Lightchain

Lightchain is a family of blockchain architectures that emphasizes light clients and scalable verification. In light-chain designs, participants with limited bandwidth and storage can verify the correctness of the global ledger without downloading all blocks.

Origin and scope: The concept draws on ideas from lightweight SPV principles and progression in scalable blockchain research. Various projects have proposed light-chain variants to support mobile devices, IoT, and satellite links.

Architecture and operation: Light-chain networks separate nodes into full nodes that store and produce blocks, and light clients that hold minimal state and request proofs from full nodes. Verification relies on compact proofs of state or block inclusion, often using Merkle trees or validity proofs, along with occasional checkpointing to anchor the chain's history.

Consensus and security: Light-chain designs can be built on top of existing consensus mechanisms, including proof-of-work, practical byzantine fault tolerance, or hybrid schemes. The security guarantees depend on the robustness of the underlying consensus and the availability and honesty of full nodes supplying proofs.

Applications and challenges: Suitable for mobile wallets, sensor networks, and edge devices where full validation is impractical. Challenges include reliance on full nodes for data availability and proof freshness, potential privacy concerns, and the need for trusted verification authorities or firms.