            return $http.get('/api/role/' + role).then(function(response){
                console.log(response);
                return response.data;
            });
        }
    };
});

运行应用

效果