Title: Revisiting Simulation Extractability in the Updatable Setting

Abstract: We revisit the notion of Simulation Extractability (SE) for SNARKs in the updatable setting. We demonstrate that existing formal definitions of SE in this setting are insufficient to guarantee the required non-malleability in real-world scenarios. Towards this, we first identify and frame a malleability vulnerability: a cross-SRS reinterpretation attack, which shows that an adversary can reuse or maul proofs across different, correlated SRSs generated through the update procedure. This is made possible because existing security definitions fail to model an adversary’s ability to observe simulated proofs relative to various derived SRSs. To close this security gap, we propose a revised and stronger security notion of Updatable Simulation Extractability. Our definition models a dynamic environment where the SRS is adaptively updatable by the adversary, who can also query simulation oracles for proofs under the resulting family of reachable SRSs. This captures the full extent of the adversarial capabilities observed in practice.

https://eprint.iacr.org/2025/2117.pdf

About the Speaker: Hamidreza Khoshakhlagh is a Postdoc in the Cryptograpy and Cybersecurity Section