Indifferentiability is used to analyze the security of constructions of idealized objects, such as random oracles or ideal ciphers. Reset indifferentiability is a strengthening of plain indifferentiability which is applicable in far more scenarios, but is often considered too strong due to significant impossibility results. Our main results are: - Under weak reset indifferentiability, ideal ciphers imply (fixed size) random oracles and random oracle domain shrinkage is possible. We thus...

The equivalence of the random-oracle model and the ideal-cipher model has been studied in a long series of results. Holenstein, Künzler, and Tessaro (STOC, 2011) have recently completed the picture positively, assuming that, roughly speaking, equivalence is indifferentiability from each other. However, under the stronger notion of reset indifferentiability this picture changes significantly, as Demay et al. (EUROCRYPT, 2013) and Luykx et al. (ePrint, 2012) demonstrate. We complement these...

The indifferentiability framework by Maurer, Renner and Holenstein (MRH; TCC 2004) formalizes a sufficient condition to safely replace a random oracle by a construction based on a (hopefully) weaker assumption such as an ideal cipher. Indeed, many indifferentiable hash functions have been constructed and could since be used in place of random oracles. Unfortunately, Ristenpart, Shacham, and Shrimpton (RSS; Eurocrypt 2011) discovered that for a large class of security notions, the MRH...

The indifferentiability framework of Maurer, Renner, and Holenstein (MRH) has gained immense popularity in recent years and has proved to be a powerful way to argue security of cryptosystems that enjoy proofs in the random oracle model. Recently, however, Ristenpart, Shacham, and Shrimpton (RSS) showed that the composition theorem of MRH has a more limited scope than originally thought, and that extending its scope required the introduction of reset-indifferentiability, a notion which no...

Ristenpart et al. showed that the limitation of the indifferentiability theorem of Maurer et al. which does not cover all multi stage security notions but covers only single stage security notions, defined a new concept (reset indifferentiability), and proved the reset indifferentiability theorem, which is an analogy of the indifferentiability theorem covers all security notions S: if H^U is reset indifferentiable from RO, for any security notion, a cryptosystem C is at least as secure in...

We exhibit a hash-based storage auditing scheme which is provably secure in the random-oracle model (ROM), but easily broken when one instead uses typical indifferentiable hash constructions. This contradicts the widely accepted belief that the indifferentiability composition theorem applies to any cryptosystem. We characterize the uncovered limitation of the indifferentiability framework by show- ing that the formalizations used thus far implicitly exclude security notions captured by...