Android: TLS 1.3 with OkHttp and Conscrypt on all Android versions (Tested on 4.1+)

Android: TLS 1.3 with OkHttp + Conscrypt on all Android versions (Tested on 4.1+)

// Android 4.1+
dependencies {
	implementation 'com.squareup.okhttp3:okhttp:3.12.13'
	implementation 'org.conscrypt:conscrypt-android:2.5.2'
}

// Android 5.0+
dependencies {
	implementation 'com.squareup.okhttp3:okhttp:4.10.0'
	implementation 'org.conscrypt:conscrypt-android:2.5.2'
}

App.java

// Init Conscrypt
Provider conscrypt = Conscrypt.newProvider();

// Add as provider
Security.insertProviderAt(conscrypt, 1);

// Init OkHttp
OkHttpClient.Builder okHttpBuilder = new OkHttpClient()
	.newBuilder()
	.connectionSpecs(Collections.singletonList(ConnectionSpec.RESTRICTED_TLS));

// OkHttp 3.12.x
// ConnectionSpec.COMPATIBLE_TLS = TLS1.0
// ConnectionSpec.MODERN_TLS = TLS1.0 + TLS1.1 + TLS1.2 + TLS 1.3
// ConnectionSpec.RESTRICTED_TLS = TLS 1.2 + TLS 1.3

// OkHttp 3.13+
// ConnectionSpec.COMPATIBLE_TLS = TLS1.0 + TLS1.1 + TLS1.2 + TLS 1.3
// ConnectionSpec.MODERN_TLS = TLS1.2 + TLS 1.3
// ConnectionSpec.RESTRICTED_TLS = TLS 1.2 + TLS 1.3

try {
	X509TrustManager tm = Conscrypt.getDefaultX509TrustManager();
	SSLContext sslContext = SSLContext.getInstance("TLS", conscrypt);
	sslContext.init(null, new TrustManager[] { tm }, null);
	okHttpBuilder.sslSocketFactory(new InternalSSLSocketFactory(sslContext.getSocketFactory()), tm);
} catch (Exception e) {
	e.printStackTrace();
}
  
// Build OkHttp
OkHttpClient okHttpClient = okHttpBuilder.build();

InternalSSLSocketFactory.java

import java.io.IOException;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;
import javax.net.ssl.SSLSocket;
import javax.net.ssl.SSLSocketFactory;

public final class InternalSSLSocketFactory extends SSLSocketFactory {
	private final SSLSocketFactory mSSLSocketFactory;

	public InternalSSLSocketFactory(SSLSocketFactory sslSocketFactory)  {
		this.mSSLSocketFactory = sslSocketFactory;
	}

	@Override
	public String[] getDefaultCipherSuites() {
		return mSSLSocketFactory.getDefaultCipherSuites();
	}

	@Override
	public String[] getSupportedCipherSuites() {
		return mSSLSocketFactory.getSupportedCipherSuites();
	}

	@Override
	public Socket createSocket() throws IOException {
		return enableTLSOnSocket(mSSLSocketFactory.createSocket());
	}

	@Override
	public Socket createSocket(Socket s, String host, int port, boolean autoClose) throws IOException {
		return enableTLSOnSocket(mSSLSocketFactory.createSocket(s, host, port, autoClose));
	}

	@Override
	public Socket createSocket(String host, int port) throws IOException, UnknownHostException {
		return enableTLSOnSocket(mSSLSocketFactory.createSocket(host, port));
	}

	@Override
	public Socket createSocket(String host, int port, InetAddress localHost, int localPort) throws IOException, UnknownHostException {
		return enableTLSOnSocket(mSSLSocketFactory.createSocket(host, port, localHost, localPort));
	}

	@Override
	public Socket createSocket(InetAddress host, int port) throws IOException {
		return enableTLSOnSocket(mSSLSocketFactory.createSocket(host, port));
	}

	@Override
	public Socket createSocket(InetAddress address, int port, InetAddress localAddress, int localPort) throws IOException {
		return enableTLSOnSocket(mSSLSocketFactory.createSocket(address, port, localAddress, localPort));
	}

	private Socket enableTLSOnSocket(Socket socket) {
		//if(socket instanceof SSLSocket) ((SSLSocket) socket).setEnabledProtocols(new String[] {"TLSv1", "TLSv1.1", "TLSv1.2", "TLSv1.3"});
		if(socket instanceof SSLSocket) ((SSLSocket) socket).setEnabledProtocols(new String[] {"TLSv1.2", "TLSv1.3"});
		return socket;
	}
}

Test.java

Request request = new Request.Builder()
	.url("https://tls13.1d.pw") // You can try another TLS 1.3 capable HTTPS server
	.build();

okHttpClient.newCall(request)
	.enqueue(new Callback() {
		@Override
		public void onFailure(final Call call, IOException e) {
			e.printStackTrace();
			Log.d(LOG, "onFailure()");
		}

		@Override
		public void onResponse(Call call,final Response response) throws IOException {
			Log.d(LOG, "onResponse() tlsVersion=" + response.handshake().tlsVersion());
			Log.d(LOG, "onResponse() cipherSuite=" + response.handshake().cipherSuite().toString());
			// D/TestApp##: onResponse() tlsVersion=TLS_1_3
			// D/TestApp##: onResponse() cipherSuite=TLS_AES_256_GCM_SHA384
		}
	});

Can you help to explain the effects of these two classes? Are there any side effects? Thank you!

InternalSSLSocketFactory
InternalX509TrustManager

Fist of all, I updated this gist before my answer.

InternalX509TrustManager: This class handle certificate validation but my implementation was bad, so I replaced it with the default system implementation provided by "Conscrypt.getDefaultX509TrustManager()". A X509TrustManager is required by the "okHttpBuilder.sslSocketFactory" method. With default X509TrustManager no side effect, with my previous implementation maybe too friendly with some bad certificates.

InternalSSLSocketFactory: This class extends "SSLSocketFactory" which is used to create TCP SSL sockets for HTTPS connections. My implementation aims to enable the missing TLS protocols which are not implemented in a device or not activated ("TLSv1", "TLSv1.1", "TLSv1.2", "TLSv1.3"). No side effects with this class.

I use TLS 1.3 in production in Android for more than one year with no issues reported.

Great, thank you!

Hello, after we launched this function, there was a crash in Conscrypt. Have you met it?

google/conscrypt#935

Hi, Can I use this for retrofit library?!

I'm not sure, I don't use retrofit.
But according to the doc, you can pass an okhttpclient to the retrofit builder.
So in theory it should work.

Hello, after we launched this function, there was a crash in Conscrypt. Have you met it?

google/conscrypt#935

In the OkHttp changelog for the v3.12.13:

• Fix: Work around a crash in Android 10 and 11 that may be triggered when two threads concurrently close an SSL socket. This would have appeared in crash logs as NullPointerException: bio == null.

I'm not sure, I don't use retrofit.
But according to the doc, you can pass an okhttpclient to the retrofit builder.
So in theory it should work.

Sorry, Do you know any reference to solve this problem?
I used these scripts that you wrote but threw an exception to me when pass this code to my retrofit builder.
I checked many other scripts to solve this problem but I did not get any answer.

This is my block code that throwing a java.lang.NullPointerException in android 4.4.2 kitkat:
Caused by: java.lang.IllegalStateException: Expected Android API level 21+ but was 19

       Security.insertProviderAt(Conscrypt.newProvider(), 1);
        try {
            OkHttpClient.Builder okHttpBuilder = new OkHttpClient().newBuilder()
                                        .connectionSpecs(Collections.singletonList(ConnectionSpec.MODERN_TLS));
        } catch (ExceptionInInitializerError e) {
            e.printStackTrace();
        }
        try {
            X509TrustManager tm = Conscrypt.getDefaultX509TrustManager();
            SSLContext sslContext = SSLContext.getInstance("TLS", "Conscrypt");
            sslContext.init(null, new TrustManager[] { tm }, null);
            okHttpBuilder.sslSocketFactory(new TLS13SocketFactory(sslContext.getSocketFactory()),
                    tm);
        } catch (Exception e) {
            e.printStackTrace();
        }
        Retrofit retrofitSystem = new Retrofit.Builder()
                    .baseUrl(APIConnector.BASE_URL)
                    .addConverterFactory(GsonConverterFactory.create())
                    .client(okHttpBuilder.build()) // Will be occured an unknown error here.
                    .build();

This is my block code that throwing a java.lang.NullPointerException in android 4.4.2 kitkat:
Caused by: java.lang.IllegalStateException: Expected Android API level 21+ but was 19

       Security.insertProviderAt(Conscrypt.newProvider(), 1);
        try {
            OkHttpClient.Builder okHttpBuilder = new OkHttpClient().newBuilder()
                                        .connectionSpecs(Collections.singletonList(ConnectionSpec.MODERN_TLS));
        } catch (ExceptionInInitializerError e) {
            e.printStackTrace();
        }
        try {
            X509TrustManager tm = Conscrypt.getDefaultX509TrustManager();
            SSLContext sslContext = SSLContext.getInstance("TLS", "Conscrypt");
            sslContext.init(null, new TrustManager[] { tm }, null);
            okHttpBuilder.sslSocketFactory(new TLS13SocketFactory(sslContext.getSocketFactory()),
                    tm);
        } catch (Exception e) {
            e.printStackTrace();
        }
        Retrofit retrofitSystem = new Retrofit.Builder()
                    .baseUrl(APIConnector.BASE_URL)
                    .addConverterFactory(GsonConverterFactory.create())
                    .client(okHttpBuilder.build()) // Will be occured an unknown error here.
                    .build();

OkHttp 3.13+ require Android 5.0+, for Android 4.4 you must use OkHttp 3.12.x (the 3.12.x branch is still updated).
Retrofit 2.70+ require Android 5.0+, for Android 4.4 you must use Retrofit 2.6.4.

Thank you so much, sir!!
I have just a question!
Can I use this method for android API 16+ (Jellybean 4.1+)?

It seems to me that in the past I tested on Android 4.3 and it didn't work, but you can try anyway.

It seems to me that in the past I tested on Android 4.3 and it didn't work, but you can try anyway.

But I tested my application in android 4.2 and it worked well.
I did downgrade the version of the libraries and I think for this reason that worked for me.

This was life savior thanks. Tested on android 4.1 and works like a charm.

como puedo hacerlo reconocible osea si el servidor no es TLSv1.3 que conecte con TLSv1.2. por que en mi caso pongo todos los protocolos y solo me esta funcionando el TLSv1.3 pero quiero que me funcione con todos los protocolos dependiendo de la conexión...

For the SSLContext I had to use the .newProvider() method rather than the string "Conscrypt". Like so:

SSLContext sslContext = SSLContext.getInstance("TLS", Conscrypt.newProvider());

When using just the string I was getting NoSuchProviderException: Conscrypt

Thanks a lot! Works great on Android 4.1.

It doesn't work in my case on my specific API 19 device, but works in emulator