Double-Signing

Double-signing occurs in a distributed ledger network when a validator or miner signs two different blocks or messages for the same block height or slot. This action is a direct violation of consensus rules intended to ensure a single, immutable version of the truth.

In a Proof-of-Stake system, this behavior is often malicious, aiming to facilitate a double-spend attack by creating a fork in the blockchain. Because the network requires validators to be honest to maintain security, protocols include mechanisms to detect such activity.

Once detected, the protocol typically slashes a portion of the validator's staked assets as a financial penalty. This deterrent is essential for maintaining the integrity of decentralized consensus mechanisms.

Without strict penalties for double-signing, participants could exploit the system to rewrite history or reverse transactions. It is a critical concept in understanding how trust is mathematically enforced without a central authority.

Ultimately, double-signing is the fundamental threat that consensus algorithms are designed to prevent.