Long Range Attacks

Long range attacks target the finality and history of a blockchain by creating an alternative chain starting from a very old block. The attacker uses their private keys to generate a chain that diverges from the honest main chain at a point far in the past.

Because the protocol rules may not adequately differentiate between this fake long history and the legitimate one, new nodes joining the network might be tricked into syncing with the fraudulent chain. This is a specific risk in Proof of Stake systems where historical keys can be repurposed if not properly managed by checkpointing.

By successfully deceiving nodes, the attacker can rewrite significant portions of the transaction history. This threat necessitates robust protocols for secure node synchronization and periodic finality markers.