Security Challenges of Cross-Chain Protocols and the Limitations of LayerZero

In the Web3 ecosystem, the importance of cross-chain protocols is becoming increasingly prominent. However, recent security incidents have shown that these protocols carry significant potential risks. In fact, losses caused by cross-chain protocols rank first among various blockchain security incidents, and their importance even surpasses Ethereum's scaling solutions.

Some cross-chain protocols have seemingly simple designs, but that does not mean they are excellent or secure solutions. Taking a well-known cross-chain protocol as an example, its architecture, while concise, has obvious security risks.

The basic architecture of the protocol is as follows: Communication between Chain A and Chain B is executed by the Relayer, while the Oracle is responsible for supervising the Relayer. Although this design avoids the complex process of requiring a third chain to achieve consensus, providing users with a fast cross-chain experience, it also brings significant security risks.

First, simplifying multi-node verification to a single Oracle verification significantly reduces the security factor. Second, this design must assume that the Relayer and Oracle are completely independent, a hypothesis that is difficult to guarantee permanently in reality, posing a risk of collusion.

Some may think that increasing the number of Relayers can enhance security. However, this approach does not fundamentally solve the problem. Increasing the number of participants does not equate to decentralization, nor does it change the essential characteristics of the product.

More importantly, if a project using this protocol allows modification of configuration nodes, an attacker could replace them with nodes they control, thereby forging messages. This risk becomes more severe in complex scenarios, and the protocol itself does not have the capability to address this issue.

Some security research teams have pointed out potential vulnerabilities in this protocol. For example, if the application owner or private key holder behaves improperly, it could lead to user assets being stolen. Further research has found that there are critical vulnerabilities in the protocol's relayers that could be exploited by insiders or team members with known identities.

A true decentralized cross-chain protocol should adhere to the core principle of "Satoshi Nakamoto consensus," which is to eliminate trusted third parties and achieve true trustlessness and decentralization. However, some self-proclaimed decentralized cross-chain protocols do not actually meet these standards. They may require users to trust that multiple parties will not collude to act maliciously, or treat application developers as trusted third parties.

Building a truly decentralized cross-chain protocol is a daunting task. It not only requires avoiding the introduction of trusted third parties in the design but should also be able to generate fraud proofs or validity proofs and verify these proofs on-chain. Only then can true decentralization and trustlessness be achieved.

When evaluating cross-chain protocols, we should not be misled by superficial simplicity in design or massive funding. Truly secure and decentralized cross-chain solutions require more effort in technical design and implementation, and may need to leverage advanced technologies such as zero-knowledge proofs to enhance security and decentralization.

In the future, only those protocols that can achieve true decentralized security will stand out in the fierce competition, providing reliable cross-chain infrastructure for the Web3 ecosystem.