Comment by Charon77
4 months ago
It does if you consider that everyone can act as a relay.
This is also how apple airtags can be find anywhere there's an iphone users nearby.
4 months ago
It does if you consider that everyone can act as a relay.
This is also how apple airtags can be find anywhere there's an iphone users nearby.
> It does if you consider that everyone can act as a relay.
Let's think this through. Imagine civil war breaks out in Australia, and communications infrastructure is destroyed or shut off. I'm in Sydney and want to transmit a message to a friend in Perth.
How exactly is "everyone acts as a relay" going to work? In particular, how is it going to scale when everyone in the country is trying to do the same things?
> This is also how apple airtags can be find anywhere there's an iphone users nearby.
This is incorrect. Airtags (and the Google version) communicate with nearby Internet-connected devices, via Bluetooth and NFC I think. Those nearby Internet-connected devices send the airtag's location to a server.
Nothing about this would work without the Internet.
Yeah, I think current tech assumes a server relay. However imo, and if I were to imagine a solution, in this case I think a message would need a ttl, say 24 hours. In a local mesh/hive everyone would store a copy of the undelivered messages. When people move between hives they would sync these undelivered messages where ttl didn't expire. With perhaps a storage limit of say 1k undelivered messages. Undelivered means a destination user that didn't show in a hive. Wdyt?
> With perhaps a storage limit of say 1k undelivered messages.
If you want this to scale you'd need a scheme to deal with limited cache per device. Something like having each device assign a random priority to each message it has in transit. That way everyone culls a different set when things fill up.
> would need a ttl, say 24 hours
Probably better off scaling priority by age. That way you deliver if at all possible, until it eventually falls out of cache. Some people will be able to dedicate much more storage than others.
I do think this approach would be fairly tractable within "hives" where most of the members have few-hop connections to all of the others, most of the time. The trouble is that there would be so many unpredictable cases:
- Regular travelers between cities (e.g. flight attendants) might be the only reliable links between those hives. Travel patterns change, war breaks out, etc and the hive suddenly splits into two (or more). - A lot of people probably move around too much, and too unpredictable, to participate in a hive that's stable on scales necessary to maintain a TTL of <24h and a reasonable amount of cache for storing others’ undelivered messages.
Maybe I'm being too pessimistic here… I do think it'd be fascinating and instructive to try to build and use a hive/mesh messaging system like this at scale.
The Galapagos Island "post office" is an interesting real world example of serverless/decentralized message delivery: https://www.nationalgeographic.com/travel/article/galapagos-...
Basically, if you visit the Galapagos and you're so inclined… you leave a letter for someone else, and you sift through the letters that have been left there, and try to find one or two that you could conceivably hand-deliver when you return home.
The latency is 100~1000x longer than "normal" snail mail. This is basically with one "hive" constructed around tourists and researchers in an unusual location. But it basically works.
> Airtags (and the Google version) communicate with nearby Internet-connected devices, via Bluetooth and NFC I think
Yes, exactly (BLE, UWB, NFC).
First, Airtags only have a coin-cell battery. It is not remotely viable for them to be doing any sort of serious "communicating" because the battery would die in seconds.
Second, making the Airtag effectively a dumb device means you gain the various security and privacy benefits, and means everything needed to make the magic happen can be transmitted in a single BLE/UWB/NFC packet (bringing us back to the battery life aspect already mentioned).
30,000ft view of how it works: https://support.apple.com/en-gb/guide/security/sece994d0126/...
I haven't studied the protocol but that seems like it has some...obvious routing issues.
Airtags have a totally different architecture than what this protocol is describing, I think.
> I haven't studied the protocol but that seems like it has some...obvious routing issues.
Yes indeed. I don't understand how the peer-to-peer relaying can possibly scale without some directed routing algorithm.
If my phone running Briar is literally handing off every as-yet-undelivered message to every other phone running Briar, we're going to pretty quickly become overwhelmed.
It'll have all the routing issues of a Wi-Fi mesh network, except at a vast scale. https://en.wikipedia.org/wiki/Wireless_ad_hoc_network#Briar