Yes it's pretty straightforward. You can even do something much simpler if you want to self-host and just want a sort of encrypted dropbox for yourself.
I recently did a little proof of concept hackathon entry (gopher gala) for a very similar idea which works with keybase.io for keys or your own server - https://sendto.click, which is also open source. This is far simpler of course but there's no reason in principle you couldn't just compile the client yourself, write your own client and use their server, or just write your own client and server, using the same golang crypto libraries, which are here for pgp:
It doesn't have to be quite as complex as the keybase tools, though I'm sure they have reasons for every decision and have thought hard about the way it all works, the crypto libraries they've based it on are open source and relatively straightforward to use.
My one hesitation about using keybase.io would be their business model and whether they'll be around in 5 years. They might have the best intentions but if it doesn't make money, and/or is bought by a large corporation, all bets are off on how the service will evolve or whether it will continue to exist. I'd love to see them start charging money and have a sustainable business model.
I wouldn't be too hesitant to use it. I think it depends mostly on being able to verify everything that they verify. Which they already encourage you to do: leave signed signatures in profiles so that people can verify them independent of keybase.io
I recently did a little proof of concept hackathon entry (gopher gala) for a very similar idea which works with keybase.io for keys or your own server - https://sendto.click, which is also open source. This is far simpler of course but there's no reason in principle you couldn't just compile the client yourself, write your own client and use their server, or just write your own client and server, using the same golang crypto libraries, which are here for pgp:
https://godoc.org/golang.org/x/crypto/openpgp
It doesn't have to be quite as complex as the keybase tools, though I'm sure they have reasons for every decision and have thought hard about the way it all works, the crypto libraries they've based it on are open source and relatively straightforward to use.
My one hesitation about using keybase.io would be their business model and whether they'll be around in 5 years. They might have the best intentions but if it doesn't make money, and/or is bought by a large corporation, all bets are off on how the service will evolve or whether it will continue to exist. I'd love to see them start charging money and have a sustainable business model.