[jedberg]

I've used it for this use case. When I onboard new employees, I add them on Keybase and have them add me, and then I send them their AWS keys via Keybase chat.

I've also used it to exchange AWS keys and other credentials when consulting.

I chose keybase because it was the easiest chat to set up with end-to-end encryption that works on the desktop, where I generally needed to be to copy/paste the keys.

It's certainly not the most secure way to share keys, but it's fairly secure and a decent trade off since I consider the credentials I'm sharing on there to be medium value at most.