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Fiat–Shamir Bulletproofs are Non-Malleable (in the Algebraic Group Model)

2022; Springer Science+Business Media; Linguagem: Inglês

10.1007/978-3-031-07085-3_14

1611-3349

Chaya Ganesh, Claudio Orlandi, Mahak Pancholi, Akira Takahashi, Daniel Tschudi,

Security and Verification in Computing

Bulletproofs (Bünz et al. IEEE S&P 2018) are a celebrated ZK proof system that allows for short and efficient proofs, and have been implemented and deployed in several real-world systems. In practice, they are most often implemented in their non-interactive version obtained using the Fiat-Shamir transform, despite the lack of a formal proof of security for this setting. Prior to this work, there was no evidence that malleability attacks were not possible against Fiat-Shamir Bulletproofs. Malleability attacks can lead to very severe vulnerabilities, as they allow an adversary to forge proofs re-using or modifying parts of the proofs provided by the honest parties. In this paper, we show for the first time that Bulletproofs (or any other similar multi-round proof system satisfying some form of weak unique response property) achieve simulation-extractability in the algebraic group model. This implies that Fiat-Shamir Bulletproofs are non-malleable.