The Three Stages of L2 Network Security: From Fundamental Control to Limited Intervention

The security of Ethereum L2 networks can be divided into three stages, primarily depending on the intervention capability of the security committee on the trustless components:

• Stage 0: The Security Committee has full control. Even with a proof system in place, the committee can still overturn its results by a simple majority vote.

• Phase 1: The committee needs more than 75% member approval to override the operating system. There must be a certain number of members from outside the main organization to increase the difficulty of control.

• Stage 2: The committee can only intervene when a clear error occurs. For example, when the results of two redundant proof systems are inconsistent, the committee can only choose from the existing results rather than making arbitrary decisions.

These three stages reflect the gradual decrease in voting weight of the Security Committee. The key issue is how to determine the best timing for transitioning from one stage to the next.

The main reason for the delay in entering Phase 2 is concerns about the reliability of the proof system. The proof system consists of a large amount of code, and potential vulnerabilities could lead to the theft of user assets. Therefore, the stronger the confidence in the proof system, or the weaker the confidence in the security committee, the more the network should be pushed to advance to a higher stage.

By using a simplified mathematical model, we can quantify this process. Assuming that each committee member has a 10% probability of independent failure, and that active failures and safety failures are equally likely. Under these assumptions, we can calculate the probability of system failure at different stages.

The results indicate that as the quality of the proof system improves, the optimal stages transition gradually from 0 to 1, and then to 2. However, the reality is more complex than the model:

• Committee members are not completely independent and may have common mode failures.
• The proof system may consist of multiple independent systems, reducing the overall probability of failure.

These factors make Phase 1 and Phase 2 more attractive than the model predictions.

From a mathematical perspective, Phase 1 seems unnecessary, and the transition should go directly from Phase 0 to Phase 2. However, considering the need for rapid response in emergencies, individual committee members can be granted the authority for short-term withdrawal delays, allowing other members time to take action.

However, entering stage 2 too early also carries risks, especially if it affects the strengthening of the underlying proof system. Ideally, data providers should demonstrate the audit and maturity indicators of the proof system, as well as the current stage.

In summary, the security evolution of L2 networks is a gradual process that requires careful decision-making based on the reliability of the proof system and actual operational conditions. While pursuing decentralization, it is also essential to ensure the overall security and reliability of the system.