Not really. A DHTs can perform this without a centralized discovery service. Bit torrent for instance uses this, and clients can trade peers without being on the DHT.
Additionally there's so many bittorrent clients that there's millions of machines in the DHT and even a brute force search of IPv4 is't going to take long to find one of the millions, which will happily give you dozens of other peers.
So sure many clients include a bootstrap server for the DHT, but that's needed once and you can skip that if you are willing scan a few 1000 hosts for a client.
I've pondered writing a DHT based client for signal like functionality (sync messages, async messages, and resistance to traffic analysis), I don't see any technical blockers. I get why signal is centralized and does have some attractive features that would be hard to match with a p2p setup. In particular quick startups, low message latency, and battery/network efficiency. With that said I think a p2p e2e chat client is quite feasible.
What would make it MUCH more feasible is people started buying wallwart arm systems (more common years ago), or raspberry Pis and ran a p2p client as a service so that clients in the home could leverage the service for email, chat, file transfers, etc.
None are current AFAIK. I do think that the downsides of P2P could be largely offset by assuming a raspberry Pi or equivalent small system to offset the battery, bandwidth, and CPU penalties that are so hard to justify on Mobile.
So they are of historical interest only, but if you want to did up the history I'll give you some search terms. Marvell had a $99 reference platform called the SheevaPlug CloudEngine had a Pogoplug, CTera had a CloudPLug, Seagate DockStar, GuruPlug, DreamPlug, PylonPlug, sipJack, GeNiJack, etc. etc. etc.
They all had a GHz or so CPU, GigE, 512MB ram, etc.
Additionally there's so many bittorrent clients that there's millions of machines in the DHT and even a brute force search of IPv4 is't going to take long to find one of the millions, which will happily give you dozens of other peers.
So sure many clients include a bootstrap server for the DHT, but that's needed once and you can skip that if you are willing scan a few 1000 hosts for a client.
I've pondered writing a DHT based client for signal like functionality (sync messages, async messages, and resistance to traffic analysis), I don't see any technical blockers. I get why signal is centralized and does have some attractive features that would be hard to match with a p2p setup. In particular quick startups, low message latency, and battery/network efficiency. With that said I think a p2p e2e chat client is quite feasible.
What would make it MUCH more feasible is people started buying wallwart arm systems (more common years ago), or raspberry Pis and ran a p2p client as a service so that clients in the home could leverage the service for email, chat, file transfers, etc.