Solana Speed Plan Risks Unverified Validator Data

A recent proposal for the Solana network aims to significantly increase block production speed by reordering validator assignments based on geographic proximity. The plan, detailed in a draft called SIMD-0675 by researchers from ETH Zurich and Anza, suggests grouping validators that report being physically close to each other. This would allow for faster "handovers" of block-building responsibilities between consecutive validators, potentially reducing average handover delays.

The core innovation lies in creating "bins" of nearby validators. While the total number of block-building opportunities, known as leader windows, for each validator would remain the same, their timing would change. This grouping is intended to benefit validators located further from major stake concentrations, as they would face shorter network hops to the preceding validator. The authors' simulations suggest this could cut average handover delays from over 36 milliseconds to around 17 milliseconds.

However, a key challenge is that the system relies on validators self-reporting their locations. Solana would not have a mechanism to verify this geographic data, introducing a potential point of vulnerability. The proposal explicitly acknowledges this tension, with simulations indicating the possibility of adversarial actors manipulating their reported locations to gain advantages, such as extended control over block production. The proposal is currently under review.