Definition ∞ A history revision attack involves an attempt to alter previously confirmed transactions or blocks on a blockchain. This malicious action seeks to rewrite the established, immutable record of a blockchain ledger by creating an alternative chain of blocks that contradicts the accepted history. Such an attack, if successful, undermines the fundamental security and trust properties of a decentralized network, potentially leading to double-spending or invalidating past settlements. It represents a severe threat to data integrity and finality.
Context ∞ History revision attacks are a primary security concern for blockchain protocols, particularly those with lower hash rates or smaller validator sets. Robust consensus mechanisms and sufficient network decentralization are designed to make such attacks economically infeasible. News often discusses the resilience of various blockchains against these threats, especially after significant network events or protocol upgrades.
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