In light of the results of RSS, we set out to rigorously tackle the specifics of indifferentiability and reset-indifferentiability by viewing the notions as special cases of a more general definition. Our contributions are twofold. Firstly, we provide the necessary formalism to refine the notion of indifferentiability regarding composition. By formalizing the definition of stage minimal games we expose new notions lying in between regular indifferentiability (MRH) and reset-indifferentiability (RSS).
Secondly, we answer the open problem of RSS by showing that it is impossible to build any domain extender which is reset-indifferentiable from a random oracle. This result formally confirms the intuition that reset-indifferentiability is too strong of a notion to be satisfied by any hash function. As a consequence we look at the weaker notion of single-reset-indifferentiability, yet there as well we demonstrate that there are no ``meaningful'' domain extenders which satisfy this notion. Not all is lost though, as we also view indifferentiability in a more general setting and point out the possibility for different variants of indifferentiability.Category / Keywords: foundations / indifferentiability, reset-indifferentiability, random oracle, hash functions Date: received 13 Nov 2012 Contact author: atul luykx at esat kuleuven be Available format(s): PDF | BibTeX Citation Version: 20121120:104756 (All versions of this report) Short URL: ia.cr/2012/644 Discussion forum: Show discussion | Start new discussion