5 Levels of Cross-Chain Security with Chainlink CCIP
Level 5: Defense-In-Depth
Chainlink is a blockchain-agnostic, decentralized computing platform that provides secure access to external data, off-chain computation, and cross-chain interoperability.
The Chainlink Cross-Chain Interoperability Protocol (CCIP) serves as an interoperability standard for transferring both tokens and/or data between any supported public or private blockchain network.
Level-5 cross-chain security achieves unprecedented levels of decentralization by utilizing multiple decentralized networks to secure a single cross-chain transaction, along with incorporating additional risk management systems to identify risks and take actions to prevent them, such as by implementing emergency shutdowns or imposing rate limits.
The fifth level of cross-chain security doesn’t just give you one independent network for your cross-chain data or messages; it gives you multiple networks, made up of independent nodes all working together to secure each bridge.
While many bridge solutions operate using a single node or multiple nodes under the control of one key holder (e.g., Multichain), the fifth level of security uses multiple independent nodes with their own independent key holders and even splits them up into two separate groups of nodes: the transactional DON nodes and the Risk Management Network nodes. One additional key feature of the separate networks in CCIP is the creation of two entirely separate implementations, with two independent code bases, so that CCIP features an unprecedented level of client diversity/decentralization for cross-chain interoperability.
Developed with security and reliability as the primary focus CCIP operates at the highest level of cross-chain security. CCIP’s defense-in-depth security and suitability can be broken down across four categories:
Multiple Layers of Decentralization
CCIP is underpinned by Chainlink’s proven decentralized oracle infrastructure. Rather than operating as a single monolithic network, CCIP is composed of multiple decentralized oracle networks (DONs) per chain lane, each consisting of a unique source chain and destination chain. This approach allows CCIP to be horizontally scalable, as additional DONs are added to CCIP for each additional blockchain network supported, versus funneling all cross-chain traffic through a single network.
The committing DON is a decentralized network of oracle nodes that monitor events on a given source chain, wait for source chain finality, bundle transactions to create a Merkle root, come to consensus on that Merkle root and finally commit that Merkle root to the destination chain. The executing DON is a decentralized network of oracle nodes that submit Merkle proofs on a destination chain, which is then verified onchain by ensuring the transactions were included in a previously committed Merkle root that has been validated by the Risk Management Network.
Risk Management Network
The Risk Management Network is a separate, independent network that continuously monitors and validates the behavior of CCIP, providing an additional layer of security by independently verifying cross-chain operations for anomalous activity. The Risk Management Network utilizes a separate, minimal implementation of the Chainlink node software, creating a form of client diversity for increased robustness while also minimizing external dependencies to prevent supply chain attacks.
More specifically, the Risk Management Network was written in a different programming language (Rust) than the primary CCIP system (Golang), developed by a different internal team, and uses a distinct non-overlapping set of node operators compared to the CCIP DONs. The Risk Management Network is a wholly unique concept in cross-chain interoperability that builds upon established engineering principles (N-version programming) seen in mission-critical systems in industries such as aviation, nuclear, and machine automation.
To increase the security and robustness of CCIP, the Risk Management Network engages in two types of activities:
Secondary Approval: The Risk Management Network independently recreates Merkle roots based on transactions from the source chain, which are then published on the destination chain and compared against the Merkle roots published by the Committing DON. Cross-chain transactions can only be executed if the Merkle roots from the two networks match.
Anomaly Detection: The Risk Management Network monitors for abnormal behavior from the CCIP network (e.g., committed transactions with no source chain equivalent) as well as the behavior of chains (e.g., deep block reorgs). If suspicious activity is detected, the Risk Management Network can trigger an emergency halt to pause all CCIP lanes and limit any losses.
High-Quality Node Operators
Chainlink DONs are operated by a geographically distributed collection of Sybil-resistant, security-reviewed node operators with significant experience running mission-critical infrastructure across Web2 and Web3. Node operators in the Chainlink ecosystem include global enterprises (e.g., Deutsche Telekom MMS, Swisscom, Vodafone), leading Web3 DevOps teams (e.g. Infura, Coinbase Cloud), and experienced Chainlink ecosystem projects.
The Committing DONs and Executing DONs in CCIP are composed of 16 high-quality independent node operators, while the Risk Management Network is composed of 7 distinct node operators (resulting in a total of 23 node operators). Importantly, the Risk Management Network consists of a wholly separate and non-overlapping set of nodes compared to the primary CCIP networks, helping ensure independent secondary validation. As the value secured by CCIP expands over time, the number of node operators within each network can scale to meet the need for greater security.
Configurable Rate Limits
As an additional layer of security for cross-chain token transfers, CCIP implements configurable rate limits, established on a per-token and per-lane basis, which are set up in alignment with the token contract owners like Lido. Furthermore, CCIP token transfers also benefit from the increased security provided by an aggregate rate limit (across token pools) on each lane, so even in a worst-case scenario, it would be impossible for every token’s limit to be maxed out before the aggregate rate limit on a lane is hit.
Conclusion
With CCIP you get:
Multiple independent nodes run by independent key holders.
Three decentralized networks all executing and verifying every bridge transaction.
Separation of responsibilities, with distinct sets of node operators, and with no nodes shared between the transactional DONs and the Risk Management Network.
Increased decentralization with two separate code bases across two different implementations, written in two different languages to create a previously unseen diversity of software clients in the bridging world.
Never-before-seen level of risk management that can be rapidly adapted to any new risks or attacks that appear for cross-chain bridging.
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