Vitalik Buterin outlines new Ethereum PoS strategy for post-Shanghai era

In a detailed blog post dated Dec. 27, Ethereum founder Vitalik Buterin outlined a significant shift in Ethereum’s approach to Proof-of-Stake (PoS) validation following its Shanghai upgrade.

Ethereum currently supports many validators, with approximately 895,000 validator objects enabling a broad individual and entity participation base. This is a key feature of Ethereum’s decentralized structure.

However, this model presents technical challenges, notably the processing of an immense number of signatures. About 28,000 signatures are required to validate a block today; that number is projected to reach 1.79 million post-SSF (Sharding and Staking Finality).

The technical sacrifices for supporting such a load are considerable. They include complex attestation propagation mechanisms, the need for hyper-optimized BLS signature operations, the lack of a viable quantum-resistant alternative, and increased slot times due to more sub-slots.

Buterin also highlights the current model’s systemic complexity and potential ineffectiveness in truly democratizing staking, as the minimum staking requirement of 32 ETH remains financially prohibitive for many.

8,192 signatures

In response, Buterin proposes a pivot that would reduce the number of signatures per slot to a manageable 8,192. This change, he argues, would open up the PoS design space, allow technical simplification, improve security, and address quantum resistance concerns.

Buterin critiques the committee-based security approach used by other blockchains, emphasizing the lack of accountability and insufficient deterrents against attacks. Ethereum, in contrast, imposes severe penalties on attackers. Still, Buterin suggests that even a reduced cost of attack (1-2 million ETH) would be sufficient, advocating for a balanced solution that maintains high penalties but offers more benefits than a smaller validator set.

The blog post explores three approaches for implementing the 8,192 signatures per slot under SSF:

1. Decentralized Staking Pools: Focusing solely on decentralized stake pools, potentially raising the minimum deposit size, and capping penalties to reduce trust in node operators.
2. Two-Tiered Staking: Establish a “heavy” layer for major stakers involved in finalization and a “light” layer for additional security, with no minimum stake requirement.
3. Rotating Participation (Accountable Committees): A hybrid approach where validators participate based on their stake, ensuring safety through carefully adjusted validator sets.

Buterin’s conclusion emphasizes that sticking to 8,192 signatures would greatly simplify technical implementation and make Ethereum more accessible. The focus would then shift to choosing the most suitable approach from the proposed options.

Security through simplicity

Some users raised concerns in the comments about designing systems resilient against state attackers, suggesting that even a reduced security budget might be insufficient. Buterin responded by emphasizing the importance of simplicity in protocol design as a means of defense against various attack vectors, advocating for “security through simplicity.”

This proposed shift signifies a pivotal moment in Ethereum’s ongoing development, highlighting the constant balance of security, decentralization, and usability.