Self-signed SSL acceptance on Android

Question

How do I accept a self-signed certificate in Java on Android?

A code sample would be perfect.

I've looked everywhere on the Internet and while some people claim to have found the solution, it either does not work or there is no sample code to back it up.

Solution 1

I have this functionality in exchangeIt, which connects to Microsoft exchange via WebDav. Here's some code to create an HttpClient which will connect to self signed cert's via SSL:

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

HttpParams params = new BasicHttpParams();
params.setParameter(ConnManagerPNames.MAX_TOTAL_CONNECTIONS, 30);
params.setParameter(ConnManagerPNames.MAX_CONNECTIONS_PER_ROUTE, new ConnPerRouteBean(30));
params.setParameter(HttpProtocolParams.USE_EXPECT_CONTINUE, false);
HttpProtocolParams.setVersion(params, HttpVersion.HTTP_1_1);

ClientConnectionManager cm = new ThreadSafeClientConnManager(params, schemeRegistry);

The EasySSLSocketFactory is here, and the EasyX509TrustManager is here.

The code for exchangeIt is open source, and hosted on googlecode here, if you have any issues. I'm not actively working on it anymore, but the code should work.

Note that since Android 2.2 the process has changed a bit, so check this to make the code above work.

Solution 2

As EJP correctly commented, "Readers should note that this technique is radically insecure. SSL is not secure unless at least one peer is authenticated. See RFC 2246."

Having said that, here's another way, without any extra classes:

import java.security.SecureRandom;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;

import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSession;
import javax.net.ssl.X509TrustManager;

private void trustEveryone() {
    try {
        HttpsURLConnection.setDefaultHostnameVerifier(new HostnameVerifier(){
                public boolean verify(String hostname, SSLSession session) {
                    return true;
                }});
        SSLContext context = SSLContext.getInstance("TLS");
        context.init(null, new X509TrustManager[]{new X509TrustManager(){
            public void checkClientTrusted(X509Certificate[] chain,
                    String authType) throws CertificateException {}
            public void checkServerTrusted(X509Certificate[] chain,
                    String authType) throws CertificateException {}
            public X509Certificate[] getAcceptedIssuers() {
                return new X509Certificate[0];
            }}}, new SecureRandom());
        HttpsURLConnection.setDefaultSSLSocketFactory(
                context.getSocketFactory());
    } catch (Exception e) { // should never happen
        e.printStackTrace();
    }
}

Solution 3

I faced this issue yesterday, while migrating our company's RESTful API to HTTPS, but using self-signed SSL certificates.

I've looking everywhere, but all the "correct" marked answers I've found consisted of disabling certificate validation, clearly overriding all the sense of SSL.

I finally came to a solution:

1. Create Local KeyStore

   To enable your app to validate your self-signed certificates, you need to provide a custom keystore with the certificates in a manner that Android can trust your endpoint.

The format for such custom keystores is "BKS" from BouncyCastle, so you need the 1.46 version of BouncyCastleProvider that you can download here.

You also need your self-signed certificate, I will assume it's named self_cert.pem.

Now the command for creating your keystore is:

<!-- language: lang-sh -->

    $ keytool -import -v -trustcacerts -alias 0 \
    -file *PATH_TO_SELF_CERT.PEM* \
    -keystore *PATH_TO_KEYSTORE* \
    -storetype BKS \
    -provider org.bouncycastle.jce.provider.BouncyCastleProvider \
    -providerpath *PATH_TO_bcprov-jdk15on-146.jar* \
    -storepass *STOREPASS*

PATH_TO_KEYSTORE points to a file where your keystore will be created. It MUST NOT EXIST.

PATH_TO_bcprov-jdk15on-146.jar.JAR is the path to the downloaded .jar libary.

STOREPASS is your newly created keystore password.

2. Include KeyStore in your Application

Copy your newly created keystore from PATH_TO_KEYSTORE to res/raw/certs.bks (certs.bks is just the file name; you can use whatever name you wish)

Create a key in res/values/strings.xml with

<!-- language: lang-xml -->

    <resources>
    ...
        <string name="store_pass">*STOREPASS*</string>
    ...
    </resources>

3. Create a this class that inherits DefaultHttpClient

   import android.content.Context;
   import android.util.Log;
   import org.apache.http.conn.scheme.PlainSocketFactory;
   import org.apache.http.conn.scheme.Scheme;
   import org.apache.http.conn.scheme.SchemeRegistry;
   import org.apache.http.conn.ssl.SSLSocketFactory;
   import org.apache.http.impl.client.DefaultHttpClient;
   import org.apache.http.params.HttpParams;
   
   import java.io.IOException;
   import java.io.InputStream;
   import java.security.*;
   
   public class MyHttpClient extends DefaultHttpClient {
   
       private static Context appContext = null;
       private static HttpParams params = null;
       private static SchemeRegistry schmReg = null;
       private static Scheme httpsScheme = null;
       private static Scheme httpScheme = null;
       private static String TAG = "MyHttpClient";
   
       public MyHttpClient(Context myContext) {
   
           appContext = myContext;
   
           if (httpScheme == null || httpsScheme == null) {
               httpScheme = new Scheme("http", PlainSocketFactory.getSocketFactory(), 80);
               httpsScheme = new Scheme("https", mySSLSocketFactory(), 443);
           }
   
           getConnectionManager().getSchemeRegistry().register(httpScheme);
           getConnectionManager().getSchemeRegistry().register(httpsScheme);
   
       }
   
       private SSLSocketFactory mySSLSocketFactory() {
           SSLSocketFactory ret = null;
           try {
               final KeyStore ks = KeyStore.getInstance("BKS");
   
               final InputStream inputStream = appContext.getResources().openRawResource(R.raw.certs);
   
               ks.load(inputStream, appContext.getString(R.string.store_pass).toCharArray());
               inputStream.close();
   
               ret = new SSLSocketFactory(ks);
           } catch (UnrecoverableKeyException ex) {
               Log.d(TAG, ex.getMessage());
           } catch (KeyStoreException ex) {
               Log.d(TAG, ex.getMessage());
           } catch (KeyManagementException ex) {
               Log.d(TAG, ex.getMessage());
           } catch (NoSuchAlgorithmException ex) {
               Log.d(TAG, ex.getMessage());
           } catch (IOException ex) {
               Log.d(TAG, ex.getMessage());
           } catch (Exception ex) {
               Log.d(TAG, ex.getMessage());
           } finally {
               return ret;
           }
       }
   }
   

Now simply use an instance of **MyHttpClient** as you would with **DefaultHttpClient** to make your HTTPS queries, and it will use and validate correctly your self-signed SSL certificates.

HttpResponse httpResponse;

HttpPost httpQuery = new HttpPost("https://yourserver.com");
... set up your query ...

MyHttpClient myClient = new MyHttpClient(myContext);

try{

    httpResponse = myClient.(peticionHttp);

    // Check for 200 OK code
    if (httpResponse.getStatusLine().getStatusCode() == HttpURLConnection.HTTP_OK) {
        ... do whatever you want with your response ...
    }

}catch (Exception ex){
    Log.d("httpError", ex.getMessage());
}

Solution 4

Unless I missed something, the other answers on this page are DANGEROUS, and are functionally equivalent to not using SSL at all. If you trust self-signed certificates without doing further checks to make sure the certificates are the ones that you are expecting, then anyone can create a self-signed certificate and can pretend to be your server. At that point, you have no real security.

The only legitimate way to do this (without writing a full SSL stack) is to add an additional trusted anchor to be trusted during the certificate verification process. Both involve hard-coding the trusted anchor certificate into your app and adding it to whatever trusted anchors that the OS provides (or else you won't be able to connect to your site if you get a real certificate).

I'm aware of two ways to do this:

1. Create a custom trust store as described at http://www.ibm.com/developerworks/java/library/j-customssl/#8

2. Create a custom instance of X509TrustManager and override the getAcceptedIssuers method to return an array that contains your certificate:

   public X509Certificate[] getAcceptedIssuers()
   {
       X509Certificate[] trustedAnchors =
           super.getAcceptedIssuers();
   
       /* Create a new array with room for an additional trusted certificate. */
       X509Certificate[] myTrustedAnchors = new X509Certificate[trustedAnchors.length + 1];
       System.arraycopy(trustedAnchors, 0, myTrustedAnchors, 0, trustedAnchors.length);  
   
       /* Load your certificate.
   
          Thanks to http://stackoverflow.com/questions/11857417/x509trustmanager-override-without-allowing-all-certs
          for this bit.
        */
       InputStream inStream = new FileInputStream("fileName-of-cert");
       CertificateFactory cf = CertificateFactory.getInstance("X.509");
       X509Certificate cert = (X509Certificate)cf.generateCertificate(inStream);
       inStream.close();
   
       /* Add your anchor cert as the last item in the array. */
       myTrustedAnchors[trustedAnchors.length] = cert;
   
       return myTrustedAnchors;
   }
   

Note that this code is completely untested and may not even compile, but should at least steer you in the right direction.

Solution 5

Brian Yarger's answer works in Android 2.2 as well if you modify the bigger createSocket method overload as follows. It took me a while to get self-signed SSLs working.

public Socket createSocket(Socket socket, String host, int port, boolean autoClose) throws IOException, UnknownHostException {
    return getSSLContext().getSocketFactory().createSocket(socket, host, port, autoClose);
}

View more solutions

Comments

[Faisal Abid]

Where would you call this method?

[Chris Boyle]

You would call it anywhere before opening an https connection. Any connection using URL.openConnection / HttpsURLConnection should be affected.

[Felix]

I can't get this to work. I keep getting IOException: SSL handshake failure: I/O error during system call, Broken pipe on 2.2. Do you happen to know a way around this?

[Nicolas]

I don't like trusting ANY self-signed certificate. Is there a way to add a Certificate Authority so as to prevent Man-in-the-middle attacks?

[sgarman]

I could not get any solution to work, except this. It's a terrible hack but thanks.

[Someone Somewhere]

are the three params.setParameter() required ? The third one will require use of HTTP 1.1

[Abdullah Adam]

can we use this procedure for normal hosting and for facebook applications

[user207421]

Readers should note that this technique is radically insecure. SSL is not secure unless at least one peer is authenticated. See RFC 2246.

[user567879]

A hack without security is bad :)

[Peterdk]

There was some stuff in the news lately about android developers not checking their certificates. So this looks good.

[Peterdk]

Well, turns out X509TrustManager is a interface, so you can't subclass it.

[withoutclass]

Like @NicolasMarchildon stated, this is dangerous since it exposes your application to man in the middle attacks. Here is a good explanation for you on Cert pinning.

[dgatwood]

You can create your own trust manager. publib.boulder.ibm.com/infocenter/javasdk/v6r0/…

[xarlymg89]

I cannot believe that somebody used the same (DefaultHttpClient). I really appreciate your effort, I'm gonna try to adapt it with my Android Project. Thanks!!!

[Frederic Yesid Peña Sánchez]

@CarlosAlbertoMartínezGadea proximamente actualizaré la clase completa, con algunas mejoras. || soon i will update my class with some improvements.

[xarlymg89]

I used a class very similar to yours with some updates. It's the one from stackoverflow.com/questions/4065379/…

[Rafe]

To add to @Peterdk 's first comment: see this paper called "Why Eve and Mallory Love Android: An Analysis of Android SSL (In)Security".

[Admin]

Creating the keystore for secure connections using a program downloaded over an insecure connection misses the point.

[Frederic Yesid Peña Sánchez]

@FredrikPortström I don't get it, i've could downloaded BouncyCastle over an ssh and still being insecure, the point is to guarantee the security between the App<->Server channel...

[Jake]

@FredericYesidPeñaSánchez I am using your code in a project of my mine. I want to know whether the keystore step is to just trust the certificate without validating it ? Are your steps what certificate pinning does ? Also, if you could, please tell how certificate validation can be added to your code ?

[Frederic Yesid Peña Sánchez]

Basically this allows to secure the connection between your server and your device, regardless of your cert being self-signed or issued by trusthworthy CA. I think (may be wrong) you don't neet validating your cert, as you are explicitly asking and expecting YOUR server certificate (the same included in your app)

[Nativ]

@Brian Yarger can you please explain why you registered "http" to port 80? tnx

[Octavian]

It is a bad idea to disable SSL verification.

[Prerak Sola]

The file self_cert.pem, is it the self signed certificate used by the server ? Or I will have to generate a new one for my android app? And if it is generating the new one, how will my server trust it? Are there any parameters that should be same in both the self-signed certificates?

[Frederic Yesid Peña Sánchez]

@PrerakSola yes, it is the server certificate that your app will trust.

[Prerak Sola]

Okay. Thank you very much for the answer.

[portfoliobuilder]

How necessary is this, really? Seems like this is something that should be common practice.

[dgatwood]

Now necessary is what?

[zys]

link

[Rafael Ruiz Muñoz]

What happens when I will need to renew my certificate? will this still work? Thanks

[Frederic Yesid Peña Sánchez]

Well, that implies you also need to update your app to use the new certificate.

[John Calcote]

pointless answer as link is broken