TCG CREST is pleased to announce that a paper co-authored by Hrithik Nandi, Sougata Mandal, Avijit Dutta, and Nilanjan Datta has been accepted for presentation at EUROCRYPT 2026, the 45th annual international conference on the theory and applications of cryptographic techniques. This conference is one of the most recognized global conferences in cryptology with a CORE ranking of A*.
This marks the first paper by our student authors to be recognized at EUROCRYPT from TCG CREST, making it a significant milestone for us.
Paper Details:
Title: “How to Build a Short-Input Random Oracle from Public Random Permutations”
Authors: Ritam Bhaumik, Nilanjan Datta, Avijit Dutta, Ashwin Jha, Sougata Mandal, Bart Mennink, Hrithik Nandi, Yaobin Shen
Summary: This paper categorizes all two-call short-input/output Random Permutation (RP) to Random Function (RF) conversion methods and determines what level of indifferentiability they achieve. This contribution includes the introduction of the “chaining attack,” a powerful differentiability attack that disproves security of a wide range of constructions including the sum of a permutation and its inverse, which invalidates an earlier indifferentiability result of Dodis et al., EUROCRYPT’08. On the positive side, the research concludes that only the Sum of Permutations and Encrypted Davies-Meyer Dual, instantiated with independent permutations, achieve indifferentiability beyond the birthday-bound and could potentially be used in counter mode to obtain a parallelizable short-input random oracle. In addition, the paper explores the indifferentiability of expanding RP-to-RF constructions, and demonstrates that XORPw, the core PRF underlying CENC, achieves security beyond the birthday-bound in the public permutation setting.