Step 1 - Basics

Step 1 - Basics

Create a file called SSLConnect.java like the following:
 import java.net.*;

 import java.io.*;

 import java.security.*;

 import java.util.*;

 

 import ice.ssl.*;

 import ice.util.Defs;

 import ice.cert.*;

 

 public class SSLConnect {

     Socket sslconn;

     InputStream in;

     OutputStream out;

     private final static String TRUSTED_CA_FILE_NAME = "cacerts.crt";

 

     SSLConnect(String host, int port){

 

     ice.ssl.CertificateManager cm = new ice.ssl.CertificateManager();

     ice.ssl.CertificateManager.setCertificateManager(cm);

     

     //Install the list of trusted certificate authorities.

     try {

         java.io.InputStream in = this.getClass()

          .getResourceAsStream(TRUSTED_CA_FILE_NAME);

         cm.setCAList(ServerCertificateList.restoreListFromPEM(in));

         in.close();

     }

     catch (Exception ex) {

         System.err.println("Could not load root certificates");

     }

     

     //Make an SSL connection

     try{

         sslconn = new ice.ssl.SSLSocket(host,port);

         in = sslconn.getInputStream();

         out = sslconn.getOutputStream();

         String header = "GET / HTTP/1.0\nConnection: close\n\n";

         out.write(header.getBytes());

     } catch(UnknownHostException ex){

         System.err.println("No such host");

         ex.printStackTrace();

     }catch(IOException ex){

         System.err.println("Could not connect");

         ex.printStackTrace();

     }

 

     

     //Write respond from server to screen

     //(until connection closed)

     byte[] buffer = new byte[80];

     try{

         int numbytes = in.read(buffer);    

         while(numbytes != -1){

         System.out.print(new String(buffer, 0, numbytes)); 

         numbytes = in.read(buffer);

         }

     } catch(IOException ex){

         System.err.println("Could not recieve data");

     }

     }

     

     public static void main(String[] args){

     String host = args[0];

     int port = (new Integer(args[1])).intValue();

     SSLConnect sslwin = new SSLConnect(host,port);

     }

 }
 
The Import Statements

The ICEssl module implementation of the SSL protocol is in the package ice.ssl, and this package must be imported. In addition, java.net.* is imported because network facilities are used, and java.io.* for printing out messages. This simple example does not use any GUI libraries.

The main method is the following:
    public static void main(String[] args){

     String host = args[0];

     int port = (new Integer(args[1])).intValue();

     SSLConnect sslwin = new SSLConnect(host,port);

     }
 
This method parses the command line and creates an SSLConnect object that connects to a specific port on a host. All the functionality of this simple example takes place in the SSLConnect constructor.

Installing a Certificate Manager

In SSL it is mandatory for the server to authenticate itself. During this process the server sends a certificate and a digital signature the client must verify. This is the main purpose of the certificate manager. Before an SSL connection can take place, a certificate manager must be installed with a list of trusted root certificates from the CAs you trust. In the example directory the file cacerts.crt contains a number of PEM encoded X.509 certificates from the most common CAs.

First you install the certificate manager:
    ice.ssl.CertificateManager cm = new ice.ssl.CertificateManager();

    ice.ssl.CertificateManager.setCertificateManager(cm);
 
Then add a list of server side certificates to CertificateManager:
    try {

        java.io.InputStream in = this.getClass().

          getResourceAsStream(TRUSTED_CA_FILE_NAME);

        cm.setCAList(ServerCertificateList.restoreListFromPEM(in));

        in.close();

    }

    catch (Exception ex) {

        System.err.println("Could not load root certificates");

    }
 
Connecting to a Server

The SSLSocket class is a subclass of the java.net.Socket( ) class, so connecting to a server and communication with java.net.Socket( ) is done in the same way as for SSLSocket. The rest of the example code connects to a server and sends a HTTP request for the root of a Web server, and prints out the response from the server to the console.