Indifferentiability of SKINNY-HASH Internal Functions

Akinori Hosoyamada; Tetsu Iwata

Paper 2020/1344

Indifferentiability of SKINNY-HASH Internal Functions

Akinori Hosoyamada and Tetsu Iwata

Abstract

We provide a formal proof for the indifferentiability of SKINNY-HASH internal function from a random oracle. SKINNY-HASH is a family of function-based sponge hash functions, and it was selected as one of the second round candidates of the NIST lightweight cryptography competition. Its internal function is constructed from the tweakable block cipher SKINNY. The construction of the internal function is very simple and the designers claim $n$ -bit security, where $n$ is the block length of SKINNY. However, a formal security proof of this claim is not given in the original specification of SKINNY-HASH. In this paper, we formally prove that the internal function of SKINNY-HASH has -bit security, i.e., it is indifferentiable from a random oracle up to queries, substantiating the security claim of the designers.

Note: Minor revision: Some information on related works is added.

Metadata

Available format(s): PDF
Category: Secret-key cryptography
Publication info: Preprint. MINOR revision.
Keywords: provable security sponge construction indifferentiability SKINNY SKINNY-HASH
Contact author(s): akinori hosoyamada bh @ hco ntt co jp
hosoyamada akinori @ nagoya-u jp
tetsu iwata @ nagoya-u jp
History: 2020-11-02: revised; 2020-10-29: received; See all versions
Short URL: https://ia.cr/2020/1344
License: CC BY

BibTeX

@misc{cryptoeprint:2020/1344,
      author = {Akinori Hosoyamada and Tetsu Iwata},
      title = {Indifferentiability of {SKINNY}-{HASH} Internal Functions},
      howpublished = {Cryptology {ePrint} Archive, Paper 2020/1344},
      year = {2020},
      url = {https://eprint.iacr.org/2020/1344}
}