Equivocation

In the context of distributed ledger technology and blockchain consensus, equivocation refers to the act of a validator or node proposing two different, conflicting versions of the same block or state update to different parts of the network simultaneously. This is a malicious or erroneous behavior that undermines the fundamental principle of a single, immutable ledger.

By sending different data to different peers, an attacker attempts to cause a fork in the blockchain, potentially enabling a double-spend attack where the same digital asset is effectively spent twice. Equivocation is a critical threat to safety in consensus protocols, particularly those utilizing Proof of Stake, where finality depends on honest validator behavior.

Modern protocols implement slashing mechanisms to penalize validators who are caught equivocating, ensuring that the cost of such behavior outweighs any potential gain. It is a core challenge in maintaining the integrity of decentralized systems without a central clearinghouse.