cloud invites are crazy long

[trevj]

Right now, cloud invites include a 2048 bit RSA key:
https://github.com/uProxy/uproxy-docker/blob/master/sshd/issue_invite.sh#L58

Base64-encoded, this causes cloud invites to balloon to >3000 characters!

A 256 bit Ed25519 key would help keep the size of cloud invites to ~500 characters but unfortunately ssh2-streams doesn't support them yet:
mscdex/ssh2-streams#3

[dborkan]

Semi related, Quiver invites are also too long, and also include 2 public keys plus the whole -----BEGIN PGP PUBLIC KEY BLOCK----- and -----END PGP PUBLIC KEY BLOCK----- pieces. Might be good to come up with a similar solution for Quiver and Cloud

[mollyling]

I put in a bug for the --BEGIN/END-- padding. For a minimal invite, the way to do this is figure out a binary format for this and then ascii-encode that. Then a utility function to convert from/to JSON would do it. I doubt the keys can be compressed (e.g., gzip) much, but we could do more with our own format. But maybe that's a long-term issue.

Do we need the full key in there, or just an identifier+hash? Then some way to find the full key. But that's probably just a chicken-egg cycle.

[trevj]

Just noticed this also messes up the www.uproxy.org/invite handler. It gives a 400. That's a blocker for anyone following the upcoming blog post...so raising this to P1.

Perhaps for now we should consider shortening the keys just enough to get us under the 2K URL limit.

[trevj]

Hmm. Right now, Chrome is handling the longer URLs (>3k) just fine. So I don't think this is a blocker after all.