Differentiability of four prefix-free PGV hash functions

Abstract

A Preneel-Govaerts-Vandewalle hash function with a prefix-free padding method (PF-PGV hash function) is a block-cipher-based iterative hash function. Chang et al. claimed that 16 PF-PGV hash functions were indifferentiable from a random oracle. This letter shows that 4 out of 16 PF-PGV hash functions are not indifferentiable from a random oracle.