Nomad

Nomad is a new design for radically cheaper cross-chain communication without header verification. We expect operating Nomad to cut 90% of gas costs compared to a traditional header relay. To accomplish this, we took inspiration from optimistic systems (a la Optimistic Roll-ups). Nomad features many of the features we prize in an optimistic mechanism, like public verification, low gas fees, broad participation, but has a slightly different security model.

Nomad is a novel approach to blockchain interoperability that leverages an optimistic mechanism to increase the security of cross-chain communication. Using Nomad, developers can securely build cross-chain applications (or xApps) and bridge assets between chains. Nomad channels and the flagship xApp, the Nomad token bridge, are live on Ethereum and Moonbeam, with more chains coming soon.

What we found through connecting the dots backward is that there is a consistent philosophy that informs Nomad’s design. Specifically, there are three core tenets that our decisions anchor to. By leaning on this backbone anytime we encountered a hard decision, we ensured that we developed Nomad in a way that adhered to our values and prioritized delivery over yak shaving.

Nomad will form the base layer of a cross-chain communication network that provides fast, cheap communication for all smart contract chains and rollups. It relies only on widely-available cryptographic primitives (unlike header relays), has a latency of thirty minutes (rather than an ORU’s one week latency), and imposes only about 120,000 gas overhead on message senders.

We thought that these tenets could be useful for other teams working on gnarly problems, and could serve as a guidepost the way it does for us. Without further ado, the three tenets behind Nomad:

Tech matters. Users matter most.

The ability to build solutions to problems that real people experience is what gets us out of bed in the morning. Prioritizing the system can easily distract us from providing great products users want. System design should serve this end; it is not the end itself.

• We value human-facing utility more than interesting primitives.

• If we must choose between applications and mechanisms, we choose applications.

• Our success is measured in the wild, not in the lab.

Complexity is the death of innovation.

We strive to build solutions that are no more complex than they need to be. We avoid new cryptography, and love reusing others’ libraries. Interoperability is inherently complex. Our goal is to make it simple for any developer.

• We value approachable and maintainable code more than minimal code.

• If we must choose between documentation and optimization, we choose documentation.

• Our success is measured in the bazaar, not in the cathedral.

Real harm is more important than theoretical harm.

We strive to take advantage of every tool that protects users. We aim to minimize the probability and impact of security issues. Our security practices are informed by formal analysis, but not centered on it.

• We value the real-world safety of users and funds more than crypto-economic models.

• If we must choose between smart contract security and a new whitepaper, we choose smart contract security.

•Our success is measured in mainnet attacks, not arXiv attacks.

Nomad is an optimistic interoperability protocol that enables secure cross-chain communication.

Using Nomad:

• Users can bridge tokens between chains

• Asset issuers can deploy tokens across chains

• DAOs can facilitate cross-chain governance proposals

• Developers can build native cross-chain applications

The goal of Nomad is to provide the connective tissue to enable users and developers to interact

securely in a multi-chain world.

Nomad enables applications to send data between chains and rollups. Applications interact with

Nomad core contracts to enqueue messages to be sent, after which off-chain agents verify and

ferry these messages between chains.

In order to ensure that message-passing is secure, Nomad uses an optimistic verification

mechanism, inspired by fraud-proof based designs like optimistic rollups. This makes Nomad more

secure, cheaper, and easier to deploy compared to validator / proof-of-stake based interoperability

protocols.