[Y_Y]

Depends what your requirements are. For example, if you don't mind latency and can stay within 100m of the nearest node you can use wifi hosted on phones.

Even without something fancy (e.g WiFi Direct, iptables on a rooted phone) you could have phones alternating between offering a network and promiscuously connecting to offered networks, then routing between these.

It's simple enough that I'd be surprised if nobody has done it, maybe because it's slow and power-hungry? I haven't tested setting up hotspots and switching networks from inside app logic, but afaik it's fine as long as you don't do both at the same time.

edit: Having thought about it for a minute, a DTN over WiFi Direct is probably the way to go. Establishing identity for signing||encryption might be tricky, but if you can arrange that in advance or just yolo it in plain text then should be straightforward. Can't find any prior art though. I'll let Codex have a go and report back.