TLS over HTTP and Websockets

TLS over HTTP and Websockets

It is also possible to use TLS with the WebSocketConnection, remember to change your protocol from ws to wss. For stricter requirements one can define a custom keystore for their SSL certificates by passing in a modified WebSocketClient to the WebSocketService:

final WebSocketClient webSocketClient = new WebSocketClient(new URI("<WSS-ENDPOINT>"));

final WebSocketService webSocketService =
        new WebSocketService(webSocketClient, false);

// Load the keystore
final KeyStore ks = KeyStore.getInstance(STORETYPE);
final File kf = new File(KEYSTORE_PATH);
ks.load(new FileInputStream(kf), STOREPASSWORD.toCharArray());
final KeyManagerFactory kmf = KeyManagerFactory.getInstance("SunX509");
kmf.init(ks, KEYPASSWORD.toCharArray());
final TrustManagerFactory tmf = TrustManagerFactory.getInstance("SunX509");
tmf.init(ks);

// Create SSL socket
final SSLContext sslContext = SSLContext.getInstance("TLS");
sslContext.init(kmf.getKeyManagers(), tmf.getTrustManagers(), null);
final SSLSocketFactory sslSocketFactory = sslContext.getSocketFactory();

// Use SSL socket in websocket client
webSocketClient.setSocket(sslSocketFactory.createSocket());
webSocketService.connect();

final Web3j web3j = Web3j.build(webSocketService);

Similarly to use TLS over HTTP we will pass modified OkHttpClient client to HttpService:

// Load the Keystore
final KeyStore keyStore = KeyStore.getInstance(KEYSTORE_TYPE);
keyStore.load(new FileInputStream(KEYSTORE_PATH), KEYSTORE_PASSWORD.toCharArray());

final KeyManagerFactory keyManagerFactory = KeyManagerFactory.getInstance("SunX509");
keyManagerFactory.init(keyStore, KEY_PASSWORD.toCharArray());

final TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance("SunX509");
trustManagerFactory.init(keyStore);

final SSLContext sslContext = SSLContext.getInstance("TLS");
sslContext.init(keyManagerFactory.getKeyManagers(), trustManagerFactory.getTrustManagers(), null);

// Create an OkHttpClient with the custom certificate
OkHttpClient client = new OkHttpClient.Builder()
        .sslSocketFactory(sslContext.getSocketFactory(), (X509TrustManager) trustManagerFactory.getTrustManagers()[0])
        .build();

final HttpService httpService = new HttpService("https://<web3j-endpoint>", client, false);
final Web3j web3j = Web3j.build(httpService);

Source: okHttp TLS docs