LayerCake is a smart contract, layer one consensus bridging application built using theState Connector protocol. LayerCake bridges connect two non-Flare layer one blockchains with transactions being secured by Flare Network. They also connect Flare Network with other smart contract, layer one blockchains to facilitate value transfer back and forth. LayerCake bridges utilize short duration collateral lockups to allow value to transfer between layer one blockchains and protect against reorganization attacks on either chain. LayerCake bridges only facilitate value transfer between an origination chain and one destination chain. This is because each additional destination chain added brings in more complexity and risk to the bridge transactions. For example, LayerCake bridges would facilitate a transfer of ETH from Ethereum to Solana, but not a transfer of Solana issued ETH to the Terra blockchain. LayerCake bridges aim to be as secure and non-custodial as possible.
The two most common implementations of cross-chain bridges today utilize either multi-signature or light client relay schemes to accommodate value transfer between two blockchains. These bridges do not offer the same fundamental safety guarantees as the layer one blockchains that they facilitate value transfer for. Multi-signature bridges essentially custody user funds between a group of counterparties ranging from single to double digits. This bridge construction opens technical and regulatory attack vectors as they are not decentralized and open to social engineering attacks. Light client relay bridges often require a large code base which can make them cumbersome and removes the full richness of properties available through layer one blockchain consensus.
LayerCake bridges also can be a solution to the anti-network effect problem, which theorizes that the more users and value a system has the less useful it becomes due to an increasing risk of hacking. LayerCake aims to solve this problem by utilizing the State Connector protocol, which relays state between connected chains without deteriorating the safety guarantees of those connected chains. The State Connector can validate and propagate state proofs between connected chains while being protected against safety and liveness attacks on the connected chains.
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