End-to-End Encryption through Kafka

What are some use cases for this?

Looking at the setup code here, this looks a lot like SSL reinvented over Kafka (instead of over TCP), which is not a bad thing, just the mechanism feels a lot like you've automated a tcpdump into the protocol by making the handshake packets persisted in the stream + committed to disks.

This somewhat makes sense if you're going to buy Kafka from a cloud provider without the ability to trust them, but the trust here is not very useful beyond securing transport trust.

E2e for Kafka usually shows up as a mechanism to encrypt each item differently, because that has a bigger use-case in it.

Kafka being an immutable log, there is no way to go back and delete data for a customer who asks for a data deletion or legally mandated GDPR data removals.

Being able to shred the keys is very useful if you have a destination or source attribute based keys - instead of purging data out of the kafka log you can throw away the key.

Perfect Forward Secrecy is pretty standard in TLS handshakes these days, so the persistence of messages should not be an issue.

This pattern of burying TLS inside of application payloads is popping up all over the place. People realize that securing the transport isn't the same as securing the application, which often hops over multiple transports.

Yes it is very well described, as a meditation on architecture. But I still don't see what real world use cases are.

Some examples would be: 1. Alice is the controller of a machine in a factory, Bob is a remote worker controlling the machine from home. (there could be thousands of Alice, one Bob)

2. Alice is an internal system in Enterprise Data Center 1, Bob is a Microsevice in the Cloud

3. Alice is health monitoring device, Bob is a remote doctor's tablet. (there could be 100s of thousands of Alice. On of Bob)

4. Alice is a connected car, Bob is a service in the cloud, that uses a third party vendor's managed Kafka to communicate with Alice and wants to guarantee secure software updates / machine learning model updates to Alice (there is a fleet of Alice).

etc.

Any use case where you're using third party services/intermediaries and want to keep the vulnerability surface of your application as small as possible.