Breaking Parallel ROS: Implication for Isogeny and Lattice-based Blind Signatures

ePrint Report: Breaking Parallel ROS: Implication for Isogeny and Lattice-based Blind Signatures

Shuichi Katsumata, Yi-Fu Lai, Michael Reichle

Many of the three-round blind signatures based on identification protocols are only proven to be $\ell$-concurrently unforgeable for $\ell = \mathsf{polylog}(\lambda)$. It was only recently shown in a seminal work by Benhamouda et al. (EUROCRYPT'21) that this is not just a limitation of the proof technique. They proposed an elegant polynomial time attack against the $\ell$-concurrently unforgeability of the classical blind Schnorr …

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