Long Range Attack

A long-range attack is a threat to proof-of-stake blockchains where an attacker creates a fork from the genesis block or an old block to rewrite the history of the chain. Because proof-of-stake does not require physical work, an attacker with enough old private keys can generate a long chain of fake blocks that looks valid to a new node.

This attack can lead to double-spending and the total invalidation of past transactions. It is a major risk for the finality and security of long-term financial records.

Protocols mitigate this through checkpoints and social consensus, where nodes agree on a trusted block height. Understanding this risk is critical for assessing the long-term viability of a blockchain as a settlement layer.

It is a complex issue involving protocol physics and consensus. Managing this risk is essential for the security of institutional-grade financial derivatives on-chain.