Ethereum's Vitalik Buterin Proposes Hybrid-Proof Architecture for L2 Rollups
2min read Ethereum co-founder Vitalik Buterin has introduced a new framework aimed at enhancing the security and finality of Layer-2 (L2) rollups within the Ethereum ecosystem. This proposal focuses on a hybrid-proof architecture that integrates zero-knowledge proofs, optimistic rollups, and trusted execution environments (TEEs), ensuring a balanced and robust security model without over-reliance on any single system.
Buterin's roadmap comes at a critical juncture as Ethereum's L2 landscape continues to evolve. Several rollups have already reached Stage 1 on Ethereum’s scaling roadmap, with upcoming upgrades like Pectra and Fusaka poised to significantly expand the availability of data blobs for rollup use. The next phase, Stage 2, requires a higher degree of trustlessness and faster transaction finality, which Buterin believes can be achieved through a three-prover system. This system mandates that two out of three mechanisms—zero-knowledge (ZK) prover, optimistic prover, and TEE prover—must validate a rollup’s state root to achieve finality.
Under this model, if both a ZK prover and a TEE prover approve a state root, the result is finalized immediately. If only one approves, the system defaults to an optimistic model that requires a seven-day challenge period. This optimistic layer acts as a final arbiter, preventing semi-trusted systems from overriding decisions when more trustless systems disagree. Buterin emphasized that this architecture is designed to meet the specific security and decentralization goals outlined for Stage 2 rollups, providing fast finality in normal operations and ensuring that trust-minimized proof systems cannot be overridden by semi-trusted components.
To further safeguard the system, Buterin proposed a security council that would have the authority to immediately upgrade the TEE logic in case of failure and make delayed changes to the ZK or optimistic systems. In rare scenarios where provers produce contradicting outcomes, the council would intervene instantly to preserve system integrity. Buterin believes that this combination of one ZK prover, one optimistic prover, and one TEE represents the only viable way to achieve Ethereum’s Stage 2 goals without sacrificing speed or security. ZK and optimistic proof (OP) systems are based on fundamentally different mathematical assumptions, making the likelihood of shared vulnerabilities extremely low. Pairing them with a TEE strikes a practical balance that is unlikely to fail in tandem.
Beyond the proof architecture, Buterin also addressed Ethereum’s evolving data layer. The Pectra upgrade, expected within a few weeks, will increase blob space to six units per block. A subsequent upgrade, Fusaka, could boost that number to as many as 72, drastically expanding the data bandwidth available to rollups. More blob space reduces congestion and makes L2 transactions cheaper and more scalable. Buterin also highlighted the need for a standardized, ecosystem-wide proof aggregation layer. This layer would allow applications across the Ethereum stack to combine their outputs into a single, unified proof, dramatically lowering gas costs by spreading the roughly 500,000 gas burden of proof submission across all participants.
Ask Aime: What impact will Buterin's hybrid-proof architecture have on Ethereum's L2 rollups and overall scalability?
As these systems mature and eliminate critical bugs, TEEs could eventually be phased out entirely. In that scenario, Ethereum rollups would achieve full trustlessness, with instant finality and zero reliance on semi-trusted components. Buterin noted that the Ethereum community is already on track to produce ZK-EVMs capable of generating proofs within a single slot, even under worst-case conditions. This roadmap represents a significant step forward in Ethereum’s quest for enhanced security and scalability, ensuring that the network remains robust and efficient as it continues to grow.
