关于SSL/TLS/JSSE的介绍：
1）SSL/TLS协议运行机制
2）图解SSL/TLS协议
3）使用wireshark观察SSL/TLS握手过程
4）SSL/TLS的Java实现--JSSE

（一）使用keytool创建密钥库

使用双向认证的SSL/TLS协议通信，客户端和服务器端都要设置用于证实自己身份的安全证书，并且还要设置信任对方的哪些安全证书。
理论上一共需要准备四个文件，两个keystore文件和两个truststore文件。
通信双方分别拥有一个keystore和一个truststore，keystore用于存放自己的密钥和公钥，truststore用于存放所有需要信任方的公钥。

首先使用JDK自带的keytool工具来生成keystore和truststore。这里使用的Java版本是1.7。
1）创建server的keystore文件，生成server的公钥/私钥密钥对。需要指定keystore的密码(storepass)和密钥对的密码(keypass)。
访问keystore需要storepass。访问密钥对需要keypass。

C:\Program Files\Java\jre7\bin>keytool -genkey -alias catserver -keyalg rsa -keysize 1024 -sigalg sha256withrsa -keypass catserver -keystore c:\_tmp\catserver.keystore -storepass catserverksWhat is your first and last name?[Unknown]: catWhat is the name of your organizational unit?[Unknown]: catWhat is the name of your organization?[Unknown]: catWhat is the name of your City or Locality?[Unknown]: catWhat is the name of your State or Province?[Unknown]: catWhat is the two-letter country code for this unit?[Unknown]: ctIs CN=cat, OU=cat, O=cat, L=cat, ST=cat, C=ct correct?[no]: y

2）创建client的keystore文件。同样需要指定keystore的密码和密钥对的密码。

C:\Program Files\Java\jre7\bin>keytool -genkey -alias foxclient -keyalg dsa -keysize 512 -sigalg sha1withdsa -keypass foxclient -keystore c:\_tmp\foxclient.keystore -storepass foxclientksWhat is your first and last name?[Unknown]: foxWhat is the name of your organizational unit?[Unknown]: foxWhat is the name of your organization?[Unknown]: foxWhat is the name of your City or Locality?[Unknown]: foxWhat is the name of your State or Province?[Unknown]: foxWhat is the two-letter country code for this unit?[Unknown]: fxIs CN=fox, OU=fox, O=fox, L=fox, ST=fox, C=fx correct?[no]: y

3）从server的keystore中导出server的证书（其中包括server的公钥）。

C:\Program Files\Java\jre7\bin>keytool -export -alias catserver -keystore c:\_tmp\catserver.keystore -storepass catserverks -file c:\_tmp\catserver.cerCertificate stored in file <c:\_tmp\catserver.cer>

4）从client的keystore中导出client的证书（其中包括client的公钥）。

C:\Program Files\Java\jre7\bin>keytool -export -alias foxclient -keystore c:\_tmp\foxclient.keystore -storepass foxclientks -file c:\_tmp\foxclient.cerCertificate stored in file <c:\_tmp\foxclient.cer>

5）创建server的truststore文件并导入client的证书（其中包括client的公钥）。

C:\Program Files\Java\jre7\bin>keytool -import -alias foxclient -keystore c:\_tmp\catservertrust.keystore -storepass catservertrustks -file c:\_tmp\foxclient.cerOwner: CN=fox, OU=fox, O=fox, L=fox, ST=fox, C=fxIssuer: CN=fox, OU=fox, O=fox, L=fox, ST=fox, C=fxSerial number: 6eaf996fValid from: Wed Nov 05 16:15:41 CST 2014 until: Tue Feb 03 16:15:41 CST 2015Certificate fingerprints:MD5: B5:B6:92:66:84:92:A0:C2:F5:40:39:25:F8:66:2A:17SHA1: 07:42:A3:1A:49:7B:C9:34:4B:6B:FA:37:6C:20:98:D4:20:13:7C:91SHA256: 37:A5:00:A3:13:00:DE:99:3B:08:47:F6:1E:8A:05:F1:4A:B2:C6:22:20:E1:AF:0E:05:B2:CE:E0:2F:94:B6:94Signature algorithm name: SHA1withDSAVersion: 3Extensions:#1: ObjectId: 2.5.29.14 Criticality=falseSubjectKeyIdentifier [KeyIdentifier [0000: 69 3E 6A D0 B5 B1 1F BD 48 46 E1 A4 6C 1F 71 90 i>j.....HF..l.q.0010: 29 06 3B 32 ).;2]]Trust this certificate? [no]: yCertificate was added to keystore

6）创建client的truststore文件并导入server的证书（其中包括server的公钥）。

C:\Program Files\Java\jre7\bin>keytool -import -alias catserver -keystore c:\_tmp\foxclienttrust.keystore -storepass foxclienttrustks -file c:\_tmp\catserver.cerOwner: CN=cat, OU=cat, O=cat, L=cat, ST=cat, C=ctIssuer: CN=cat, OU=cat, O=cat, L=cat, ST=cat, C=ctSerial number: 3e421457Valid from: Wed Nov 05 16:13:52 CST 2014 until: Tue Feb 03 16:13:52 CST 2015Certificate fingerprints:MD5: 20:44:7C:E5:30:E6:7A:21:C2:49:64:77:E1:3A:A0:77SHA1: 8B:02:D2:BE:98:2F:99:94:08:47:E2:96:EC:05:1B:5D:B1:8F:30:2FSHA256: A6:66:85:F4:C2:B2:06:4E:2E:40:D8:52:84:6E:85:2B:5B:BB:C3:B0:9C:31:92:99:F5:91:5D:83:67:C8:4D:D8Signature algorithm name: SHA256withRSAVersion: 3Extensions:#1: ObjectId: 2.5.29.14 Criticality=falseSubjectKeyIdentifier [KeyIdentifier [0000: F5 91 E6 14 EE EF 5F 24 4F AC 6F A6 B8 36 A6 11 ......_$O.o..6..0010: 2B 5C DF 04 +\..]]Trust this certificate? [no]: yCertificate was added to keystore

keysize
如果加密算法是rsa，key size范围512->16384 bits，并且必须是64的倍数。
如果加密算法是dsa，key size范围512->1024 bits，并且必须是64的倍数。

sigalg
如果加密算法是rsa，签名算法可以是md5withrsa/sha1withrsa/sha256withrsa/sha384withrsa/sha512withrsa
如果加密算法是dsa，签名算法可以是sha1withdsa

如果熟悉Java的socket编程，就会发现使用JSSE进行SSL/TLS编程其实和它很相似。
区别在于ServerSocket对象换成了SSLServerSocket，Socket对象换成了SSLSocket对象。

（二）server端处理流程和代码

处理流程：
1）加载server的keystore文件，需要指定keystore的密码(storepass)。
KeyStore类型有如下三种：
jceks - The proprietary keystore implementation provided by the SunJCE provider.
jks - The proprietary keystore implementation provided by the SUN provider.
pkcs12 - The transfer syntax for personal identity information as defined in PKCS #12.

2）加载server的truststore文件，需要指定truststore的密码(storepass)。

3) 创建KeyManagerFactory对象并用1）中加载的keystore和server密钥对的密码(keypass)来初始化。

4) 创建TrustManagerFactory对象并用2）中加载的truststore来初始化。truststore中存的是client的公钥，不需要keypass也可以访问。

5）创建SSLContext并用3）和4）中创建的KeyManagerFactory和TrustManagerFactory对象来初始化。
http://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#SSLContext
创建SSLContext是需要给出SSLContext Algorithms。上面这个链接中给出了合法的SSLContext Algorithms，有如下可用值。
SSL - Supports some version of SSL; may support other versions
SSLv2 - Supports SSL version 2 or later; may support other versions
SSLv3 - Supports SSL version 3; may support other versions
TLS - Supports some version of TLS; may support other versions
TLSv1 - Supports RFC 2246: TLS version 1.0 ; may support other versions
TLSv1.1 - Supports RFC 4346: TLS version 1.1 ; may support other versions
TLSv1.2 - Supports RFC 5246: TLS version 1.2 ; may support other versions

6）创建SSLServerSocketFactory，在指定的端口上创建SSLServerSocket并设定需要客户端证书：setNeedClientAuth(true)

7）在SSLServerSocket对象上调用accept()方法等待客户端的连接。
客户端连上来之后这个函数会返回一个SSLSocket对象，在这个对象的输入输出流上进行读写。
在这个SSLSocket对象上可以添加一个HandshakeCompletedListener的监听器，SSL/TLS握手结束后这个监听器的handshakeCompleted方法就会被调用。
客户端有三种方法会触发握手：
- 显式调用startHandshake方法/calling startHandshake which explicitly begins handshakes, or
- 在socket对象上进行read或write操作/any attempt to read or write application data on this socket causes an implicit handshake, or
- 在socket对象上调用getSession方法/a call to getSession tries to set up a session if there is no currently valid session, and an implicit handshake is done.

package learning.net.ssl;import java.io.BufferedReader;import java.io.FileInputStream;import java.io.IOException;import java.io.InputStreamReader;import java.io.PrintWriter;import java.net.Socket;import java.security.KeyStore;import java.security.cert.X509Certificate;import javax.net.ssl.HandshakeCompletedEvent;import javax.net.ssl.HandshakeCompletedListener;import javax.net.ssl.KeyManagerFactory;import javax.net.ssl.SSLContext;import javax.net.ssl.SSLPeerUnverifiedException;import javax.net.ssl.SSLServerSocket;import javax.net.ssl.SSLServerSocketFactory;import javax.net.ssl.SSLSocket;import javax.net.ssl.TrustManagerFactory;public class CatServer implements Runnable, HandshakeCompletedListener {    public static final int SERVER_PORT = 11123;    private final Socket _s;    private String peerCerName;    public CatServer(Socket s) {        _s = s;    }    public static void main(String[] args) throws Exception {        String serverKeyStoreFile = "c:\\_tmp\\catserver.keystore";        String serverKeyStorePwd = "catserverks";        String catServerKeyPwd = "catserver";        String serverTrustKeyStoreFile = "c:\\_tmp\\catservertrust.keystore";        String serverTrustKeyStorePwd = "catservertrustks";        KeyStore serverKeyStore = KeyStore.getInstance("JKS");        serverKeyStore.load(new FileInputStream(serverKeyStoreFile), serverKeyStorePwd.toCharArray());        KeyStore serverTrustKeyStore = KeyStore.getInstance("JKS");        serverTrustKeyStore.load(new FileInputStream(serverTrustKeyStoreFile), serverTrustKeyStorePwd.toCharArray());        KeyManagerFactory kmf = KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm());        kmf.init(serverKeyStore, catServerKeyPwd.toCharArray());        TrustManagerFactory tmf = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());        tmf.init(serverTrustKeyStore);        SSLContext sslContext = SSLContext.getInstance("TLSv1");        sslContext.init(kmf.getKeyManagers(), tmf.getTrustManagers(), null);        SSLServerSocketFactory sslServerSocketFactory = sslContext.getServerSocketFactory();        SSLServerSocket sslServerSocket = (SSLServerSocket) sslServerSocketFactory.createServerSocket(SERVER_PORT);        sslServerSocket.setNeedClientAuth(true);        while (true) {            SSLSocket s = (SSLSocket)sslServerSocket.accept();            CatServer cs = new CatServer(s);            s.addHandshakeCompletedListener(cs);            new Thread(cs).start();        }    }    @Override    public void run() {        try {            BufferedReader reader = new BufferedReader(new InputStreamReader(_s.getInputStream()));            PrintWriter writer = new PrintWriter(_s.getOutputStream(), true);            writer.println("Welcome~, enter exit to leave.");            String s;            while ((s = reader.readLine()) != null && !s.trim().equalsIgnoreCase("exit")) {                writer.println("Echo: " + s);            }            writer.println("Bye~, " + peerCerName);        } catch (Exception e) {            e.printStackTrace();        } finally {            try {                _s.close();            } catch (IOException e) {                e.printStackTrace();            }        }    }    @Override    public void handshakeCompleted(HandshakeCompletedEvent event) {        try {            X509Certificate cert = (X509Certificate) event.getPeerCertificates()[0];            peerCerName = cert.getSubjectX500Principal().getName();        } catch (SSLPeerUnverifiedException ex) {            ex.printStackTrace();        }    }}

（三）client端处理流程和代码
处理流程：（1~5和server相同）
1）加载client的keystore文件。

2）加载client的truststore文件。

3) 创建KeyManagerFactory对象并初始化。

4) 创建TrustManagerFactory对象并初始化。truststore中存的是server的公钥，不需要keypass也可以访问。

5）创建SSLContext并用3）和4）中创建的KeyManagerFactory和TrustManagerFactory对象来初始化。

6）创建SSLSocketFactory，在指定的网络地址和端口上创建SSLSocket。

7）在这个SSLSocket对象的输入输出流上进行读写。

package learning.net.ssl;import java.io.BufferedReader;import java.io.FileInputStream;import java.io.IOException;import java.io.InputStreamReader;import java.io.PrintWriter;import java.net.Socket;import java.security.KeyStore;import javax.net.ssl.KeyManagerFactory;import javax.net.ssl.SSLContext;import javax.net.ssl.SSLSocketFactory;import javax.net.ssl.TrustManagerFactory;public class FoxClient {    public static void main(String[] args) throws Exception {        String clientKeyStoreFile = "c:\\_tmp\\foxclient.keystore";        String clientKeyStorePwd = "foxclientks";        String foxclientKeyPwd = "foxclient";        String clientTrustKeyStoreFile = "c:\\_tmp\\foxclienttrust.keystore";        String clientTrustKeyStorePwd = "foxclienttrustks";        KeyStore clientKeyStore = KeyStore.getInstance("JKS");        clientKeyStore.load(new FileInputStream(clientKeyStoreFile), clientKeyStorePwd.toCharArray());        KeyStore clientTrustKeyStore = KeyStore.getInstance("JKS");        clientTrustKeyStore.load(new FileInputStream(clientTrustKeyStoreFile), clientTrustKeyStorePwd.toCharArray());        KeyManagerFactory kmf = KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm());        kmf.init(clientKeyStore, foxclientKeyPwd.toCharArray());        TrustManagerFactory tmf = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());        tmf.init(clientTrustKeyStore);        SSLContext sslContext = SSLContext.getInstance("TLSv1");        sslContext.init(kmf.getKeyManagers(), tmf.getTrustManagers(), null);                SSLSocketFactory socketFactory = sslContext.getSocketFactory();        Socket socket = socketFactory.createSocket("localhost", CatServer.SERVER_PORT);                PrintWriter out = new PrintWriter(socket.getOutputStream(), true);        BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));                send("hello", out);        send("exit", out);        receive(in);        socket.close();    }        public static void send(String s, PrintWriter out) throws IOException {        System.out.println("Sending: " + s);             out.println(s);    }    public static void receive(BufferedReader in) throws IOException {        String s;        while ((s = in.readLine()) != null) {            System.out.println("Reveived: " + s);        }    }}

Java-JSSE-SSL/TLS编程代码实例-双向认证