[Olsr-users] PKI architecture for freifunk/funkfeier

[Juliusz Chroboczek]

> Theoretically we could just set up a central PKI (which would make things
> very easy), but this would allow the owner/maintainer of the PKI to
> control the whole network. This is not acceptable for a community project
> like Freifunk and Funkfeuer.

Yep.  Additionally, as others have mentioned, you don't want to perform
asymmetric crypto on every routing packet.

> My idea is that each gateway to the internet set up it's own PKI root
> key. The owners of the gateways can build something like a web of trust
> between each other.

A simpler solution would be for each node to have a list of trusted keys
(stored as a file somewhere in the filesystem).  Your node would
periodically (say, once every night) download a PGP-signed list of trusted
keys.

Friendly people could then provide lists of public keys of trusted
gateways.  For example, I could program my node to download the list
provided by Henning and the list provided by Aaron, merge the two, then
remove key 77FF5F3B, which happens to belong to somebody I don't trust.

The main advantage is that all of the complex policy issues are cleanly
encapsulated in the downloading process -- the routing daemon only checks
the packets against a list of keys.  The main flaw is that it means that
a new gateway cannot fully join the network in less than 24 hours.

I'm sure there are hashing schemes that are cheap enough for your average
200MHz MIPS chip.

                                        Juliusz