Weak Subjectivity
consensus · proof-of-stake
A proof-of-stake property where new or long-offline nodes need a recent trusted checkpoint to sync safely.
Weak subjectivity means a proof-of-stake node cannot always determine the correct chain from genesis using only objective work like proof of work. It may need a recent finalized checkpoint from a source the user considers trustworthy.
The issue arises because old validator keys may no longer have economic weight, enabling long-range attack histories if a node has been offline too long. Finality and checkpoint distribution help bound this risk.
Related terms
Proof of Stake (PoS)
→A family of consensus mechanisms in which validators commit stake to propose, attest to, and finalize blocks.
consensus · blockchain
Finality
→The rules or confidence used to judge whether a confirmed transaction can still be reversed.
consensus · blockchain
Validator
→A consensus participant that proposes, verifies, or attests to blocks, often after bonding stake in a proof-of-stake network.
consensus · staking