1. 什么是SSLSocket
JDK文档指出,SSLSocket扩展Socket并提供使用SSL或TLS协议的安全套接字。
这种套接字是正常的流套接字,但是它们在基础网络传输协议(如TCP)上添加了安全保护层。
具体安全方面的讨论见下一篇。本篇重点关注SSLSocket及相关几个类的使用。
2. SSLSocket和相关类
SSLSocket来自jsse(Java Secure Socket Extension)。
(1)SSLContext: 此类的实例表示安全套接字协议的实现, 它是SSLSocketFactory、SSLServerSocketFactory和SSLEngine的工厂。
(2)SSLSocket: 扩展自Socket
(3)SSLServerSocket: 扩展自ServerSocket
(4)SSLSocketFactory: 抽象类,扩展自SocketFactory, SSLSocket的工厂
(5)SSLServerSocketFactory: 抽象类,扩展自ServerSocketFactory, SSLServerSocket的工厂
(6)KeyStore: 表示密钥和证书的存储设施
(7)KeyManager: 接口,JSSE密钥管理器
(8)TrustManager: 接口,信任管理器(?翻译得很拗口)
(9)X590TrustedManager: TrustManager的子接口,管理X509证书,验证远程安全套接字
3. SSLContext的使用
[java] view plain copy print?
- public static void main(String[] args) throws Exception {
- X509TrustManager x509m = new X509TrustManager() {
- @Override
- public X509Certificate[] getAcceptedIssuers() {
- return null;
- }
- @Override
- public void checkServerTrusted(X509Certificate[] chain,
- String authType) throws CertificateException {
- }
- @Override
- public void checkClientTrusted(X509Certificate[] chain,
- String authType) throws CertificateException {
- }
- };
- // 获取一个SSLContext实例
- SSLContext s = SSLContext.getInstance("SSL");
- // 初始化SSLContext实例
- s.init(null, new TrustManager[] { x509m },
- new java.security.SecureRandom());
- // 打印这个SSLContext实例使用的协议
- System.out.println("缺省安全套接字使用的协议: " + s.getProtocol());
- // 获取SSLContext实例相关的SSLEngine
- SSLEngine e = s.createSSLEngine();
- System.out
- .println("支持的协议: " + Arrays.asList(e.getSupportedProtocols()));
- System.out.println("启用的协议: " + Arrays.asList(e.getEnabledProtocols()));
- System.out.println("支持的加密套件: "
- + Arrays.asList(e.getSupportedCipherSuites()));
- System.out.println("启用的加密套件: "
- + Arrays.asList(e.getEnabledCipherSuites()));
- }
运行结果如下:
SSLContext.getProtocol(): 返回当前SSLContext对象的协议名称
SSLContext.init(): 初始化当前SSLContext对象。 三个参数均可以为null。 详见JDK文档。
SSLEngine.getSupportedProtocols()等几个方法可以返回些 Engine上支持/已启用的协议、支持/已启用的加密套件
4. SSLSocket和SSLServerSocket的使用
这两个类的用法跟Socket/ServerSocket的用法比较类似。看下面的例子(主要为了验证SSLSocket的用法 ,I/O和多线程处理比较随意)
4.1 SSLServerSocket
(1)新建一个SSLServerSocket,并开始监听来自客户端的连接
[java] view plain copy print?
- // 抛出异常
- // javax.net.ssl.SSLException: No available certificate or key corresponds
- // to the SSL cipher suites which are enabled.
- public static void notOk() throws IOException {
- SSLServerSocketFactory factory = (SSLServerSocketFactory) SSLServerSocketFactory
- .getDefault();
- SSLServerSocket server = (SSLServerSocket) factory
- .createServerSocket(10000);
- System.out.println("ok");
- server.accept();
- }
server.accept()处抛出异常, 提示缺少证书。与ServerSocket不同, SSLServerSocket需要证书来进行安全验证。
使用keytool工具生成一个证书。 步骤如下, 得到一个名为cmkey的证书文件
(2)重新完善上面的代码。 主要增加两个功能: 使用名为cmkey的证书初始化SSLContext,
echo客户端的消息。 代码如下
[java] view plain copy print?
- // 启动一个ssl server socket
- // 配置了证书, 所以不会抛出异常
- public static void sslSocketServer() throws Exception {
- // key store相关信息
- String keyName = "cmkey";
- char[] keyStorePwd = "123456".toCharArray();
- char[] keyPwd = "123456".toCharArray();
- KeyStore keyStore = KeyStore.getInstance(KeyStore.getDefaultType());
- // 装载当前目录下的key store. 可用jdk中的keytool工具生成keystore
- InputStream in = null;
- keyStore.load(in = Test2.class.getClassLoader().getResourceAsStream(
- keyName), keyPwd);
- in.close();
- // 初始化key manager factory
- KeyManagerFactory kmf = KeyManagerFactory.getInstance(KeyManagerFactory
- .getDefaultAlgorithm());
- kmf.init(keyStore, keyPwd);
- // 初始化ssl context
- SSLContext context = SSLContext.getInstance("SSL");
- context.init(kmf.getKeyManagers(),
- new TrustManager[] { new MyX509TrustManager() },
- new SecureRandom());
- // 监听和接收客户端连接
- SSLServerSocketFactory factory = context.getServerSocketFactory();
- SSLServerSocket server = (SSLServerSocket) factory
- .createServerSocket(10002);
- System.out.println("ok");
- Socket client = server.accept();
- System.out.println(client.getRemoteSocketAddress());
- // 向客户端发送接收到的字节序列
- OutputStream output = client.getOutputStream();
- // 当一个普通 socket 连接上来, 这里会抛出异常
- // Exception in thread "main" javax.net.ssl.SSLException: Unrecognized
- // SSL message, plaintext connection?
- InputStream input = client.getInputStream();
- byte[] buf = new byte[1024];
- int len = input.read(buf);
- System.out.println("received: " + new String(buf, 0, len));
- output.write(buf, 0, len);
- output.flush();
- output.close();
- input.close();
- // 关闭socket连接
- client.close();
- server.close();
- }
4.2 SSLSocket
(1)我们先使用一个普通的Socket尝试连接服务器端
[java] view plain copy print?
- // 通过socket连接服务器
- public static void socket() throws UnknownHostException, IOException {
- Socket s = new Socket("localhost", 10002);
- System.out.println(s);
- System.out.println("ok");
- OutputStream output = s.getOutputStream();
- InputStream input = s.getInputStream();
- output.write("alert".getBytes());
- System.out.println("sent: alert");
- output.flush();
- byte[] buf = new byte[1024];
- int len = input.read(buf);
- System.out.println("received:" + new String(buf, 0, len));
- }
结果客户端和服务器端都出错。 客户端的错误是接收到乱码。
服务器则抛出异常
javax.net.ssl.SSLException: Unrecognized SSL message, plaintext connection?
(2)改成SSLSocket, 但是不使用证书。客户端抛出
sun.security.provider.certpath.SunCertPathBuilderException: unable to
find valid certification path to requested target
[java] view plain copy print?
- // 不使用证书, 通过ssl socket连接服务器
- // 抛出异常, 提示找不到证书
- public static void sslSocket() throws UnknownHostException, IOException {
- SSLSocketFactory factory = (SSLSocketFactory) SSLSocketFactory
- .getDefault();
- SSLSocket s = (SSLSocket) factory.createSocket("localhost", 10002);
- System.out.println("ok");
- OutputStream output = s.getOutputStream();
- InputStream input = s.getInputStream();
- output.write("alert".getBytes());
- System.out.println("sent: alert");
- output.flush();
- byte[] buf = new byte[1024];
- int len = input.read(buf);
- System.out.println("received:" + new String(buf, 0, len));
- }
程序客户在不持有证书的情况下直接进行连接,服务器端会产生运行时异常javax.net.ssl.SSLHandshakeException: Received fatal alert: certificate_unknown,不允许进行连接。 我们可以指定像下面这样执行客户端,服务器端可以成功echo客户端的发出的字符串"alert"
java -Djavax.net.ssl.trustStore=cmkey Client
这里的cmkey即前面生成的证书文件。
(3)改成SSLSocket, 对SSLContext进行如下初始化。
[java] view plain copy print?
- public static void sslSocket2() throws Exception {
- SSLContext context = SSLContext.getInstance("SSL");
- // 初始化
- context.init(null,
- new TrustManager[] { new Test2.MyX509TrustManager() },
- new SecureRandom());
- SSLSocketFactory factory = context.getSocketFactory();
- SSLSocket s = (SSLSocket) factory.createSocket("localhost", 10002);
- System.out.println("ok");
- OutputStream output = s.getOutputStream();
- InputStream input = s.getInputStream();
- output.write("alert".getBytes());
- System.out.println("sent: alert");
- output.flush();
- byte[] buf = new byte[1024];
- int len = input.read(buf);
- System.out.println("received:" + new String(buf, 0, len));
- }
转载出处:http://410063005.iteye.com/blog/1751243点击打开链接