HOPR Cover Traffic App Launches
The moment is almost here: the first cover traffic will soon be live in the HOPR network!
Cover traffic is an essential part of HOPR’s design, essentially arbitrary data which is injected into the network to provide “cover” for the real messages being relayed.
But our new cover traffic app has an important secondary function: distributing staking rewards to node runners in a way that meaningfully benefits the HOPR network.
Cover Traffic App
The first iteration of cover traffic will be an app running on top of HOPR, rather than being directly integrated into nodes at the protocol level. This is a bit different to how we’ve described it before — the ultimate version of cover traffic will indeed be built into nodes, with each node capable of dispersing cover traffic as needed.
So why the shift?
When cover traffic was conceived, HOPR was just launched with a single development team of just three people. Now HOPR has grown to over twenty people, and cover traffic is so important it has its own dev team. Working in parallel like this, it’s far easier to build cover traffic as a separate app then integrate it via the API. It also means it doesn’t need to be coded in Rust, unlike the core protocol.
Second, the cover traffic app has dual roles: in addition to providing privacy, the injected data will be used to disperse HOPR tokens to stakers. Currently node runners are rewarded by airdrop just for being pingable in the network. The cover traffic app will mean that, for the first time, rewards in HOPR will be earned as intended: by relaying data to earn tickets that can be exchanged for HOPR tokens.
Since this budget is allocated by the HOPR Association and will be sent via HOPR Association nodes for the foreseeable future, it makes sense for it to be an app we host and run.
Finally, we expect cover traffic to have all the teething problems you see with any new software. By building the first version of cover traffic as an app, we get more fine-grained control over the service and can gather more useful data. It also lets us change parameters in near-real time if things are off-balance, something which would be impossible if cover traffic was integrated directly into every node.
We also need to gather all kinds of data on topology and latency to try and build a more efficient cover traffic service, and learn about HOPR node functionality in general.
App Design
You can find full details of the cover traffic app on our dedicated wiki. The diagram below shows the various modules which go into making it work.
In brief, HOPR Association will run a number of nodes dedicated to cover traffic. These nodes will gather information about their visible peers on the network, open channels to them, and then distribute packets as 1-hop messages, with the cover traffic node as sender and receiver.
Packets are distributed probabilistically, weighted by stake. The app uses a combination of the data gathered by the nodes and the subgraph data from our payment channel smart contract to decide which nodes to send out packets to at any given time.
A database of eligible nodes and their expected level of cover traffic is maintained and constantly updated. The cover traffic nodes can communicate with each other to share information about latency, availability, and to load balance as needed.
Balancing Incentives and Privacy
The cover traffic app is designed to distribute rewards based on each node’s stake. The full economic model can be found here.
Put cover traffic is fundamentally a privacy feature. So this introduces an interesting interplay between economics and privacy: the nodes which need to be boosted by cover traffic are not necessarily the ones with the highest stake.
In its first version, the cover traffic app will use a naïve strategy based solely on stake and availability. It checks which nodes are available then picks a random 1-hop path weighted by node stake. This will blanket the network with cover traffic, providing additional privacy in a real but rudimentary way.
Once we gather the first data on the reliability of the app, we’ll be able to start crafting more elaborate strategies that can provide targeted privacy while still providing each node with rewards linked to their stake.
This is possible because the cover traffic app has a third function: gathering data about the network and the individual nodes.
Data Gathering
One problem with building a privacy protocol is that it works! That means it’s hard to get info about nodes and the network, because everything is so private. But there’s some exposed data which we can use to analyse the health of the network and the functioning of HOPR nodes individually and as a whole.
We use subgraphs to build a picture of the network topology. Our various smart contracts tell us about the currently open payment channels and how well they’re funded. The cover traffic app and dedicated nodes can also gather data on the network by recording which relays were successful or not. This isn’t the same as seeing data move through the network in real-time but it gives a good approximation!
The cover traffic app also gives us an insight into latency. This will be increasingly important as more use cases join the HOPR ecosystem. Some data transfers need to happen in near real time, while many can tolerate small amounts of latency. Still others actually benefit for large latency, because it can obscure timestamp metadata.
Having information about latency within the network can aid path routing and help provide configurable latency, where different nodes can select their latency tolerance within the network.
All this data gathered by the cover traffic apps will be vital to building the next versions of HOPR, including a future where each node can dynamically provide its own cover traffic.
We will of course provide all this data to node runners when we upgrade our dashboard at https://network.hoprnet.org.
It’s been a long journey to get here, but we’re beyond excited to launch cover traffic and start rewarding node runners for real relaying work!
Sebastian Bürgel,
HOPR Founder
Cover Traffic Wiki: https://github.com/hoprnet/ct-research/wiki
Network: https://network.hoprnet.org
Staking: https://stake.hoprnet.org
Website: https://www.hoprnet.org
Twitter: https://twitter.com/hoprnet
Telegram: https://t.me/hoprnet
Github: https://github.com/hoprnet/
