The Security Challenges of Cross-Chain Protocols and the Importance of Decentralization

In recent years, cross-chain protocols have played an increasingly important role in the blockchain field. However, as their application scope expands, security issues have also become more prominent. According to data from the past two years, the losses caused by security incidents related to cross-chain protocols rank first among various blockchain security events, and their importance even surpasses that of Ethereum scaling solutions.

The interoperability between cross-chain protocols is an inherent need for the development of the Web3 ecosystem. Such projects often receive significant funding, and their total locked value (TVL) and trading volume continue to grow. However, ordinary users often find it difficult to accurately assess the security levels of these protocols, which increases potential risks.

Taking a well-known cross-chain protocol as an example, its design architecture appears simple, but in fact, there are potential risks. The protocol uses Relayer to execute inter-chain communication, supervised by Oracle. This design, while eliminating the traditional third-chain consensus verification process and providing users with a "fast cross-chain" experience, also brings security vulnerabilities.

Firstly, simplifying multi-node validation to a single Oracle validation undoubtedly significantly reduces the security factor. Secondly, this design must assume that the Relayer and Oracle are completely independent, but this trust assumption is difficult to guarantee permanently in practical operations, lacking sufficient Decentralization characteristics.

Some believe that opening up Relayer access permissions can enhance security. However, this approach essentially just increases the number of participants and does not fundamentally change the product characteristics or improve security. On the contrary, it may introduce new problems.

If a cross-chain project allows modifications to its node configuration, an attacker could potentially replace it with nodes they control, thereby forging messages. This risk may be exacerbated in complex scenarios. Moreover, since end users need to assess the security of each project using the protocol on their own, this undoubtedly increases the difficulty of ecosystem development.

A truly decentralized infrastructure should provide consistent security for all projects within its ecosystem. However, some projects that claim to be infrastructure are actually more like middleware (Middleware), allowing application developers to customize security policies but failing to ensure the overall security of the ecosystem.

Some security teams have pointed out potential vulnerabilities in certain cross-chain protocols. For example, if an attacker gains access to the protocol's configuration, they may change the oracles and relayers to components they control, thereby manipulating cross-chain transactions. Additionally, there are vulnerabilities that allow messages to be modified after oracles and multi-signatures have been signed, which could lead to users' funds being stolen.

Looking back at the Bitcoin white paper, we can see that a true decentralized system should be peer-to-peer, without relying on trusted third parties. This "Satoshi consensus" emphasizes the importance of trustlessness ( Trustless ) and decentralization ( Decentralized ). However, certain self-proclaimed decentralized cross-chain protocols still rely on multiple trusted roles, which contradicts the true concept of decentralization.

Building a truly decentralized cross-chain protocol remains a huge challenge. Some emerging technologies, such as zero-knowledge proofs, may provide new ideas for solving this problem. In any case, only protocols that truly achieve decentralization security can stand firm in the future blockchain ecosystem.