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UBITECH presents a work on expressive designated verifier anonymous credentials at ARES 2023

Dr Thanassis Giannetsos, Head of UBITECH’s Digital Security & Trusted Computing Research Group, and his co-author introduce RETRACT, an innovative and comprehensive anonymous credential scheme, at the 18th International Conference on Availability, Reliability and Security (ARES 2023), that is held August 29 – September 1, 2023 in Benevento, Italy. In particular, RETRACT enables credential holders to demonstrate their possession of satisfying credentials for any given predicate, while ensuring that only the intended verifier can validate them.

Their approach effectively combines cutting-edge commit-carrying zkSNARK constructions with the extensively utilized BBS+ signature scheme. Furthermore, their evaluation illustrated that designating the verifier in the proofs has minimal impact on circuit complexity (depending on the choice of trapdoor), requires only two additional exponentiations in the Schnorr protocol, and only increases presentation size by a constant factor 𝜆 attributed to the disjunction operation (split challenge).