Kinetex Light Clients are the core component responsible for validating operations in the Kinetex Flash Trade ecosystem, providing states of various blockchains on-chain.
Implemented as smart contracts, these light clients store blockchain historical data, like a linked sequence of block header hashes. Light clients have a primary function to provide the functionality for validation of transactions, storage states, and events on the respective blockchains.
ZK Light Clients
Light clients can be implemented using Zero-Knowledge (ZK) technology. In this approach, the logic for validating block headers is executed off-chain within ZK circuits. This approach significantly reduces gas consumption by handling complex consensus rule checks and validator signature verifications off-chain. Consequently, only a single Zero-Knowledge Proof (ZKP) is generated, offering a cost-effective and efficient on-chain verification process.
Ethereum & Gnosis
Kinetex has ZK light clients for Ethereum and Gnosis networks that are based on top of Succinct Labs light clients. These light clients have been adapted for the requirements of the Flash Trade protocol, ensuring faster block header validation with the ability to access the most recent blocks in a blockchain.
Kinetex actively works on the ZK light client for Bitcoin, which will help to connect the liquidity of the native Bitcoin to all the supported EVM-like networks. This light client is based on top of the BTC-Warp solution and uses Plonky2 proof reduction to Groth16 to achieve much more efficient on-chain verification in terms of gas.
Hashi — EVM Hash Oracle Aggregator
Alternatively, light clients can be implemented using Hashi, an EVM hash oracle aggregator. Hashi aggregates data from different oracle sources, providing a decentralized answer to queries, such as the hash of the last blocks on a specified blockchain. This method is particularly useful for networks without the ability to use ZK, such as Layer-2 networks.
Hashi ensures decentralization by requiring agreement from multiple oracles. If a consensus, for example, of 2/3 or 3/5 oracles, returns the same block hash, it is considered a reliable update for a light client. The ability to receive truly decentralized answers from a set of different oracles can provide a high level of security comparable to ZK-based light clients.
Aggregation of Light Clients
Kinetex has plans to develop its own light clients for networks such as Solana, Tron, Aptos, and others. It is an important and rather lengthy part of the development roadmap, which will allow Kinetex to maximize networks' coverage in the future, ensuring the best interoperability between them and allowing users to use Flash Trade in the most secure and highly gas-efficient manner.
But besides this, Kinetex also involves the aggregation of various ready-made ZK light client solutions, such as:
Combining different solutions will allow Kinetex to validate transactions more efficiently and securely.
Checkpoint-Based Storage Optimization
To enhance the efficiency of smart contract storage, Kinetex Light Clients utilize a checkpoint-based approach. In this implementation, updates are organized as batches of block headers, interconnected and presented in the form of a Merkle Tree. This method allows for the storage of only three essential hashes: first header, last header, and Merkle root, while retaining the capability to validate any transaction within the specified range of blocks. This is achieved by providing a Merkle proof for the corresponding block.
Merkle Mountain Range (MMR)
A more advanced storage optimization technique involves the utilization of Merkle Mountain Ranges (MMRs) as an alternative to traditional Merkle trees. MMRs offer a highly efficient means of accessing historical blockchain data. The append-only nature of MMRs ensures that elements are added from left to right, with parents introduced as soon as two children exist, creating a compact and efficient data structure.
The implementation of MMRs significantly optimizes storage requirements for smart contracts. With MMRs, as few as 10-11 hashes can be stored in the smart contract while providing access to the entire historical blockchain data. This streamlined approach enhances scalability and resource utilization, making it a more efficient solution for smart contract storage in the Kinetex Light Clients ecosystem.
Kinetex Light Clients represent an inclusive and open solution for multi-chain transaction validation. Implemented as on-chain smart contracts, these Light Clients offer a foundational infrastructure for storing blockchain historical data. Importantly, the design is intentionally open and versatile, enabling not only users within the Kinetex ecosystem but also external users and protocols to seamlessly integrate and leverage their capabilities for the efficient building of multi-chain applications.