What is Shared Security?

Shared security in blockchain refers to the concept of a smaller or less secure blockchain borrowing security resources from a larger, more established blockchain network. The core idea is that the smaller blockchain can inherit the security of the larger blockchain, making it more resistant to attacks like 51% attacks.

There are a few key ways that shared security can be implemented:

Rollups

Rollups are a Layer 2 blockchain protocol that implements shared security model. Rollups move transactions off the main blockchain (Layer 1) into the rollup's own environment, batching them and recording a state update on the Layer 1 chain. This allows the rollup transactions to enjoy the same level of security as the main blockchain.

Related Reading: What is Rollup?

Polkadot Parachain

Polkadot's parachain system implements a shared security model. Parachains connected to the Polkadot Relay Chain all share in the security provided by the Relay Chain's validator set. The Relay Chain has a large, decentralized pool of validators that secure the entire network. This means parachains do not need to individually bootstrap and maintain their own validator networks, but can instead leverage the security of the Relay Chain.

Interchain Security

In an interchain model like Cosmos' Interchain Security, other blockchains can lease access to the Cosmos Hub's validator set. The Cosmos Hub validators will then validate transactions on these consumer chains in exchange for staking rewards. Misbehavior by a validator on a consumer chain can result in their stake being slashed on the Cosmos Hub.

EigenLayer's Shared Security Model

EigenLayer is a blockchain protocol that implements a shared security model, allowing smaller or less secure blockchains to leverage the security of the Ethereum network. The core of EigenLayer's approach is "restaking" - where users can stake their Ethereum (ETH) or liquid staked ETH tokens (like stETH, rETH, etc.) on the EigenLayer protocol. This staked ETH can then be used to provide security and validation services to other blockchain protocols, known as "Actively Validated Services" (AVSs).

Related Reading: What is EigenLayer?

The key benefits of shared security include:

• Security for Smaller Chains: Smaller blockchains can be vulnerable to 51% attacks, but shared security makes these attacks more difficult by tying their security to a larger, more established chain.
• Increased Scalability: Secure blockchains like Bitcoin and Ethereum often have limited scalability. Shared security enables transactions to be moved off these chains while still leveraging their improved security.
• Expanded Feature Sets: Shared security allows new blockchains to offer specialized features and optimizations while still enjoying the security of a larger network.