A quick problem that came up yesterday... Proof of unique validator Motivation: we want a sybil-resistant P2P network. This is about to become more important due to data availability sampling. We particarly want to ensure that validators get assured access to DAS to prevent attackers from compromising liveness. So, one family of solutions involves validator nodes giving each other priority at the P2P. Many specific solutions--S/Kademlia, maybe special GossipSub groups for validators, or just reserving at least m out of n slots in the routing table for validators. In each case, we get the following problem:

One of my goals this year was to understand blockchains in depth. In this guest post, I'll take you with me on part of that journey. We'll explore two related prototypes for interoperability between Bitcoin and Ethereum. The first is a cross-chain light client, while the second is a cross-chain decentralized exchange. Bitcoin Mirror Bitcoin Mirror is a bitcoin light client that runs on the EVM. Here's the testnet BtcMirror contract. The mechanism is straightforward: anyone can submit a list of Bitcoin block headers. The contract checks header validity, keeping only the heaviest chain it has seen. (In other words, each time you submit, you can either extend the current chain or reorg--but either way, you must set a new high score for the chain with the most work, replacing what was there before.) As long as one honest actor is running a submitter script, and as long as the majority of bitcoin hashpower remains honest, the contract tracks the canonical chain. This lets users prove Bitcoin payments on Ethereum, opening some interesting possibilities. For example,