Replicated Security (RS)

Replicated security (RS) is a shared-security system for the Cosmos ecosystem, in which the validators of the Cosmos Hub also run and secure other blockchains, known as consumer chains. The stake of ATOM held with those validators backs the consumer chains, and misbehaviour on a consumer chain can lead to penalties on the Hub. In return, consumer chains pay part of their fees or token rewards to Hub validators and stakers.

It was the first version of a broader framework called Interchain Security and went live on the Cosmos Hub in 2023. Before it, every Cosmos chain had to attract its own validators and secure itself under proof of stake with the value of its own token, which made new chains expensive to launch and easy to attack. Replicated security brought Cosmos closer to Polkadot's relay chain model. The ATOM token is covered under Cosmos (ATOM).

Picture a large, well-established security firm that guards a city's main bank. A new shop opens nearby and cannot afford to hire and train its own guards. The security firm agrees to send the same trusted guards to watch the shop as well, and the shop pays the firm a share of its takings.

The shop gets protection it could never afford alone, and the guards earn extra money. The catch is that the guards now carry more responsibility, and if they behave badly at the shop, the penalty hits their main job too.

Cosmos chains are built as sovereign appchains that communicate using the Inter-Blockchain Communication protocol. Under replicated security:

1. Approval. A project applies to become a consumer chain, and ATOM holders vote on the proposal through Cosmos Hub governance.
2. Validation. Once approved, the Hub's validators run nodes for the consumer chain as well as the Hub. In the original version, the full active validator set was required to do so.
3. Rewards. The consumer chain sends a share of its block rewards or fees to the Hub, where they are distributed to validators and ATOM stakers.
4. Penalties. Evidence of misbehaviour on a consumer chain, such as signing two conflicting blocks, can be relayed to the Hub, where the validator's staked ATOM can face slashing.

The consumer chain keeps its own application logic and token, but its block production is secured by the same validators and stake as the Hub. Delegators who stake ATOM with a validator share in both the extra rewards and the extra slashing risk, so their choice of validator now covers that validator's conduct on every chain it runs. Consumer chains can also leave the arrangement, or new ones be added, through further governance votes, which makes the set of secured chains a recurring topic in Hub on-chain governance.

Interchain Security was discussed in the Cosmos community for several years before launch. It went live with a Cosmos Hub software upgrade in March 2023. The first consumer chain was Neutron, a smart-contract platform, followed by Stride, a liquid staking chain. In 2024 the Hub adopted a revised model called partial set security, under which validators could opt in to securing particular consumer chains rather than all being obliged to run every one. Replicated security is the name usually used for the original, all-validator version. The change reflected a debate within the community over whether the Hub should act mainly as a security provider for other chains or develop its own applications, a question tied to long-running arguments about the role and tokenomics of ATOM.

• Cheaper launch. New chains gain security from day one without building a validator community or issuing a heavily inflationary token.
• Value for ATOM. Supporters argued that fees from consumer chains would give ATOM stakers a new income stream and a clearer role for the token.
• Validator burden. Requiring every validator to run every consumer chain raised costs, especially for smaller operators, which pushed the move to an opt-in model.
• Less sovereignty. Consumer chains depend on Hub governance and its validator set, giving up some of the independence that drew projects to Cosmos.

Replicated security is one of several attempts to let many chains share one pool of stake. Polkadot's relay chain secures parachains through a single validator set, and on Ethereum restaking lets staked ether back other services. Critics of these models warn that layering more duties onto the same stake can concentrate risk, so that a failure in one place spreads to others. Within Cosmos, the uptake of consumer chains was smaller than early supporters hoped, and some argued that the revenue did not justify the extra load on validators. Supporters reply that shared security remains one of the few ways for small chains to resist a 51% attack or similar takeover cheaply.

• Cosmos Network