Generic Indifferentiability Proofs of Hash Designs

Marion Daubignard (1) , Pierre-Alain Fouque (2) , Yassine Lakhnech (3)

1 DGA - Délégation générale de l'armement
2 LIENS - Laboratoire d'informatique de l'école normale supérieure
3 VERIMAG - IMAG - VERIMAG

—In this paper, we propose a formal analysis of domain extenders for hash functions in the indiffer-entiability framework. We define a general model for domain extenders and provide a unified proof of their security in the form of a generic reduction theorem. Our general model for domain exenders captures many iterated constructions such as domain extenders, modes of operation of symmetric cryptography such as CBC-MAC or blockciphers based on Feistel networks. Its proof has been carried out using the Computational Indistin-guishability Logic of Barthe et al.. The theorem can help designers of hash functions justifying the security of their constructions: they only need to bound the probability of well-defined events. Our model allows to consider many SHA-3 finalists and is instantiated on two well-known constructions, namely Chop-MD and Sponge. Finally, the indifferentiability bounds which we prove are convincing since they match previous proofs.

Domaines: Cryptographie et sécurité [cs.CR]

Marion Daubignard, Pierre-Alain Fouque, Yassine Lakhnech. Generic Indifferentiability Proofs of Hash Designs. 25th {IEEE} Computer Security Foundations Symposium, {CSF} 2012, Jun 2012, Cambridge, United States. pp.14, ⟨10.1109/CSF.2012.13⟩. ⟨hal-01094323⟩