Yeva Byzek shows the methods available to secure a Kafka Streams application:
To connect to a secured Kafka cluster, Kafka client applications need to provide their security credentials. In the same way, we configure KSQL such that the KSQL servers are authenticated and authorized, and data communication is encrypted when communicating with the Kafka cluster. We can configure KSQL for:
Read the whole thing if you’re thinking about using Kafka Streams.