TinySSH is a small SSH server using NaCl, TweetNaCl
https://news.ycombinator.com/item?id=39806139
Particularly this comment means that I can use encryption on my servers and whenever I reboot them, I need to just ssh into them. Of course there are some nuances, but still.
tinyssh is great. One use case for it that people may not know about: using it during Linux boot so you can remotely unlock encrypted drives. I have a headless NAS server that uses dm-crypt/LUKS under ZFS. When I update my kernel/ZFS I remotely reboot the server, wait a few seconds, and then ssh into a tinyssh powered encryption key prompt to unlock the drives. (I am immediately booted from ssh, as tinyssh exits.) I can then ssh again a few seconds later and I’m hitting openssh on a fully booted machine that wasn’t able to open the drives without my intervention.