When the server is the final recipient of a message sent over TLS, then yes, that is end-to-end encryption (for instance if a load balancer is not decrypting traffic in the middle). If the message's final recipient is a third party, then you are correct, an additional layer of encryption would be necessary. The TEE is the execution environment that needs access to the decrypted data to process the AI operations, therefore it is one end of the end-to-end encryption.

This interpretation basically waters down the meaning of end-to-end encryption to the point of uselessness. You may as well just say "encryption".

E2EE is usually applied in contexts where the message's final recipient is NOT the server on the other end of a TLS connection, so yes, this scenario is a stretch. The point is that in the context of an AI chat app, you have to decide on the boundary that you draw around the server components that are processing the request and necessarily need access to decrypted data, and call that one "end" of the connection.

If Bob and Alice are in an E2EE chat Bob and Alice are the ends. Even if Bob asks Alice a question and she replies back to Bob, Alice is still an end.

Similarly with AI. The AI is one of the ends of the conversation.

So ChatGPT is end-to-end encrypted?

No, because there is a web server that exposes an API that accepts a plaintext prompt and returns plaintext responses (even if this API is exposed via TLS). Since this web server is not the same server as the backend systems that are processing the prompt, it is a middle entity, rather than an end in the system.

The difference here is that the web server receiving a request for Confer receives an encrypted blob that only gets decrypted when running in memory in the TEE where the data will be used, which IS an end in the system.

Is your point that TLS is typically decrypted by a web server rather than directly by the app the web server forwards traffic to?

Yes. I include Cloudflare as part of the infrastructure of the ChatGPT service.

See my other comment, but the answer here is resoundingly "No". For the communication to be end-to-end encrypted the payload needs to be encrypted through all steps of the delivery process until it reached the final entity it is meant for. Infrastructure like cloudflare generally is configured to be able to read the full contents of the web request (TLS interception or Load balancing) and therefore the message lives for a time unencrypted in the memory of a system that is not the intended recipient.

Go read a book on basic cryptography. Please.

I have read through Handbook of Applied Cryptography.