Weak Subjectivity Period

Definition ∞ A weak subjectivity period in proof-of-stake blockchains refers to a specific timeframe during which a newly joining node must rely on a trusted external source to determine the correct chain history. Beyond this period, the node can verify the chain’s validity independently using only on-chain data, assuming a majority of validators are honest. This mechanism balances the need for efficient synchronization with maintaining decentralized security without requiring full historical validation. It mitigates long-range attacks.
Context ∞ The weak subjectivity period is a crucial concept in the security model of proof-of-stake blockchains, frequently discussed in news surrounding network upgrades and the onboarding of new validators. Its proper configuration is vital for ensuring network integrity against certain types of attacks, particularly for chains with a long history. Debates often focus on optimizing this period to balance security assurances with the practicalities of node operation and network decentralization.