Buterin proposes 'security through simplicity' to lighten Ethereum staking

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Ethereum co-founder Vitalik Buterin has published a new proposal that seeks to reduce the required number of signatures from validators to streamline the Ethereum network’s proof-of-stake consensus mechanism.

A PoS simplification proposal: make a design that only requires 8192 signatures per slot (even with SSF), making the consensus implementation considerably simpler and lighter.https://t.co/Z8mK7vZx7g

— vitalik.eth (@VitalikButerin) December 27, 2023

According to Buterin, the proposal aims to make Ethereum’s consensus implementation “considerably simpler and lighter” by reducing the signature requirement per slot from roughly 28,000 to just 8,192 signatures.

To date, Ethereum has roughly 895,000 validators, with each validator being required to stake 32 ether (ETH) and become activated within the network. Ethereum does this to maintain decentralization and open access for more participants to help with staking, but this also results in more load on the network because of processing requirements.

“The signature aggregation system feels reasonable at first glance, but in reality it creates systemic complexity that bleeds out all over the place,” Buterin said.

With Buterin’s proposal, the signature load for future upgrades would be predictable and limited, simplifying protocol and infrastructure development efforts. However, this also means that Ethereum’s network load could still be increased through hard forks.

Buterin points out that such a system opens up compromises, limiting quantum security, complicated upgrades, and an apparent reliance on zero-knowledge proofs to manage scale.

Buterin believes that his proposal will simplify the proof-of-stake design and allow for a “large amount of technical simplification.”

“[…] instead of relying on cryptographers to create magic bullets (or magic bulletproofs) to make an ever-increasing number of signatures per slot possible, I propose that we make a philosophical pivot: move away from having such an expectation in the first place,” the Ethereum co-founder stated.

The proposal provides three approaches to enable the reduction of required signatures: a shift to prioritizing reliance on decentralized staking pools, a two-tier system that provides options for “heavy” and “light” staking, and rotating validator subsets through committees.

The first approach suggests that Ethereum could discard direct access to the consensus layer in favor of using decentralized staking pools exclusively, raising deposit minimums but capping pool-related penalties to avoid over-reliance on operators.

In the second method, a two-tiered approach creates heavy-stake validators specifically assigned to finalize blocks. This is then supplemented by a lighter security layer that has no minimum thresholds to participate.

The third approach proposes a set construction that is proportional to a validator’s stake weight and rotates participants dynamically.

Buterin notes that the third approach effectively decouples weight for incentive purposes (validator rewards) from stake weight for consensus purposes. This means that each validator’s reward within the committee (based on an agreed-upon rotation) should be the same, keeping average rewards proportional to the balance.

“The future load of the Ethereum protocol becomes no longer an unknown: it can be raised in the future through hard forks, but only when developers are confident that technology has improved enough to be able to handle a larger number of signatures-per-slot with the same level of ease,” Buterin said.

The main tradeoff is between a significant reduction in validator participation per slot and increased technical feasibility and flexibility. The proposal aims to balance the network’s decentralization and scalability, but its critics argue that the changes it carries may diverge from Ethereum’s core philosophy.

While the purpose of improving Ethereum’s scalability with a leaner signature scheme may appear to be well-meaning, commentators on Vitalik’s proposal have raised concerns about possible security flaws due to the reduced complexity, which may open new attack vectors if any of the three approaches are implemented. To this end, Buterin responded that streamlining the protocol design offers “security through simplicity” while enhancing the network’s resilience against state-level attacks.

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