Android: Trusting SSL certificates
We use a self-signed SSL certificate for the test version of our backend web service. Since our certificate isn't signed by a CA that Android trusts by default, we need to add our server's public certificate to our Android app's trusted store.
These same instructions apply to trusting a custom CA, except you'd get the public certificate directly from the CA instead of from a server.
Required tools:
- OpenSSL's command line client
- Java SE 6 (for keytool)
- Bouncy Castle's provider jar
1. Grab the public certificate from the server you want to trust. Replace ${MY_SERVER} with your server's address.
echo | openssl s_client -connect ${MY_SERVER}:443 2>&1 | \
sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' > mycert.pem
For example, here's the PEM-encoded public certificate from google.com:
-----BEGIN CERTIFICATE----- MIIDITCCAoqgAwIBAgIQL9+89q6RUm0PmqPfQDQ+mjANBgkqhkiG9w0BAQUFADBM MQswCQYDVQQGEwJaQTElMCMGA1UEChMcVGhhd3RlIENvbnN1bHRpbmcgKFB0eSkg THRkLjEWMBQGA1UEAxMNVGhhd3RlIFNHQyBDQTAeFw0wOTEyMTgwMDAwMDBaFw0x MTEyMTgyMzU5NTlaMGgxCzAJBgNVBAYTAlVTMRMwEQYDVQQIEwpDYWxpZm9ybmlh MRYwFAYDVQQHFA1Nb3VudGFpbiBWaWV3MRMwEQYDVQQKFApHb29nbGUgSW5jMRcw FQYDVQQDFA53d3cuZ29vZ2xlLmNvbTCBnzANBgkqhkiG9w0BAQEFAAOBjQAwgYkC gYEA6PmGD5D6htffvXImttdEAoN4c9kCKO+IRTn7EOh8rqk41XXGOOsKFQebg+jN gtXj9xVoRaELGYW84u+E593y17iYwqG7tcFR39SDAqc9BkJb4SLD3muFXxzW2k6L 05vuuWciKh0R73mkszeK9P4Y/bz5RiNQl/Os/CRGK1w7t0UCAwEAAaOB5zCB5DAM BgNVHRMBAf8EAjAAMDYGA1UdHwQvMC0wK6ApoCeGJWh0dHA6Ly9jcmwudGhhd3Rl LmNvbS9UaGF3dGVTR0NDQS5jcmwwKAYDVR0lBCEwHwYIKwYBBQUHAwEGCCsGAQUF BwMCBglghkgBhvhCBAEwcgYIKwYBBQUHAQEEZjBkMCIGCCsGAQUFBzABhhZodHRw Oi8vb2NzcC50aGF3dGUuY29tMD4GCCsGAQUFBzAChjJodHRwOi8vd3d3LnRoYXd0 ZS5jb20vcmVwb3NpdG9yeS9UaGF3dGVfU0dDX0NBLmNydDANBgkqhkiG9w0BAQUF AAOBgQCfQ89bxFApsb/isJr/aiEdLRLDLE5a+RLizrmCUi3nHX4adpaQedEkUjh5 u2ONgJd8IyAPkU0Wueru9G2Jysa9zCRo1kNbzipYvzwY4OA8Ys+WAi0oR1A04Se6 z5nRUP8pJcA2NhUzUnC+MY+f6H/nEQyNv4SgQhqAibAxWEEHXw== -----END CERTIFICATE-----
2. Android has built-in support for the Bouncy Castle keystore format (BKS). Put Bouncy Castle's jar in your classpath, and create a keystore containing only your trusted key.
export CLASSPATH=bcprov-jdk16-145.jar
CERTSTORE=res/raw/mystore.bks
if [ -a $CERTSTORE ]; then
rm $CERTSTORE || exit 1
fi
keytool \
-import \
-v \
-trustcacerts \
-alias 0 \
-file <(openssl x509 -in mycert.pem) \
-keystore $CERTSTORE \
-storetype BKS \
-provider org.bouncycastle.jce.provider.BouncyCastleProvider \
-providerpath /usr/share/java/bcprov.jar \
-storepass ez24get
3. Create a custom Apache HttpClient that uses your custom store for HTTPS connections.
import android.content.Context;
import org.apache.http.conn.ClientConnectionManager;
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.impl.conn.SingleClientConnManager;
import java.io.InputStream;
import java.security.KeyStore;
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));
registry.register(new Scheme("https", newSslSocketFactory(), 443));
return new SingleClientConnManager(getParams(), registry);
}
private SSLSocketFactory newSslSocketFactory() {
try {
KeyStore trusted = KeyStore.getInstance("BKS");
InputStream in = context.getResources().openRawResource(R.raw.mystore);
try {
trusted.load(in, "ez24get".toCharArray());
} finally {
in.close();
}
return new SSLSocketFactory(trusted);
} catch (Exception e) {
throw new AssertionError(e);
}
}
}
That's it! If you think this kind of stuff is fun, Square is hiring.
Friends,
