BAEL-2250: Adding files for the article on SSL handshake failure. (#5541)

* BAEL-2250: Adding files for the article on SSL handshake failure.

* BAEL-2250 cleanup formatting

* Applied review feedback on the article.

* Adding cipher suite and protocol selection in server and client

* Corrected some code conventions.

* Revert: BAEL-2250 cleanup formatting

core-java/src/main/java/com/baeldung/ssl/example/SimpleClient.java

@@ -0,0 +1,29 @@
+package com.baeldung.ssl.example;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.Socket;
+
+import javax.net.SocketFactory;
+import javax.net.ssl.SSLSocket;
+import javax.net.ssl.SSLSocketFactory;
+
+public class SimpleClient {
+    static void startClient(String host, int port) throws IOException {
+        SocketFactory factory = SSLSocketFactory.getDefault();
+        try (Socket connection = factory.createSocket(host, port)) {
+            ((SSLSocket) connection).setEnabledCipherSuites(
+              new String[] { "TLS_DHE_DSS_WITH_AES_256_CBC_SHA256"});
+            ((SSLSocket) connection).setEnabledProtocols(
+              new String[] { "TLSv1.2"});
+            BufferedReader input = new BufferedReader(
+              new InputStreamReader(connection.getInputStream()));
+            System.out.println(input.readLine());
+        }
+    }
+
+    public static void main(String[] args) throws IOException {
+        startClient("localhost", 1234);
+    }
+}

core-java/src/main/java/com/baeldung/ssl/example/SimpleServer.java

@@ -0,0 +1,34 @@
+package com.baeldung.ssl.example;
+
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.util.Date;
+
+import javax.net.ServerSocketFactory;
+import javax.net.ssl.SSLServerSocket;
+import javax.net.ssl.SSLServerSocketFactory;
+
+public class SimpleServer {
+    static void startServer(int port) throws IOException {
+        ServerSocketFactory factory = SSLServerSocketFactory.getDefault();
+        try (ServerSocket listener = factory.createServerSocket(port)) {
+            ((SSLServerSocket) listener).setNeedClientAuth(true);
+            ((SSLServerSocket) listener).setEnabledCipherSuites(
+              new String[] { "TLS_DHE_DSS_WITH_AES_256_CBC_SHA256"});
+            ((SSLServerSocket) listener).setEnabledProtocols(
+              new String[] { "TLSv1.2"});
+            while (true) {
+                try (Socket socket = listener.accept()) {
+                    PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
+                    out.println(new Date().toString());
+                }
+            }
+        }
+    }
+
+    public static void main(String[] args) throws IOException {
+        startServer(1234);
+    }
+}