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.InputStbreamReader;
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() tbhrows 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