Chain Relay/Light client
Nakamoto PoW
Background: synchronous consensus cannot verify finality only by computation deterministically
Synchrony assumption requires the program (i.e. verifier) to gain sufficient information (e.g. chains)
Solution: probabilistic verification of (probabilistic) finality
Summa
Interlay (XCLAIM)
Optimistically accept block headers, and disputers are responsible for detecting and disputing submitted illegal block headers.
NiPoPoW
Aggelos Kiayias, Andrew Miller, and Dionysis Zindros
Every block has pointers to the previous superblock of each level
Can be introduced by velvet fork
nrryuya.icon > infix proofs
Sub-linear (logarithmic in the size of the chain) complexity
Proofs in backbone & random oracle model
Assumption: No eclipse attack
Stelios Daveas and Kostis Karantias and Aggelos Kiayias and Dionysis Zindros
AFT'20
Thesis of Kostis Karantias
Benedikt B¨unz, Lucianna Kiffer, Loi Luu, and Mahdi Zamani
S&P'20, Scaling Bitcoin'19 Slide "How does the MMR data structure differ from the interlink pointers proposed in NiPoPoW?" Tweet Sub-linear (logarithmic in the size of the chain) complexity
Applicable for any Nakamoto consensus
Kaihua Qin, Henryk Hadass, Arthur Gervais, Joel Reardon
ZKP
Martin Westerkamp and Jacob Eberhardt (TU Berlin)
IEEE S&B'20
zk-SNARK-based ChainRelay from Bitcoin to Ethereum
The Relay cost is constant for any batch size
ZoKrates
Difficulty target is encoded within the block header in Proof-of-Work blockchains. The offchain-program extracts the target value and utilizes it during the validation process.
To prevent attackers from submitting block headers that encode invalid target values which cannot be detected within the off-chain computation, the relay contract verifies its correctness before accepting a proof
zkSNARKs for Bitcoin transaction inclusion proofs on Ethereum via ZoKrates
Transaction inclusion proof
Alexei Zamyatin, Zeta Avarikioti, Daniel Perez, and William J. Knottenbel
Other than Bitcoin
PeaceRelay
Similar to BTCRelay, for ETH <-> ETC
Efficient verification of Ethash
A BTC Relay-inspired Zcash SPV client on the EVM
Others
FC'20
Kostis Karantias, Aggelos Kiayias, and Dionysis Zindros
Peter Robinson (ConsenSys, University of Queensland) John Brainard (ConsenSys)
Pinning (i.e. relay) for private sidechain
Keep the participants anonymous by optimistically trust Quiet Guardian
No anonymity in the dispute process
Talk by Max Grabner Video Mediums