How Does “Checkpointing” or “Social Consensus” Mitigate the Long-Range Attack Risk in PoS?

Checkpointing and social consensus mitigate the long-range attack risk in Proof-of-Stake (PoS) by establishing an agreed-upon, irreversible point in the chain's history. Checkpointing is a protocol-level mechanism that hardcodes a block as final.

Social consensus is the community's collective agreement on the legitimate chain. For a long-range attack to succeed, the attacker's chain must be accepted by the network.

By relying on checkpoints and the community's established history, nodes will reject any alternative chain that starts before the agreed-upon final block.