shared security

A new blockchain faces a bootstrapping problem: its security comes from the value staked or mined to protect it, and a young chain has little of either, making it cheap to attack. Shared security solves this by letting many chains borrow the economic security of an established base layer's validators, instead of each painstakingly building its own. One large, well-capitalized validator set protects several chains at once.

Different ecosystems implement this differently. Polkadot's relay chain validators provide pooled security to all its parachains: the parachains do not run their own consensus, they inherit the relay chain's. Cosmos's Interchain Security lets the Cosmos Hub's validators also validate a consumer chain, so the consumer rents the Hub's stake and the Hub's validators earn extra rewards (and face extra slashing). EigenLayer takes a different angle: Ethereum stakers opt in to also secure other services, extending Ethereum's staked capital outward. In every case, attacking the protected chain now means contending with the full economic weight of the base layer.

The benefit is obvious — instant, large-scale security for chains that could never afford it alone — but it concentrates risk and entangles fates. Validators now have obligations across multiple chains, slashing conditions multiply, and a bug or correlated failure in one protected service can cascade to the shared validators and thus to everything they secure. Shared security is powerful precisely because it pools stake, and dangerous for exactly the same reason: it also pools systemic risk.