@bakztfuture seems to be saying they do NOT support bring-your-own-key, but this was 2021, so things might have changed. I don’t see anything official in the docs, and I know some people are doing it, but it might not be the best model long term?
ETA2:
Most “bring-your-own-key” models are opensource software that people would install themselves. I don’t think OpenAI wants you storing keys (even encrypted) for other users… so that’s something to think about too…
ETA3:
Okay… seems it is NOT allowed… I’m not sure if they’re enforcing it, though…