Ask HN: How to ensure privacy while building a chatbot?

I am looking for pointers on how to ensure the privacy of the conversations in the design of a chatbot.

I am developing a chatbot on telegram & whatsapp to assist people in learning language.

I would very much like people to use it, without being used.

1. I want to offer satisfying privacy/encryption for those conversations, and some assurances that this is being honored (hopefully by design).

2. I use OpenAI APIs in the bot, so I need to decrypt these conversations before using the APIs, encrypt them again once the response has been delivered.

Any pointers would be most welcome.