Heterogeneous Narwhal and Paxos

Blockchain interoperability often requires a mutually trusted layer (in the case of roll-ups or side-chains), or a third party (in the case of bridges). Heterogeneous Consensus protocols introduced the possibility for more direct, decentralized interoperability: chains can commit transactions together, given "enough" overlap in their trust assumptions. Like a bridge, such protocols ensure atomicity under specific trust conditions. Unlike a bridge, chains never relinquish control over the safety or liveness of their data.

However, consensus is only part of the story: efficient mempool architectures like Narwhal can dramatically improve scalability and increase chain throughput. However, these mempools also rely on the chain's underlying trust assumptions. We generalize Narwhal for a Heterogeneous Trust model, and explain how to use it with Heterogeneous Paxos to commit cross-chain atomic transactions.