Yggdrasil Network

The first thing I tried to find on their website and their GitHub was a protocol specification, to be able to implement it independently from the reference implementation. I thought this would be straightforward since it’s advertised as a scheme/protocol, but such a spec isn’t referenced anywhere! Digging on my own I eventually found [1] on a side-branch of one of their other GitHub projects.

Kudos to the author: I think it actually covers a lot of what you’d need to know: crypto identities, message formats, wire protocols, peering and stream semantics, spanning tree updates and root selection, the DHT, forwarding logic, sessions, etc. A couple things are TODOs like how to verify and sign root updates, and there’s some ambiguity in the tiebreaker algorithm for next-hop selection.

It seems to be very tightly coupled to TCP as the transport layer though, since all packets need to be delivered reliably and in the order they were sent, and need to be capable of being fragmented into smaller packets for varying MTU sizes.

[1] https://github.com/yggdrasil-network/yggdrasil-specs/blob/ys...

We did spend a little bit of time documenting the earlier v0.3 protocol, as you have linked, but the protocol has changed significantly in design twice since then. v0.4 changed the DHT quite a bit and v0.5 removed the DHT altogether. As a research project it likely will continue to change until we settle on a design we are happier with, at which point we will definitely spend more time documenting it.

The need for ordered/reliable links is mostly for convenience of development at this stage, but that can be fixed for sure.