• authenticated data structures
• blockchain
• cross-chain
• light client
• proof-of-stake
• relay

Our proposal extends the CARONTE protocol for authenticated cross-chain data transfer to make it compatible with the Beacon Chain, a novel proof-of-stake blockchain introduced by Ethereum to supersede its previous proof-of-work-based solution. We present a relay architecture that employs an on-chain implementation of a consensus light client to validate Beacon Chain block headers provided by untrusted off-chain third parties. To minimize gas consumption, our solution outsources a portion of the validation process into a zkSNARK circuit. Off-chain relayers are required to execute the circuit and attach the corresponding zero-knowledge proof for each submitted block header.