Java通信协议------SSL

朱雀 2023-10-10 10:49 102阅读 0赞

### [SSL介绍与Java实例][SSL_Java] ###

有关SSL的原理和介绍在网上已经有不少，对于Java下使用keytool生成证书，配置SSL通信的教程也非常多。但如果我们不能够亲自动手做一个SSL Sever和SSL Client，可能就永远也不能深入地理解Java环境下，SSL的通信是如何实现的。对SSL中的各种概念的认识也可能会仅限于可以使用的程度。本文通过构造一个简单的SSL Server和SSL Client来讲解Java环境下SSL的通信原理。

首先我们先回顾一下常规的Java Socket编程。在Java下写一个Socket服务器和客户端的例子还是比较简单的。以下是服务端的代码：

Java代码  
1.package org.bluedash.tryssl;  
2.  
3.import java.io.BufferedReader;  
4.import java.io.IOException;  
5.import java.io.InputS[tb][]reamReader;  
6.import java.io.PrintWriter;  
7.import java.net.ServerSocket;  
8.import java.net.Socket;  
9.  
10.public class Server extends Thread \{  
11. private Socket socket;  
12.  
13. public Server(Socket socket) \{  
14. this.socket = socket;  
15. \}  
16.  
17. public void run() \{  
18. try \{  
19. BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));  
20. PrintWriter writer = new PrintWriter(socket.getOutputStream());  
21.  
22. String data = reader.readLine();  
23. writer.println(data);  
24. writer.close();  
25. socket.close();  
26. \} catch (IOException e) \{  
27.  
28. \}  
29. \}  
30.  
31. public static void main(String\[\] args) throws Exception \{  
32. while (true) \{  
33. new Server((new ServerSocket(8080)).accept()).start();  
34. \}  
35. \}  
36.\}  
package org.bluedash.tryssl;

import java.io.BufferedReader;  
import java.io.IOException;  
import java.io.InputStreamReader;  
import java.io.PrintWriter;  
import java.net.ServerSocket;  
import java.net.Socket;

public class Server extends Thread \{  
private Socket socket;

public Server(Socket socket) \{  
this.socket = socket;  
\}

public void run() \{  
try \{  
BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));  
PrintWriter writer = new PrintWriter(socket.getOutputStream());

String data = reader.readLine();  
writer.println(data);  
writer.close();  
socket.close();  
\} catch (IOException e) \{

\}  
\}  
  
public static void main(String\[\] args) throws Exception \{  
while (true) \{  
new Server((new ServerSocket(8080)).accept()).start();  
\}  
\}  
\}

服务端很简单：侦听8080端口，并把客户端发来的字符串返回去。下面是客户端的代码：

Java代码  
1.package org.bluedash.tryssl;  
2.  
3.import java.io.BufferedReader;  
4.import java.io.InputStreamReader;  
5.import java.io.PrintWriter;  
6.import java.net.Socket;  
7.  
8.public class Client \{  
9.  
10. public static void main(String\[\] args) throws Exception \{  
11.  
12. Socket s = new Socket("localhost", 8080);  
13.  
14. PrintWriter writer = new PrintWriter(s.getOutputStream());  
15. BufferedReader reader = new BufferedReader(new InputStreamReader(s.getInputStream()));  
16. writer.println("hello");  
17. writer.flush();  
18. System.out.println(reader.readLine());  
19. s.close();  
20. \}  
21.  
22.\}  
package org.bluedash.tryssl;

import java.io.BufferedReader;  
import java.io.InputStreamReader;  
import java.io.PrintWriter;  
import java.net.Socket;

public class Client \{

public static void main(String\[\] args) throws Exception \{

Socket s = new Socket("localhost", 8080);

PrintWriter writer = new PrintWriter(s.getOutputStream());  
BufferedReader reader = new BufferedReader(new InputStreamReader(s.getInputStream()));  
writer.println("hello");  
writer.flush();  
System.out.println(reader.readLine());  
s.close();  
\}

客户端也非常简单：向服务端发起请求，发送一个"hello"字串，然后获得服务端的返回。把服务端运行起来后，执行客户端，我们将得到"hello"的返回。

就是这样一套简单的网络通信的代码，我们来把它改造成使用SSL通信。在SSL通信协议中，我们都知道首先服务端必须有一个数字证书，当客户端连接到服务端时，会得到这个证书，然后客户端会判断这个证书是否是可信的，如果是，则交换信道加密密钥，进行通信。如果不信任这个证书，则连接失败。

因此，我们首先要为服务端生成一个数字证书。Java环境下，数字证书是用keytool生成的，这些证书被存储在store的概念中，就是证书仓库。我们来调用keytool命令为服务端生成数字证书和保存它使用的证书仓库：

Bash代码  
1.keytool -genkey -v -alias bluedash-ssl-demo-server -keyalg RSA -keystore ./server\_ks -dname "CN=localhost,OU=cn,O=cn,L=cn,ST=cn,C=cn" -storepass server -keypass 123123  
keytool -genkey -v -alias bluedash-ssl-demo-server -keyalg RSA -keystore ./server\_ks -dname "CN=localhost,OU=cn,O=cn,L=cn,ST=cn,C=cn" -storepass server -keypass 123123

这样，我们就将服务端证书bluedash-ssl-demo-server保存在了server\_ksy这个store文件当中。有关keytool的用法在本文中就不再多赘述。执行上面的命令得到如下结果：

Bash代码  
1.Generating 1,024 bit RSA key pair and self-signed certificate (SHA1withRSA) with a validity of 90 days  
2. for: CN=localhost, OU=cn, O=cn, L=cn, ST=cn, C=cn  
3.\[Storing ./server\_ks\]  
Generating 1,024 bit RSA key pair and self-signed certificate (SHA1withRSA) with a validity of 90 days  
for: CN=localhost, OU=cn, O=cn, L=cn, ST=cn, C=cn  
\[Storing ./server\_ks\]

然后，改造我们的服务端代码，让服务端使用这个证书，并提供SSL通信：

Java代码  
1.package org.bluedash.tryssl;  
2.  
3.import java.io.BufferedReader;  
4.import java.io.FileInputStream;  
5.import java.io.IOException;  
6.import java.io.InputStreamReader;  
7.import java.io.PrintWriter;  
8.import java.net.ServerSocket;  
9.import java.net.Socket;  
10.import java.security.KeyStore;  
11.  
12.import javax.net.ServerSocketFactory;  
13.import javax.net.ssl.KeyManagerFactory;  
14.import javax.net.ssl.SSLContext;  
15.import javax.net.ssl.SSLServerSocket;  
16.  
17.public class SSLServer extends Thread \{  
18. private Socket socket;  
19.  
20. public SSLServer(Socket socket) \{  
21. this.socket = socket;  
22. \}  
23.  
24. public void run() \{  
25. try \{  
26. BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));  
27. PrintWriter writer = new PrintWriter(socket.getOutputStream());  
28.  
29. String data = reader.readLine();  
30. writer.println(data);  
31. writer.close();  
32. socket.close();  
33. \} catch (IOException e) \{  
34.  
35. \}  
36. \}  
37.  
38. private static String SERVER\_KEY\_STORE = "/Users/liweinan/projs/ssl/src/main/resources/META-INF/server\_ks";  
39. private static String SERVER\_KEY\_STORE\_PASSWORD = "123123";  
40.  
41. public static void main(String\[\] args) throws Exception \{  
42. System.setProperty("javax.net.ssl.trustStore", SERVER\_KEY\_STORE);  
43. SSLContext context = SSLContext.getInstance("TLS");  
44.  
45. KeyStore ks = KeyStore.getInstance("jceks");  
46. ks.load(new FileInputStream(SERVER\_KEY\_STORE), null);  
47. KeyManagerFactory kf = KeyManagerFactory.getInstance("SunX509");  
48. kf.init(ks, SERVER\_KEY\_STORE\_PASSWORD.toCharArray());  
49.  
50. context.init(kf.getKeyManagers(), null, null);  
51.  
52. ServerSocketFactory factory = context.getServerSocketFactory();  
53. ServerSocket \_socket = factory.createServerSocket(8443);  
54. ((SSLServerSocket) \_socket).setNeedClientAuth(false);  
55.  
56. while (true) \{  
57. new SSLServer(\_socket.accept()).start();  
58. \}  
59. \}  
60.\}  
package org.bluedash.tryssl;

import java.io.BufferedReader;  
import java.io.FileInputStream;  
import java.io.IOException;  
import java.io.InputStreamReader;  
import java.io.PrintWriter;  
import java.net.ServerSocket;  
import java.net.Socket;  
import java.security.KeyStore;

import javax.net.ServerSocketFactory;  
import javax.net.ssl.KeyManagerFactory;  
import javax.net.ssl.SSLContext;  
import javax.net.ssl.SSLServerSocket;

public class SSLServer extends Thread \{  
private Socket socket;

public SSLServer(Socket socket) \{  
this.socket = socket;  
\}

public void run() \{  
try \{  
BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));  
PrintWriter writer = new PrintWriter(socket.getOutputStream());

String data = reader.readLine();  
writer.println(data);  
writer.close();  
socket.close();  
\} catch (IOException e) \{

\}  
\}

private static String SERVER\_KEY\_STORE = "/Users/liweinan/projs/ssl/src/main/resources/META-INF/server\_ks";  
private static String SERVER\_KEY\_STORE\_PASSWORD = "123123";

public static void main(String\[\] args) throws Exception \{  
System.setProperty("javax.net.ssl.trustStore", SERVER\_KEY\_STORE);  
SSLContext context = SSLContext.getInstance("TLS");  
  
KeyStore ks = KeyStore.getInstance("jceks");  
ks.load(new FileInputStream(SERVER\_KEY\_STORE), null);  
KeyManagerFactory kf = KeyManagerFactory.getInstance("SunX509");  
kf.init(ks, SERVER\_KEY\_STORE\_PASSWORD.toCharArray());  
  
context.init(kf.getKeyManagers(), null, null);

ServerSocketFactory factory = context.getServerSocketFactory();  
ServerSocket \_socket = factory.createServerSocket(8443);  
((SSLServerSocket) \_socket).setNeedClientAuth(false);

while (true) \{  
new SSLServer(\_socket.accept()).start();  
\}  
\}  
\}

可以看到，服务端的Socket准备设置工作大大增加了，增加的代码的作用主要是将证书导入并进行使用。此外，所使用的Socket变成了SSLServerSocket，另外端口改到了8443（这个不是强制的，仅仅是为了遵守习惯）。另外，最重要的一点，服务端证书里面的CN一定和服务端的域名统一，我们的证书服务的域名是localhost，那么我们的客户端在连接服务端时一定也要用localhost来连接，否则根据SSL协议标准，域名与证书的CN不匹配，说明这个证书是不安全的，通信将无法正常运行。

有了服务端，我们原来的客户端就不能使用了，必须要走SSL协议。由于服务端的证书是我们自己生成的，没有任何受信任机构的签名，所以客户端是无法验证服务端证书的有效性的，通信必然会失败。所以我们需要为客户端创建一个保存所有信任证书的仓库，然后把服务端证书导进这个仓库。这样，当客户端连接服务端时，会发现服务端的证书在自己的信任列表中，就可以正常通信了。

因此现在我们要做的是生成一个客户端的证书仓库，因为keytool不能仅生成一个空白仓库，所以和服务端一样，我们还是生成一个证书加一个仓库（客户端证书加仓库）：

Bash代码  
1.keytool -genkey -v -alias bluedash-ssl-demo-client -keyalg RSA -keystore ./client\_ks -dname "CN=localhost,OU=cn,O=cn,L=cn,ST=cn,C=cn" -storepass client -keypass 456456  
keytool -genkey -v -alias bluedash-ssl-demo-client -keyalg RSA -keystore ./client\_ks -dname "CN=localhost,OU=cn,O=cn,L=cn,ST=cn,C=cn" -storepass client -keypass 456456

结果如下：

Bash代码  
1.Generating 1,024 bit RSA key pair and self-signed certificate (SHA1withRSA) with a validity of 90 days  
2. for: CN=localhost, OU=cn, O=cn, L=cn, ST=cn, C=cn  
3.\[Storing ./client\_ks\]  
Generating 1,024 bit RSA key pair and self-signed certificate (SHA1withRSA) with a validity of 90 days  
for: CN=localhost, OU=cn, O=cn, L=cn, ST=cn, C=cn  
\[Storing ./client\_ks\]

接下来，我们要把服务端的证书导出来，并导入到客户端的仓库。第一步是导出服务端的证书：

Bash代码  
1.keytool -export -alias bluedash-ssl-demo-server -keystore ./server\_ks -file server\_key.cer  
keytool -export -alias bluedash-ssl-demo-server -keystore ./server\_ks -file server\_key.cer

执行结果如下：

Bash代码  
1.Enter keystore password: server  
2.Certificate stored in file <server\_key.cer>  
Enter keystore password: server  
Certificate stored in file <server\_key.cer>

然后是把导出的证书导入到客户端证书仓库：

Bash代码  
1.keytool -import -trustcacerts -alias bluedash-ssl-demo-server -file ./server\_key.cer -keystore ./client\_ks  
keytool -import -trustcacerts -alias bluedash-ssl-demo-server -file ./server\_key.cer -keystore ./client\_ks

结果如下：

Bash代码  
1.Enter keystore password: client  
2.Owner: CN=localhost, OU=cn, O=cn, L=cn, ST=cn, C=cn  
3.Issuer: CN=localhost, OU=cn, O=cn, L=cn, ST=cn, C=cn  
4.Serial number: 4c57c7de  
5.Valid from: Tue Aug 03 15:40:14 CST 2010 until: Mon Nov 01 15:40:14 CST 2010  
6.Certificate fingerprints:  
7. MD5: FC:D4:8B:36:3F:1B:30:EA:6D:63:55:4F:C7:68:3B:0C  
8. SHA1: E1:54:2F:7C:1A:50:F5:74:AA:63:1E:F9:CC:B1:1C:73:AA:34:8A:C4  
9. Signature algorithm name: SHA1withRSA  
10. Version: 3  
11.Trust this certificate? \[no\]: yes  
12.Certificate was added to keystore  
Enter keystore password: client  
Owner: CN=localhost, OU=cn, O=cn, L=cn, ST=cn, C=cn  
Issuer: CN=localhost, OU=cn, O=cn, L=cn, ST=cn, C=cn  
Serial number: 4c57c7de  
Valid from: Tue Aug 03 15:40:14 CST 2010 until: Mon Nov 01 15:40:14 CST 2010  
Certificate fingerprints:  
MD5: FC:D4:8B:36:3F:1B:30:EA:6D:63:55:4F:C7:68:3B:0C  
SHA1: E1:54:2F:7C:1A:50:F5:74:AA:63:1E:F9:CC:B1:1C:73:AA:34:8A:C4  
Signature algorithm name: SHA1withRSA  
Version: 3  
Trust this certificate? \[no\]: yes  
Certificate was added to keystore

好，准备工作做完了，我们来撰写客户端的代码：

Java代码  
1.package org.bluedash.tryssl;  
2.  
3.import java.io.BufferedReader;  
4.import java.io.InputStreamReader;  
5.import java.io.PrintWriter;  
6.import java.net.Socket;  
7.  
8.import javax.net.SocketFactory;  
9.import javax.net.ssl.SSLSocketFactory;  
10.  
11.public class SSLClient \{  
12.  
13. private static String CLIENT\_KEY\_STORE = "/Users/liweinan/projs/ssl/src/main/resources/META-INF/client\_ks";  
14.  
15. public static void main(String\[\] args) throws Exception \{  
16. // Set the key store to use for validating the server cert.  
17. System.setProperty("javax.net.ssl.trustStore", CLIENT\_KEY\_STORE);  
18.  
19. System.setProperty("javax.net.debug", "ssl,handshake");  
20.  
21. SSLClient client = new SSLClient();  
22. Socket s = client.clientWithoutCert();  
23.  
24. PrintWriter writer = new PrintWriter(s.getOutputStream());  
25. BufferedReader reader = new BufferedReader(new InputStreamReader(s  
26. .getInputStream()));  
27. writer.println("hello");  
28. writer.flush();  
29. System.out.println(reader.readLine());  
30. s.close();  
31. \}  
32.  
33. private Socket clientWithoutCert() throws Exception \{  
34. SocketFactory sf = SSLSocketFactory.getDefault();  
35. Socket s = sf.createSocket("localhost", 8443);  
36. return s;  
37. \}  
38.\}  
package org.bluedash.tryssl;

import java.io.BufferedReader;  
import java.io.InputStreamReader;  
import java.io.PrintWriter;  
import java.net.Socket;

import javax.net.SocketFactory;  
import javax.net.ssl.SSLSocketFactory;

public class SSLClient \{

private static String CLIENT\_KEY\_STORE = "/Users/liweinan/projs/ssl/src/main/resources/META-INF/client\_ks";

public static void main(String\[\] args) throws Exception \{  
// Set the key store to use for validating the server cert.  
System.setProperty("javax.net.ssl.trustStore", CLIENT\_KEY\_STORE);  
  
System.setProperty("javax.net.debug", "ssl,handshake");

SSLClient client = new SSLClient();  
Socket s = client.clientWithoutCert();

PrintWriter writer = new PrintWriter(s.getOutputStream());  
BufferedReader reader = new BufferedReader(new InputStreamReader(s  
.getInputStream()));  
writer.println("hello");  
writer.flush();  
System.out.println(reader.readLine());  
s.close();  
\}

private Socket clientWithoutCert() throws Exception \{  
SocketFactory sf = SSLSocketFactory.getDefault();  
Socket s = sf.createSocket("localhost", 8443);  
return s;  
\}  
\}

可以看到，除了把一些类变成SSL通信类以外，客户端也多出了使用信任证书仓库的代码。以上，我们便完成了SSL单向握手通信。即：客户端验证服务端的证书，服务端不认证客户端的证书。

以上便是Java环境下SSL单向握手的全过程。因为我们在客户端设置了日志输出级别为DEBUG：

Java代码  
1.System.setProperty("javax.net.debug", "ssl,handshake");  
System.setProperty("javax.net.debug", "ssl,handshake");

因此我们可以看到SSL通信的全过程，这些日志可以帮助我们更具体地了解通过SSL协议建立网络连接时的全过程。

结合日志，我们来看一下SSL双向认证的全过程：

第一步: 客户端发送ClientHello消息，发起SSL连接请求，告诉服务器自己支持的SSL选项（加密方式等）。

Bash代码  
1.\*\*\* ClientHello, TLSv1  
\*\*\* ClientHello, TLSv1

第二步: 服务器响应请求，回复ServerHello消息，和客户端确认SSL加密方式：

Bash代码  
1.\*\*\* ServerHello, TLSv1  
\*\*\* ServerHello, TLSv1

第三步: 服务端向客户端发布自己的公钥。

第四步: 客户端与服务端的协通沟通完毕，服务端发送ServerHelloDone消息：

Bash代码  
1.\*\*\* ServerHelloDone  
\*\*\* ServerHelloDone

第五步: 客户端使用服务端给予的公钥，创建会话用密钥（SSL证书认证完成后，为了提高性能，所有的信息交互就可能会使用对称加密算法），并通过ClientKeyExchange消息发给服务器：

Bash代码  
1.\*\*\* ClientKeyExchange, RSA PreMasterSecret, TLSv1  
\*\*\* ClientKeyExchange, RSA PreMasterSecret, TLSv1

第六步： 客户端通知服务器改变加密算法，通过ChangeCipherSpec消息发给服务端：

Bash代码  
1.main, WRITE: TLSv1 Change Cipher Spec, length = 1  
main, WRITE: TLSv1 Change Cipher Spec, length = 1

第七步： 客户端发送Finished消息，告知服务器请检查加密算法的变更请求：

Bash代码  
1.\*\*\* Finished  
\*\*\* Finished

第八步：服务端确认算法变更，返回ChangeCipherSpec消息

Bash代码  
1.main, READ: TLSv1 Change Cipher Spec, length = 1  
main, READ: TLSv1 Change Cipher Spec, length = 1

第九步：服务端发送Finished消息，加密算法生效：

Bash代码  
1.\*\*\* Finished  
\*\*\* Finished

那么如何让服务端也认证客户端的身份，即双向握手呢？其实很简单，在服务端代码中，把这一行：

Java代码  
1.((SSLServerSocket) \_socket).setNeedClientAuth(false);  
((SSLServerSocket) \_socket).setNeedClientAuth(false);

改成：

Java代码  
1.((SSLServerSocket) \_socket).setNeedClientAuth(true);  
((SSLServerSocket) \_socket).setNeedClientAuth(true);

就可以了。但是，同样的道理，现在服务端并没有信任客户端的证书，因为客户端的证书也是自己生成的。所以，对于服务端，需要做同样的工作：把客户端的证书导出来，并导入到服务端的证书仓库：

Bash代码  
1.keytool -export -alias bluedash-ssl-demo-client -keystore ./client\_ks -file client\_key.cer  
2.Enter keystore password: client  
3.Certificate stored in file <client\_key.cer>  
keytool -export -alias bluedash-ssl-demo-client -keystore ./client\_ks -file client\_key.cer  
Enter keystore password: client  
Certificate stored in file <client\_key.cer>

Bash代码  
1.keytool -import -trustcacerts -alias bluedash-ssl-demo-client -file ./client\_key.cer -keystore ./server\_ks  
2.Enter keystore password: server  
3.Owner: CN=localhost, OU=cn, O=cn, L=cn, ST=cn, C=cn  
4.Issuer: CN=localhost, OU=cn, O=cn, L=cn, ST=cn, C=cn  
5.Serial number: 4c57c80b  
6.Valid from: Tue Aug 03 15:40:59 CST 2010 until: Mon Nov 01 15:40:59 CST 2010  
7.Certificate fingerprints:  
8. MD5: DB:91:F4:1E:65:D1:81:F2:1E:A6:A3:55:3F:E8:12:79  
9. SHA1: BF:77:56:61:04:DD:95:FC:E5:84:48:5C:BE:60:AF:02:96:A2:E1:E2  
10. Signature algorithm name: SHA1withRSA  
11. Version: 3  
12.Trust this certificate? \[no\]: yes  
13.Certificate was added to keystore  
keytool -import -trustcacerts -alias bluedash-ssl-demo-client -file ./client\_key.cer -keystore ./server\_ks  
Enter keystore password: server  
Owner: CN=localhost, OU=cn, O=cn, L=cn, ST=cn, C=cn  
Issuer: CN=localhost, OU=cn, O=cn, L=cn, ST=cn, C=cn  
Serial number: 4c57c80b  
Valid from: Tue Aug 03 15:40:59 CST 2010 until: Mon Nov 01 15:40:59 CST 2010  
Certificate fingerprints:  
MD5: DB:91:F4:1E:65:D1:81:F2:1E:A6:A3:55:3F:E8:12:79  
SHA1: BF:77:56:61:04:DD:95:FC:E5:84:48:5C:BE:60:AF:02:96:A2:E1:E2  
Signature algorithm name: SHA1withRSA  
Version: 3  
Trust this certificate? \[no\]: yes  
Certificate was added to keystore

完成了证书的导入，还要在客户端需要加入一段代码，用于在连接时，客户端向服务端出示自己的证书：

Java代码  
1.package org.bluedash.tryssl;  
2.  
3.import java.io.BufferedReader;  
4.import java.io.FileInputStream;  
5.import java.io.InputStreamReader;  
6.import java.io.PrintWriter;  
7.import java.net.Socket;  
8.import java.security.KeyStore;  
9.import javax.net.SocketFactory;  
10.import javax.net.ssl.KeyManagerFactory;  
11.import javax.net.ssl.SSLContext;  
12.import javax.net.ssl.SSLSocketFactory;  
13.  
14.public class SSLClient \{  
15. private static String CLIENT\_KEY\_STORE = "/Users/liweinan/projs/ssl/src/main/resources/META-INF/client\_ks";  
16. private static String CLIENT\_KEY\_STORE\_PASSWORD = "456456";  
17.  
18. public static void main(String\[\] args) throws Exception \{  
19. // Set the key store to use for validating the server cert.  
20. System.setProperty("javax.net.ssl.trustStore", CLIENT\_KEY\_STORE);  
21. System.setProperty("javax.net.debug", "ssl,handshake");  
22. SSLClient client = new SSLClient();  
23. Socket s = client.clientWithCert();  
24.  
25. PrintWriter writer = new PrintWriter(s.getOutputStream());  
26. BufferedReader reader = new BufferedReader(new InputStreamReader(s.getInputStream()));  
27. writer.println("hello");  
28. writer.flush();  
29. System.out.println(reader.readLine());  
30. s.close();  
31. \}  
32.  
33. private Socket clientWithoutCert() throws Exception \{  
34. SocketFactory sf = SSLSocketFactory.getDefault();  
35. Socket s = sf.createSocket("localhost", 8443);  
36. return s;  
37. \}  
38.  
39. private Socket clientWithCert() throws Exception \{  
40. SSLContext context = SSLContext.getInstance("TLS");  
41. KeyStore ks = KeyStore.getInstance("jceks");  
42.  
43. ks.load(new FileInputStream(CLIENT\_KEY\_STORE), null);  
44. KeyManagerFactory kf = KeyManagerFactory.getInstance("SunX509");  
45. kf.init(ks, CLIENT\_KEY\_STORE\_PASSWORD.toCharArray());  
46. context.init(kf.getKeyManagers(), null, null);  
47.  
48. SocketFactory factory = context.getSocketFactory();  
49. Socket s = factory.createSocket("localhost", 8443);  
50. return s;  
51. \}  
52.\}  
package org.bluedash.tryssl;

import java.io.BufferedReader;  
import java.io.FileInputStream;  
import java.io.InputStreamReader;  
import java.io.PrintWriter;  
import java.net.Socket;  
import java.security.KeyStore;  
import javax.net.SocketFactory;  
import javax.net.ssl.KeyManagerFactory;  
import javax.net.ssl.SSLContext;  
import javax.net.ssl.SSLSocketFactory;

public class SSLClient \{  
private static String CLIENT\_KEY\_STORE = "/Users/liweinan/projs/ssl/src/main/resources/META-INF/client\_ks";  
private static String CLIENT\_KEY\_STORE\_PASSWORD = "456456";  
  
public static void main(String\[\] args) throws Exception \{  
// Set the key store to use for validating the server cert.  
System.setProperty("javax.net.ssl.trustStore", CLIENT\_KEY\_STORE);  
System.setProperty("javax.net.debug", "ssl,handshake");  
SSLClient client = new SSLClient();  
Socket s = client.clientWithCert();  
  
PrintWriter writer = new PrintWriter(s.getOutputStream());  
BufferedReader reader = new BufferedReader(new InputStreamReader(s.getInputStream()));  
writer.println("hello");  
writer.flush();  
System.out.println(reader.readLine());  
s.close();  
\}

private Socket clientWithoutCert() [ tb][tb]hrows Exception \{  
SocketFactory sf = SSLSocketFactory.getDefault();  
Socket s = sf.createSocket("localhost", 8443);  
return s;  
\}

private Socket clientWithCert() throws Exception \{  
SSLContext context = SSLContext.getInstance("TLS");  
KeyStore ks = KeyStore.getInstance("jceks");  
  
ks.load(new FileInputStream(CLIENT\_KEY\_STORE), null);  
KeyManagerFactory kf = KeyManagerFactory.getInstance("SunX509");  
kf.init(ks, CLIENT\_KEY\_STORE\_PASSWORD.toCharArray());  
context.init(kf.getKeyManagers(), null, null);  
  
SocketFactory factory = context.getSocketFactory();  
Socket s = factory.createSocket("localhost", 8443);  
return s;  
\}  
\}

通过比对单向认证的日志输出，我们可以发现双向认证时，多出了服务端认证客户端证书的步骤：

Bash代码  
1.\*\*\* CertificateRequest  
2.Cert Types: RSA, DSS  
3.Cert Authorities:  
4.<CN=localhost, OU=cn, O=cn, L=cn, ST=cn, C=cn>  
5.<CN=localhost, OU=cn, O=cn, L=cn, ST=cn, C=cn>  
6.\*\*\* ServerHelloDone  
\*\*\* CertificateRequest  
Cert Types: RSA, DSS  
Cert Authorities:  
<CN=localhost, OU=cn, O=cn, L=cn, ST=cn, C=cn>  
<CN=localhost, OU=cn, O=cn, L=cn, ST=cn, C=cn>  
\*\*\* ServerHelloDone

Bash代码  
1.\*\*\* CertificateVerify  
2.main, WRITE: TLSv1 Handshake, length = 134  
3.main, WRITE: TLSv1 Change Cipher Spec, length = 1  
\*\*\* CertificateVerify  
main, WRITE: TLSv1 Handshake, length = 134  
main, WRITE: TLSv1 Change Cipher Spec, length = 1

在 @\*\*\* ServerHelloDone@ 之前，服务端向客户端发起了需要证书的请求 @\*\*\* CertificateRequest@ 。

在客户端向服务端发出 @Change Cipher Spec@ 请求之前，多了一步客户端证书认证的过程 @\*\*\* CertificateVerify@ 。

客户端与服务端互相认证证书的情景

[SSL_Java]: http://www.blogjava.net/tbwshc/archive/2012/07/13/383009.html
[tb]: http://www.tbwshc.com/