Block-based consensus
Includes proposals of SMR, which can be adapted for blockchain.
Permissionless
(Proposals which include explicit effort for permissionless setting)
Eleftherios Kokoris Kogias, et al. (EPFL)
Use Collective Signing (Schnorr multisignatures + communication trees ) to scale PBFT
Use PoW to create hybrid permissionless BFT
Combine the above with Bitcoin-NG
Vulnerabilities are pointed out in Hybrid Consensus
Untangling Mining Incentives in Bitcoin and ByzCoin Blog by Bryan Ford Rafael Pass Elaine Shi (CornellTech/Cornell, IC3)
Define responsiveness, and show that any responsive permissionless consensus protocol cannot tolerate 1/3 or more corruptions in hashpower.
Hybrid consensus: uses the blockchain (Fruitchain) not to agree on transactions, but to agree on rotating committees which in turn execute permissioned consensus protocols (nrryuya.icon > basically PBFT) to agree on transactions
Mildly adaptive corruption
On-chain stamping mechanism to prevent long range attack
Ittai Abraham, Dahlia Malkhi, Kartik Nayak, Ling Ren, and Alexander Spiegelman
Synchronous, but adopts PBFT for responsiveness
Paxos-style leader election with PoW-based ranks
https://gyazo.com/9357e2c196f55c376bbfe4633540d51f
Permissioned
IBFT
Message size reduction (IBFT 2.x)
Signatures of prepare messages in Round-Change messages are aggregated
Round-Change messages in Pre-Prepare messages are replaced by the hashes (Assume gossip protocol like Tendermint)
Fast path
Based on Best-Case Complexity of Asynchronous Byzantine Consensus
Requirement: all validators are honest and network latency low
Implementation
Guy Golan Gueta (VMware Research) Ittai Abraham (VMware Research) Shelly Grossman (TAU) Dahlia Malkhi (VMware Research) Benny Pinkas (BIU) Michael K. Reiter (UNC-Chapel Hill) Dragos-Adrian Seredinschi (EPFL) Orr Tamir (TAU) Alin Tomescu (MIT)
DSN '19
Linear communication pattern with a collector (a replica selected in a round-robin manner)
BLS signature
Fast-path when all replicas are non-faulty and synchronous
"Reactive" (i.e. responsive)
Locking-based
T-H. Hubert Chan Rafael Pass Elaine Shi
PoC Implementation (Golang) GitHub Assume static corruption but extend to adaptive adversary in A.1
Fundamentally, improvement of Thunderdella (where temporary outage breaks the assumption)
Best-possible partition tolerance
Doubly pipelined-BFT (unlike Hotstuff): With a stable leader, validators vote on a block without notalization
Asynchronous
Andrew Miller (UIUC), Yu Xia (Tsinghua University), Kyle Croman, Elaine Shi (Cornell University), Dawn Song (UC Berkeley)
Atomic broadcast based on asynchronous common subset (ACS, similar to vector consensus in the validity) + erasure codes (Reed-Solomon), threshold encryption
Propose network-level attack on weak/partial synchrony and experiment with PBFT for motivating asynchronous protocol
Malicious network scheduler: Delay messages only if the leader is correct
Aleph Zero Foundation, Jagiellonian University
AFT'19
Improves upon the HoneyBadgerBFT
by reducing the asymptotic latency while matching the optimal communication complexity.
Does not require a trusted dealer thanks to a novel implementation of a trustless ABFT Randomness Beacon
Sisi Duan (UMBC), Michael K. Reiter (UNC Chapel Hill), Haibin Zhang (UMBC)
Family of protocols which improves Honeybadger BFT
Erasure code
No common coin
Bingyong Guo and Zhenliang Lu and Qiang Tang and Jing Xu and Zhenfeng Zhang
CCS'20