International Association
for Cryptologic Research

We continue the study of blockcipher-based (tweakable) correlation robust hash functions, which are central building blocks of circuit garbling and oblivious-transfer extension schemes. As results, we first enhance the multi-user tweakable correlation robust notion of Guo et al. (CRYPTO 2020) with a {\it key leaking oracle} that tells the adversary whether a certain user key satisfies the adversarially-chosen predicate. We then investigate the state-of-the-art hash construction of Guo et al. with respect to our new security definition, providing security proof as well as matching attacks. As an application, we exhibit an OT extension protocol with non-trivial multi-user security.