Ech. https://pivot-to-ai.com/2025/08/02/protons-lumo-ai-chatbot-not-end-to-end-encrypted-not-open-source/
Proton says your chats are stored with the same zero-access encryption as your email. That’s great! But their wording is: “end-to-end encryption in your chat history.”
What are the ends in this scenario? And why not just say “end-to-end encryption in your chat”? Well, obviously, because they can’t say that.
If you’re using a remote chatbot like Lumo, the chat has to exist as plain text for the chatbot to see it, for some unspecified length of time. Same if you dump files into the chatbot from your end-to-end-encryptoed Proton Drive — their version of Google Drive.
That’s how most web services work, and it might not sound like a big deal — but Proton’s email famously does not work like that. There is never plain text at rest. So Proton is trying to handwave on their past reputation and say, well, parts of it are totally secure. Just not the rest.
Proton also used to publish complete cryptographic threat models for its products. They didn’t for the AI email assistant and they haven’t for Lumo. It’s a glaring absence.