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Android and self-signed ssl certificates

  • Autor:
  • Datum: 24.06.2010

Dealing with self-signed ssl certificates is a real pain, because it’s not that simple to add them in your app and let android accept them. But fortunately, there’s a workaround that uses an own SSLSocketFactory and an own TrustManager. With this, only your added site is beeing able to be called, so theres no security issue.

First you have to create the SSLFactory:

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.UnknownHostException;

import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSocket;
import javax.net.ssl.TrustManager;

import org.apache.http.conn.ConnectTimeoutException;
import org.apache.http.conn.scheme.LayeredSocketFactory;
import org.apache.http.conn.scheme.SocketFactory;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;

/**
 * This socket factory will create ssl socket that accepts self signed certificate
 * 
 * @author olamy
 * @version $Id: EasySSLSocketFactory.java 765355 2009-04-15 20:59:07Z evenisse $
 * @since 1.2.3
 */
public class EasySSLSocketFactory implements SocketFactory, LayeredSocketFactory {

    private SSLContext sslcontext = null;

    private static SSLContext createEasySSLContext() throws IOException {
        try {
            SSLContext context = SSLContext.getInstance("TLS");
            context.init(null, new TrustManager[] { new EasyX509TrustManager(null) }, null);
            return context;
        } catch (Exception e) {
            throw new IOException(e.getMessage());
        }
    }

    private SSLContext getSSLContext() throws IOException {
        if (this.sslcontext == null) {
            this.sslcontext = createEasySSLContext();
        }
        return this.sslcontext;
    }

    /**
     * @see org.apache.http.conn.scheme.SocketFactory#connectSocket(java.net.Socket, java.lang.String, int,
     *      java.net.InetAddress, int, org.apache.http.params.HttpParams)
     */
    public Socket connectSocket(Socket sock, String host, int port, InetAddress localAddress, int localPort,
            HttpParams params) throws IOException, UnknownHostException, ConnectTimeoutException {
        int connTimeout = HttpConnectionParams.getConnectionTimeout(params);
        int soTimeout = HttpConnectionParams.getSoTimeout(params);
        InetSocketAddress remoteAddress = new InetSocketAddress(host, port);
        SSLSocket sslsock = (SSLSocket) ((sock != null) ? sock : createSocket());

        if ((localAddress != null) || (localPort > 0)) {
            // we need to bind explicitly
            if (localPort < 0) {
                localPort = 0; // indicates "any"
            }
            InetSocketAddress isa = new InetSocketAddress(localAddress, localPort);
            sslsock.bind(isa);
        }

        sslsock.connect(remoteAddress, connTimeout);
        sslsock.setSoTimeout(soTimeout);
        return sslsock;

    }

    /**
     * @see org.apache.http.conn.scheme.SocketFactory#createSocket()
     */
    public Socket createSocket() throws IOException {
        return getSSLContext().getSocketFactory().createSocket();
    }

    /**
     * @see org.apache.http.conn.scheme.SocketFactory#isSecure(java.net.Socket)
     */
    public boolean isSecure(Socket socket) throws IllegalArgumentException {
        return true;
    }

    /**
     * @see org.apache.http.conn.scheme.LayeredSocketFactory#createSocket(java.net.Socket, java.lang.String, int,
     *      boolean)
     */
    public Socket createSocket(Socket socket, String host, int port, boolean autoClose) throws IOException,
            UnknownHostException {
        return getSSLContext().getSocketFactory().createSocket(socket, host, port, autoClose);
    }

    // -------------------------------------------------------------------
    // javadoc in org.apache.http.conn.scheme.SocketFactory says :
    // Both Object.equals() and Object.hashCode() must be overridden
    // for the correct operation of some connection managers
    // -------------------------------------------------------------------

    public boolean equals(Object obj) {
        return ((obj != null) && obj.getClass().equals(EasySSLSocketFactory.class));
    }

    public int hashCode() {
        return EasySSLSocketFactory.class.hashCode();
    }

}

And the TrustManager:

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;

import javax.net.ssl.TrustManager;
import javax.net.ssl.TrustManagerFactory;
import javax.net.ssl.X509TrustManager;

/**
 * @author olamy
 * @version $Id: EasyX509TrustManager.java 765355 2009-04-15 20:59:07Z evenisse $
 * @since 1.2.3
 */
public class EasyX509TrustManager implements X509TrustManager {

    private X509TrustManager standardTrustManager = null;

    /**
     * Constructor for EasyX509TrustManager.
     */
    public EasyX509TrustManager(KeyStore keystore) throws NoSuchAlgorithmException, KeyStoreException {
        super();
        TrustManagerFactory factory = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
        factory.init(keystore);
        TrustManager[] trustmanagers = factory.getTrustManagers();
        if (trustmanagers.length == 0) {
            throw new NoSuchAlgorithmException("no trust manager found");
        }
        this.standardTrustManager = (X509TrustManager) trustmanagers[0];
    }

    /**
     * @see javax.net.ssl.X509TrustManager#checkClientTrusted(X509Certificate[],String authType)
     */
    public void checkClientTrusted(X509Certificate[] certificates, String authType) throws CertificateException {
        standardTrustManager.checkClientTrusted(certificates, authType);
    }

    /**
     * @see javax.net.ssl.X509TrustManager#checkServerTrusted(X509Certificate[],String authType)
     */
    public void checkServerTrusted(X509Certificate[] certificates, String authType) throws CertificateException {
        if ((certificates != null) && (certificates.length == 1)) {
            certificates[0].checkValidity();
        } else {
            standardTrustManager.checkServerTrusted(certificates, authType);
        }
    }

    /**
     * @see javax.net.ssl.X509TrustManager#getAcceptedIssuers()
     */
    public X509Certificate[] getAcceptedIssuers() {
        return this.standardTrustManager.getAcceptedIssuers();
    }

}

(Both classes are from exchangeit with a small change on the EasySSLSocketFactory to work on android 2.2)

Now we have to do some other preparations and create a HttpClient that we can use to establish the connection:

//members
private ClientConnectionManager clientConnectionManager;
private HttpContext context;
private HttpParams params;







//constructor
public WebService(){
  setup();
}


//prepare for the https connection
//call this in the constructor of the class that does the connection if
//it's used multiple times
private void setup(){
SchemeRegistry schemeRegistry = new SchemeRegistry();

        // http scheme
        schemeRegistry.register(new Scheme("http", PlainSocketFactory.getSocketFactory(), 80));
        // https scheme
        schemeRegistry.register(new Scheme("https", new EasySSLSocketFactory(), 443));

        params = new BasicHttpParams();
        params.setParameter(ConnManagerPNames.MAX_TOTAL_CONNECTIONS, 1);
        params.setParameter(ConnManagerPNames.MAX_CONNECTIONS_PER_ROUTE, new ConnPerRouteBean(1));
        params.setParameter(HttpProtocolParams.USE_EXPECT_CONTINUE, false);
        HttpProtocolParams.setVersion(params, HttpVersion.HTTP_1_1);
        HttpProtocolParams.setContentCharset(params, "utf8");

        CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
                //set the user credentials for our site "example.com"
        credentialsProvider.setCredentials(new AuthScope("example.com", AuthScope.ANY_PORT),
                new UsernamePasswordCredentials("UserNameHere", "UserPasswordHere"));
        clientConnectionManager = new ThreadSafeClientConnManager(params, schemeRegistry);

        context = new BasicHttpContext();
        context.setAttribute("http.auth.credentials-provider", credentialsProvider);
}






public HttpResponse getResponseFromUrl(String url){
//connection (client has to be created for every new connection)
client = new DefaultHttpClient(clientConnectionManager, params);
HttpGet get = new HttpGet(url);
HttpResponse response = client.execute(get, context);
return response;
}

And that’s it. I hope this will help some of you to solve their problems with self-signed certs!

Tags: android cert certificate https self-signed ssl