Black-box property of cryptographic hash functions

Abstract

We define a new black-box property of cryptographic hash function families H:{0,1} K ×{0,1} * → {0,1} y which guarantees that for a randomly chosen hash function H K from the family, everything "non-trivial" we are able to compute having access to the key K, we can compute only with oracle access to H K . If a hash function family is pseudo-random and has the black-box property then a randomly chosen hash function H K from the family is resistant to all non-trivial types of attack. We also show that the HMAC domain extension transform is Prf-BB preserving, i.e. if a compression function f is pseudo-random and has the black-box property (Prf-BB for short) then HMAC f is Prf-BB. On the other hand we show that the Merkle-Damgård construction is not Prf-BB preserving. Finally we show that every pseudo-random oracle preserving domain extension transform is Prf-BB preserving and vice-versa. Hence, Prf-BB seems to be an all-in-one property for cryptographic hash function families, which guarantees their "total" security. © 2012 Springer-Verlag.