The paper HotStuff: BFT Consensus in the Lens of Blockchain describes an infinite non-deciding scenario for a theoretical “two-phase” HotStuff variant. Specifically, the authors claim that the addition of a "precursor" voting round ensures that (n-f) participants know of any 'hidden/missing Lock' and a correct leader would be able to propose a value that all honest participants would accept without waiting the maximum network delay (such as Tendermint / Casper FFG).

During this precursor round, if a quorum is achieved and a certificate is created, Replicas will store the highest Precursor (PrepareQC) they know of in a local variable known as HighQC.

The paper details a 'SafeNodePredicate' Replicas use to determine whether or not to accept a Proposal from a Leader.


However, within the SafeNodePredicate the HighQC (highest Precursor) of any Replica is never checked against the proposal. Could a malicious Proposer simply choose to ignore a HighQC removing the safety properties of the Precursor round and forcing a 'Hidden Lock'?


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