Java

Upgrade a Plain TCP Connection to TLS

Demonstrates Socket.ConvertToSsl, which upgrades an already-connected plain TCP socket to TLS by performing a client-side TLS handshake over the existing connection.

Background. This supports STARTTLS-style upgrades, where a protocol begins in plaintext and switches to TLS at a defined point. Perform the protocol-specific negotiation first, then call ConvertToSsl.

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Chilkat2 Java

import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.Socket;

public class ChilkatExample {

    public static void main(String[] args) {
        Socket socket = new Socket();

        // Connect as plain TCP (no TLS yet).
        boolean bTls = false;
        int maxWaitMs = 5000;
        try {
            socket.connect("example.com", 5000, bTls, maxWaitMs);

            // At the point where the application protocol permits a STARTTLS-style upgrade, perform any required
            // negotiation, then upgrade the existing connection to TLS with a client-side handshake.
            socket.convertToSsl();
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        System.out.println("Connection upgraded to TLS.");
    }
}