对等计算实践: P2P 遇上 SSL

   // Each peer has an identity that must be locally (but not globally)
   // unique.  This identity and its associated public and private keys
   // are stored in a keystore and protected by a password.  Each
   // peer also has a name that must be globally unique.
   String stringIdentity = null;
   String stringPassword = null;
   String stringName = null;

   // The code that prompts the user for his/her identity
   // and password goes here.  the user's name is
   // generated (if necessary) later.

   // Create home directory.  This is a very portable way
   // to create a home directory, but it has its problems --
   // the various flavors of Microsoft Windows put the directory
   // in widely different locations in the directory hierarchy.
   String stringHome = System.getProperty("user.home") + File.separator + "p2p";
   File fileHome = new File(stringHome);
   if (fileHome.exists() == false)
     fileHome.mkdirs();

   // Create keystore.  We must run an external process to create the
   // keystore, because the security APIs don't expose enough
   // functionality to do this inline.  I haven't tested this widely enough
   // to know how portable this code is, but it works on everything I
   // tried it on.
   String stringKeyStore = stringHome + File.separator + "keystore";
   File fileKeyStore = new File(stringKeyStore);
   if (fileKeyStore.exists() == false)
   {
     System.out.println("Creating keystore...");
     byte [] arb = new byte [16];
     SecureRandom securerandom = SecureRandom.getInstance("SHA1PRNG");
     securerandom.nextBytes(arb);
     stringName = new String(Base64.encode(arb));
     String [] arstringCommand = new String []
     {
       System.getProperty("java.home") + File.separator + "bin" + File.separator + "keytool",
       "-genkey",
       "-alias", stringIdentity,
       "-keyalg", "RSA",
       "-keysize", "1024",
       "-dname", "CN=" + stringName,
       "-keystore", stringHome + File.separator + "keystore",
       "-keypass", stringPassword,
       "-storetype", "JCEKS",
       "-storepass", stringPassword
     };
     Process process = Runtime.getRuntime().exec(arstringCommand);
     process.waitFor();
     InputStream inputstream2 = process.getInputStream();
     IOUtils.copy(inputstream2, System.out);
     InputStream inputstream3 = process.getErrorStream();
     IOUtils.copy(inputstream3, System.out);
     if (process.exitValue() != 0)
       System.exit(-1);
   }

   // Once the application has created/located the keystore, it
   // opens it and creates a KeyStore instance from the data
   // in it.
   char [] archPassword = stringPassword.toCharArray();
   FileInputStream fileinputstream = new FileInputStream(stringHome + File.separator +

     "keystore");
   KeyStore keystore = KeyStore.getInstance("JCEKS");
   try
   {
     keystore.load(fileinputstream, archPassword);
   }
   catch (IOException ioexception)
   {
     System.out.println("Cannot load keystore.  Password may be wrong.");
     System.exit(-3);
   }
   if (keystore.containsAlias(stringIdentity) == false)
   {
     System.out.println("Cannot locate identity.");
     System.exit(-2);
   }

   // Create key manager.  The key manager holds this peer's
   // private key.
   KeyManagerFactory keymanagerfactory = KeyManagerFactory.getInstance("SunX509");
   keymanagerfactory.init(keystore, archPassword);
   KeyManager [] arkeymanager = keymanagerfactory.getKeyManagers();

   // Create trust manager.  The trust manager hold other peers'
   // certificates.
   TrustManagerFactory trustmanagerfactory = TrustManagerFactory.getInstance("SunX509");
   trustmanagerfactory.init(keystore);
   TrustManager [] artrustmanager = trustmanagerfactory.getTrustManagers();

   // Create SSL context.
   SSLContext sslcontext = SSLContext.getInstance("SSL");
   SecureRandom securerandom = SecureRandom.getInstance("SHA1PRNG");
   sslcontext.init(arkeymanager, artrustmanager, securerandom);

   // Create factories.
   m_socketfactory = sslcontext.getSocketFactory();
   m_serversocketfactory = sslcontext.getServerSocketFactory();
   m_keystore = keystore;