First, we show that unfortunately a performance loss is inherent for any protocol that secures against at least 1/3 corruptions in hashpower. Specifically, we formally define a new performance measure called responsiveness, and show that any responsive permissionless consensus protocol cannot tolerate 1/3 or more corruptions in hashpower.
Next, we show a tightly matching uppper bound. Specifically, we propose a new permissionless consensus protocol called hybrid consensus, that is responsive and secures against up to 1/3 corruptions (approximately) in hashpower. Hybrid consensus’s idea is to bootstrap fast permissionless consensus by combining an inefficient blockchain protocol with a fast permissioned consensus protocol. Hybrid consensus uses the blockchain not to agree on transactions, but to agree on rotating committees which in turn execute permissioned consensus protocols to agree on transactions
Chenxing Li, Peilun Li, Dong Zhou, Wei Xu, Fan Long, and Andrew Chi-Chih Yao
Institute for Interdisciplinary Information Sciences, Tsinghua University
Explain liveness attack on PHANTOM
From Deconstructing the Blockchain to Approach Physical Limits,
Conflux’s reference links are not used to determine where to mine blocks or how to confirm them; they are only used to include side-chain blocks into the main chain to improve throughput. The main chain itself is selected by the GHOST rule