you can api to a url shortener like bitly. the short url can be communicated via a piece of paper. this will create an encrypted messenger operating with full transparency directly from github. 

That's a nice idea. It would go a bit against my requirement that you should be able to communicate the code easily via phone / in person but it's a good idea that has merit.

stacks

bitcoin

Verifiably secure dead drop to share bitcoin addresses and other secrets

I think you could use AES encryption to generate base64 URLs from cleartext. They will be long and ugly, but reversible with a key and not requiring the database.