Reticulum Treats the Network Underneath It as Replaceable

Reticulum is an interesting attempt to build a networking stack for communications that should keep working even when conventional Internet infrastructure does not.

The part I find most compelling is that Reticulum is not really a LoRa mesh protocol.

It can move across LoRa, packet radio, Ethernet, Wi-Fi, serial connections, TCP, UDP, I2P and custom interfaces. Different transports can be joined into the same network. A Raspberry Pi could, for example, bridge a LoRa segment to Wi-Fi and another packet-radio link while Reticulum handles routing above all of them.

That is a much more interesting abstraction than building another application specifically around one radio.

Reticulum also does not put source addresses into packets. Its normal point-to-point traffic is encrypted, transport nodes only need enough information to move a packet one hop closer to its destination, and no individual router needs to know the entire path.

I would not interpret that as making a transmitter impossible to locate.

The documentation itself acknowledges that observers can still collect metadata such as packet timing and size, and that an IP transport can reveal which addresses are communicating unless something such as I2P is used underneath it.

Radio adds another layer of metadata. Several geographically separated receivers could potentially correlate when and where a transmission was first heard, signal strength and subsequent forwarding activity. Reticulum removes a very useful identifier from the packet, but it cannot repeal radio propagation.

There is another issue I would want to understand before depending on it: maintainability.

The project is actively maintained. Reticulum 1.4.2 was released in July, following several releases this year, including a critical rnsh security update. Its developers describe the API and wire format as stable.

But the criticism about the specification is correct.

There is deliberately no independent protocol specification or RFC. The Python reference implementation and its manual are the authoritative specification, and the project says there never will be a separate formal one.

I don't love that.

Executable specifications are useful, but a network protocol intended to survive infrastructure failures should ideally survive the original implementation and maintainers too. Multiple independently developed implementations working from a precise specification are an excellent way to discover assumptions, ambiguities and bugs.

The project also explicitly warns that Reticulum is relatively young and has not undergone an external security audit.

What about amateur radio?

This is where Reticulum gets awkward in the United States.

FCC Part 97 prohibits amateur stations from transmitting messages encoded for the purpose of obscuring their meaning.

Reticulum, meanwhile, deliberately uses strong encryption for normal communication. Its multi-hop Single destinations are encrypted, while its unencrypted Plain destinations are limited to directly reachable broadcasts and are not transported across multiple hops.

So ordinary private, encrypted Reticulum messaging should not simply be transmitted across U.S. amateur-radio spectrum.

Fortunately, it does not need amateur spectrum.

Reticulum was specifically designed to work over unlicensed communications media. In the U.S., that could mean appropriately configured LoRa hardware in the 915 MHz ISM band, ordinary Wi-Fi spectrum, local Ethernet, private IP networks or the Internet itself.

That actually makes the project more interesting to me.

You could build local LoRa islands, bridge them through whatever Internet connectivity exists, connect buildings over Wi-Fi, add serial radios somewhere else and let the network use whatever paths remain available.

I have not tested Reticulum yet, so I am not ready to call it a solution.

But the concept is good.

Instead of designing the network around one transport, design it so the transport can fail, change or be replaced.

And I can't see the name without thinking about Neal Stephenson's Anathem, one of my favorite books that I have unsuccessfully tried to convince friends to read. Its Reticulum is essentially that world's Internet, eventually overwhelmed by automated systems producing tremendous quantities of convincing garbage.

That particular idea has aged almost uncomfortably well.