[android] accepting HTTPS connections with self-signed certificates

I'm trying to make HTTPS connections, using HttpClient lib, but the problem is that, since the certificate isn't signed by a recognized Certificate Authority (CA) like Verisign,GlobalSIgn, etc., listed on the set of Android Trusted Certificates, I keep getting javax.net.ssl.SSLException: Not trusted server certificate.

I've seen solutions where you simply accept all certificates, but what if I want to ask the user?

I want to get a dialog similar to that of the browser, letting the user decide to continue or not. Preferably I'd like to use the same certificatestore as the browser. Any ideas?

The top answer didn´t work for me. After some investigation I found the required information on "Android Developer": https://developer.android.com/training/articles/security-ssl.html#SelfSigned

Creating an empty implementation of X509TrustManager did the trick:

private static class MyTrustManager implements X509TrustManager
{

    @Override
    public void checkClientTrusted(X509Certificate[] chain, String authType)
         throws CertificateException
    {
    }

    @Override
    public void checkServerTrusted(X509Certificate[] chain, String authType)
        throws CertificateException
    {
    }

    @Override
    public X509Certificate[] getAcceptedIssuers()
    {
        return null;
    }

}

...

HttpsURLConnection conn = (HttpsURLConnection) url.openConnection();
try
{
    // Create an SSLContext that uses our TrustManager
    SSLContext context = SSLContext.getInstance("TLS");
    TrustManager[] tmlist = {new MyTrustManager()};
    context.init(null, tmlist, null);
    conn.setSSLSocketFactory(context.getSocketFactory());
}
catch (NoSuchAlgorithmException e)
{
    throw new IOException(e);
} catch (KeyManagementException e)
{
    throw new IOException(e);
}
conn.setRequestMethod("GET");
int rcode = conn.getResponseCode();

Please be aware that this empty implementation of TustManager is just an example and using it in a productive environment would cause a severe security threat!

If you have a custom/self-signed certificate on server that is not there on device, you can use the below class to load it and use it on client side in Android:

Place the certificate *.crt file in /res/raw so that it is available from R.raw.*

Use below class to obtain an HTTPClient or HttpsURLConnection which will have a socket factory using that certificate :

package com.example.customssl;

import android.content.Context;
import org.apache.http.client.HttpClient;
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.AllowAllHostnameVerifier;
import org.apache.http.conn.ssl.SSLSocketFactory;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpParams;

import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManagerFactory;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.cert.Certificate;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;

public class CustomCAHttpsProvider {

    /**
     * Creates a {@link org.apache.http.client.HttpClient} which is configured to work with a custom authority
     * certificate.
     *
     * @param context       Application Context
     * @param certRawResId  R.raw.id of certificate file (*.crt). Should be stored in /res/raw.
     * @param allowAllHosts If true then client will not check server against host names of certificate.
     * @return Http Client.
     * @throws Exception If there is an error initializing the client.
     */
    public static HttpClient getHttpClient(Context context, int certRawResId, boolean allowAllHosts) throws Exception {


        // build key store with ca certificate
        KeyStore keyStore = buildKeyStore(context, certRawResId);

        // init ssl socket factory with key store
        SSLSocketFactory sslSocketFactory = new SSLSocketFactory(keyStore);

        // skip hostname security check if specified
        if (allowAllHosts) {
            sslSocketFactory.setHostnameVerifier(new AllowAllHostnameVerifier());
        }

        // basic http params for client
        HttpParams params = new BasicHttpParams();

        // normal scheme registry with our ssl socket factory for "https"
        SchemeRegistry schemeRegistry = new SchemeRegistry();
        schemeRegistry.register(new Scheme("http", PlainSocketFactory.getSocketFactory(), 80));
        schemeRegistry.register(new Scheme("https", sslSocketFactory, 443));

        // create connection manager
        ThreadSafeClientConnManager cm = new ThreadSafeClientConnManager(params, schemeRegistry);

        // create http client
        return new DefaultHttpClient(cm, params);
    }

    /**
     * Creates a {@link javax.net.ssl.HttpsURLConnection} which is configured to work with a custom authority
     * certificate.
     *
     * @param urlString     remote url string.
     * @param context       Application Context
     * @param certRawResId  R.raw.id of certificate file (*.crt). Should be stored in /res/raw.
     * @param allowAllHosts If true then client will not check server against host names of certificate.
     * @return Http url connection.
     * @throws Exception If there is an error initializing the connection.
     */
    public static HttpsURLConnection getHttpsUrlConnection(String urlString, Context context, int certRawResId,
                                                           boolean allowAllHosts) throws Exception {

        // build key store with ca certificate
        KeyStore keyStore = buildKeyStore(context, certRawResId);

        // Create a TrustManager that trusts the CAs in our KeyStore
        String tmfAlgorithm = TrustManagerFactory.getDefaultAlgorithm();
        TrustManagerFactory tmf = TrustManagerFactory.getInstance(tmfAlgorithm);
        tmf.init(keyStore);

        // Create an SSLContext that uses our TrustManager
        SSLContext sslContext = SSLContext.getInstance("TLS");
        sslContext.init(null, tmf.getTrustManagers(), null);

        // Create a connection from url
        URL url = new URL(urlString);
        HttpsURLConnection urlConnection = (HttpsURLConnection) url.openConnection();
        urlConnection.setSSLSocketFactory(sslContext.getSocketFactory());

        // skip hostname security check if specified
        if (allowAllHosts) {
            urlConnection.setHostnameVerifier(new AllowAllHostnameVerifier());
        }

        return urlConnection;
    }

    private static KeyStore buildKeyStore(Context context, int certRawResId) throws KeyStoreException, CertificateException, NoSuchAlgorithmException, IOException {
        // init a default key store
        String keyStoreType = KeyStore.getDefaultType();
        KeyStore keyStore = KeyStore.getInstance(keyStoreType);
        keyStore.load(null, null);

        // read and add certificate authority
        Certificate cert = readCert(context, certRawResId);
        keyStore.setCertificateEntry("ca", cert);

        return keyStore;
    }

    private static Certificate readCert(Context context, int certResourceId) throws CertificateException, IOException {

        // read certificate resource
        InputStream caInput = context.getResources().openRawResource(certResourceId);

        Certificate ca;
        try {
            // generate a certificate
            CertificateFactory cf = CertificateFactory.getInstance("X.509");
            ca = cf.generateCertificate(caInput);
        } finally {
            caInput.close();
        }

        return ca;
    }

}

Key points:

1. Certificate objects are generated from .crt files.
2. A default KeyStore is created.
3. keyStore.setCertificateEntry("ca", cert) is adding certificate to key store under alias "ca". You modify the code to add more certificates (intermediate CA etc).
4. Main objective is to generate a SSLSocketFactory which can then be used by HTTPClient or HttpsURLConnection.
5. SSLSocketFactory can be configured further, for example to skip host name verification etc.

More information at : http://developer.android.com/training/articles/security-ssl.html

I was frustrated trying to connect my Android App to my RESTful service using https. Also I was a bit annoyed about all the answers that suggested to disable certificate checking altogether. If you do so, whats the point of https?

After googled about the topic for a while, I finally found this solution where external jars are not needed, just Android APIs. Thanks to Andrew Smith, who posted it on July, 2014

 /**
 * Set up a connection to myservice.domain using HTTPS. An entire function
 * is needed to do this because myservice.domain has a self-signed certificate.
 * 
 * The caller of the function would do something like:
 * HttpsURLConnection urlConnection = setUpHttpsConnection("https://littlesvr.ca");
 * InputStream in = urlConnection.getInputStream();
 * And read from that "in" as usual in Java
 * 
 * Based on code from:
 * https://developer.android.com/training/articles/security-ssl.html#SelfSigned
 */
public static HttpsURLConnection setUpHttpsConnection(String urlString)
{
    try
    {
        // Load CAs from an InputStream
        // (could be from a resource or ByteArrayInputStream or ...)
        CertificateFactory cf = CertificateFactory.getInstance("X.509");

        // My CRT file that I put in the assets folder
        // I got this file by following these steps:
        // * Go to https://littlesvr.ca using Firefox
        // * Click the padlock/More/Security/View Certificate/Details/Export
        // * Saved the file as littlesvr.crt (type X.509 Certificate (PEM))
        // The MainActivity.context is declared as:
        // public static Context context;
        // And initialized in MainActivity.onCreate() as:
        // MainActivity.context = getApplicationContext();
        InputStream caInput = new BufferedInputStream(MainActivity.context.getAssets().open("littlesvr.crt"));
        Certificate ca = cf.generateCertificate(caInput);
        System.out.println("ca=" + ((X509Certificate) ca).getSubjectDN());

        // Create a KeyStore containing our trusted CAs
        String keyStoreType = KeyStore.getDefaultType();
        KeyStore keyStore = KeyStore.getInstance(keyStoreType);
        keyStore.load(null, null);
        keyStore.setCertificateEntry("ca", ca);

        // Create a TrustManager that trusts the CAs in our KeyStore
        String tmfAlgorithm = TrustManagerFactory.getDefaultAlgorithm();
        TrustManagerFactory tmf = TrustManagerFactory.getInstance(tmfAlgorithm);
        tmf.init(keyStore);

        // Create an SSLContext that uses our TrustManager
        SSLContext context = SSLContext.getInstance("TLS");
        context.init(null, tmf.getTrustManagers(), null);

        // Tell the URLConnection to use a SocketFactory from our SSLContext
        URL url = new URL(urlString);
        HttpsURLConnection urlConnection = (HttpsURLConnection)url.openConnection();
        urlConnection.setSSLSocketFactory(context.getSocketFactory());

        return urlConnection;
    }
    catch (Exception ex)
    {
        Log.e(TAG, "Failed to establish SSL connection to server: " + ex.toString());
        return null;
    }
}

It worked nice for my mockup App.

I wrote small library ssl-utils-android to trust particular certificate on Android.

You can simply load any certificate by giving the filename from assets directory.

Usage:

OkHttpClient client = new OkHttpClient();
SSLContext sslContext = SslUtils.getSslContextForCertificateFile(context, "BPClass2RootCA-sha2.cer");
client.setSslSocketFactory(sslContext.getSocketFactory());

Here's how you can add additional certificates to your KeyStore to avoid this problem: Trusting all certificates using HttpClient over HTTPS

It won't prompt the user like you ask, but it will make it less likely that the user will run into a "Not trusted server certificate" error.

The following main steps are required to achieve a secured connection from Certification Authorities which are not considered as trusted by the android platform.

As requested by many users, I've mirrored the most important parts from my blog article here:

1. Grab all required certificates (root and any intermediate CA’s)
2. Create a keystore with keytool and the BouncyCastle provider and import the certs
3. Load the keystore in your android app and use it for the secured connections (I recommend to use the Apache HttpClient instead of the standard java.net.ssl.HttpsURLConnection (easier to understand, more performant)

Grab the certs

You have to obtain all certificates that build a chain from the endpoint certificate the whole way up to the Root CA. This means, any (if present) Intermediate CA certs and also the Root CA cert. You don’t need to obtain the endpoint certificate.

Create the keystore

Download the BouncyCastle Provider and store it to a known location. Also ensure that you can invoke the keytool command (usually located under the bin folder of your JRE installation).

Now import the obtained certs (don’t import the endpoint cert) into a BouncyCastle formatted keystore.

I didn’t test it, but I think the order of importing the certificates is important. This means, import the lowermost Intermediate CA certificate first and then all the way up to the Root CA certificate.

With the following command a new keystore (if not already present) with the password mysecret will be created and the Intermediate CA certificate will be imported. I also defined the BouncyCastle provider, where it can be found on my file system and the keystore format. Execute this command for each certificate in the chain.

keytool -importcert -v -trustcacerts -file "path_to_cert/interm_ca.cer" -alias IntermediateCA -keystore "res/raw/mykeystore.bks" -provider org.bouncycastle.jce.provider.BouncyCastleProvider -providerpath "path_to_bouncycastle/bcprov-jdk16-145.jar" -storetype BKS -storepass mysecret

Verify if the certificates were imported correctly into the keystore:

keytool -list -keystore "res/raw/mykeystore.bks" -provider org.bouncycastle.jce.provider.BouncyCastleProvider -providerpath "path_to_bouncycastle/bcprov-jdk16-145.jar" -storetype BKS -storepass mysecret

Should output the whole chain:

RootCA, 22.10.2010, trustedCertEntry, Thumbprint (MD5): 24:77:D9:A8:91:D1:3B:FA:88:2D:C2:FF:F8:CD:33:93
IntermediateCA, 22.10.2010, trustedCertEntry, Thumbprint (MD5): 98:0F:C3:F8:39:F7:D8:05:07:02:0D:E3:14:5B:29:43

Now you can copy the keystore as a raw resource in your android app under res/raw/

Use the keystore in your app

First of all we have to create a custom Apache HttpClient that uses our keystore for HTTPS connections:

import org.apache.http.*

public class MyHttpClient extends DefaultHttpClient {

    final Context context;

    public MyHttpClient(Context context) {
        this.context = context;
    }

    @Override
    protected ClientConnectionManager createClientConnectionManager() {
        SchemeRegistry registry = new SchemeRegistry();
        registry.register(new Scheme("http", PlainSocketFactory.getSocketFactory(), 80));
        // Register for port 443 our SSLSocketFactory with our keystore
        // to the ConnectionManager
        registry.register(new Scheme("https", newSslSocketFactory(), 443));
        return new SingleClientConnManager(getParams(), registry);
    }

    private SSLSocketFactory newSslSocketFactory() {
        try {
            // Get an instance of the Bouncy Castle KeyStore format
            KeyStore trusted = KeyStore.getInstance("BKS");
            // Get the raw resource, which contains the keystore with
            // your trusted certificates (root and any intermediate certs)
            InputStream in = context.getResources().openRawResource(R.raw.mykeystore);
            try {
                // Initialize the keystore with the provided trusted certificates
                // Also provide the password of the keystore
                trusted.load(in, "mysecret".toCharArray());
            } finally {
                in.close();
            }
            // Pass the keystore to the SSLSocketFactory. The factory is responsible
            // for the verification of the server certificate.
            SSLSocketFactory sf = new SSLSocketFactory(trusted);
            // Hostname verification from certificate
            // http://hc.apache.org/httpcomponents-client-ga/tutorial/html/connmgmt.html#d4e506
            sf.setHostnameVerifier(SSLSocketFactory.STRICT_HOSTNAME_VERIFIER);
            return sf;
        } catch (Exception e) {
            throw new AssertionError(e);
        }
    }
}

We have created our custom HttpClient, now we can use it for secure connections. For example when we make a GET call to a REST resource:

// Instantiate the custom HttpClient
DefaultHttpClient client = new MyHttpClient(getApplicationContext());
HttpGet get = new HttpGet("https://www.mydomain.ch/rest/contacts/23");
// Execute the GET call and obtain the response
HttpResponse getResponse = client.execute(get);
HttpEntity responseEntity = getResponse.getEntity();

That's it ;)

None of these fixes worked for my develop platform targeting SDK 16, Release 4.1.2, so I found a workaround.

My app stores data on server using "http://www.example.com/page.php?data=somedata"

Recently page.php was moved to "https://www.secure-example.com/page.php" and I keep getting "javax.net.ssl.SSLException: Not trusted server certificate".

Instead of accepting all certificates for only a single page, starting with this guide I solved my problem writing my own page.php published on "http://www.example.com/page.php"

<?php

caronte ("https://www.secure-example.com/page.php");

function caronte($url) {
    // build curl request
    $ch = curl_init();
    foreach ($_POST as $a => $b) {
        $post[htmlentities($a)]=htmlentities($b);
    }
    curl_setopt($ch, CURLOPT_URL,$url);
    curl_setopt($ch, CURLOPT_POST, 1);
    curl_setopt($ch, CURLOPT_POSTFIELDS,http_build_query($post));

    // receive server response ...
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    $server_output = curl_exec ($ch);
    curl_close ($ch);

    echo $server_output;
}

?>

Google recommends the usage of Android Volley for HTTP/HTTPS connections, since that HttpClient is deprecated. So, you know the right choice :).

And also, NEVER NUKE SSL Certificates (NEVER!!!).

To nuke SSL Certificates, is totally against the purpose of SSL, which is promoting security. There's no sense of using SSL, if you're planning to bomb all SSL certificates that comes. A better solution would be creating a custom TrustManager on your App + using Android Volley for HTTP/HTTPS connections.

Here's a Gist which I created, with a basic LoginApp, performing HTTPS connections, using a Self-Signed Certificate on the server-side, accepted on the App.

Here's also another Gist that may help, for creating Self-Signed SSL Certificates for setting up on your Server and also using the certificate on your App. Very important: you must copy the .crt file which was generated by the script above, to the "raw" directory from your Android project.

Jan 19th, 2020 Self Signed Certificate ISSUE FIX:

To play video , image , calling webservice for any self signed certificate or connecting to any unsecured url just call this method before performing any action , it will fix your issue regarding certificate issue :

KOTLIN CODE

  private fun disableSSLCertificateChecking() {
        val hostnameVerifier = object: HostnameVerifier {
            override fun verify(s:String, sslSession: SSLSession):Boolean {
                return true
            }
        }
        val trustAllCerts = arrayOf<TrustManager>(object: X509TrustManager {
            override fun getAcceptedIssuers(): Array<X509Certificate> {
                TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
            }

            //val acceptedIssuers:Array<X509Certificate> = null
            @Throws(CertificateException::class)
            override fun checkClientTrusted(arg0:Array<X509Certificate>, arg1:String) {// Not implemented
            }
            @Throws(CertificateException::class)
            override fun checkServerTrusted(arg0:Array<X509Certificate>, arg1:String) {// Not implemented
            }
        })
        try
        {
            val sc = SSLContext.getInstance("TLS")
            sc.init(null, trustAllCerts, java.security.SecureRandom())
            HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory())
            HttpsURLConnection.setDefaultHostnameVerifier(hostnameVerifier)
        }
        catch (e: KeyManagementException) {
            e.printStackTrace()
        }
        catch (e: NoSuchAlgorithmException) {
            e.printStackTrace()
        }
    }

Maybe this will helpful... it works on java clients using self-signed certificates (there is no check of the certificate). Be careful and use it only for development cases because that is no secure at all!!

How to ignore SSL certificate errors in Apache HttpClient 4.0

Hope it will works on Android just adding HttpClient library... good luck!!

This is problem resulting from lack of SNI(Server Name Identification) support inA,ndroid 2.x. I was struggling with this problem for a week until I came across the following question, which not only gives a good background of the problem but also provides a working and effective solution devoid of any security holes.

'No peer certificate' error in Android 2.3 but NOT in 4

Simplest way for create SSL certificate

Open Firefox (I suppose it's also possible with Chrome, but it's easier for me with FF)

Visit your development site with a self-signed SSL certificate.

Click on the certificate (next to the site name)

Click on "More information"

Click on "View certificate"

Click on "Details"

Click on "Export..."

Choose "X.509 Certificate whith chain (PEM)", select the folder and name to save it and click "Save"

Go to command line, to the directory where you downloaded the pem file and execute "openssl x509 -inform PEM -outform DM -in .pem -out .crt"

Copy the .crt file to the root of the /sdcard folder inside your Android device Inside your Android device, Settings > Security > Install from storage.

It should detect the certificate and let you add it to the device Browse to your development site.

The first time it should ask you to confirm the security exception. That's all.

The certificate should work with any browser installed on your Android (Browser, Chrome, Opera, Dolphin...)

Remember that if you're serving your static files from a different domain (we all are page speed bitches) you also need to add the certificate for that domain.