Cryptology ePrint Archive: Report 2011/652

Security Enhancement of the Vortex Family of Hash Functions

Shay Gueron and Michael Kounavis

Abstract: Vortex is a new family of one-way hash functions which has been submitted to the NIST SHA-3 competition. Its design is based on using the Rijndael block cipher round as a building block, and using a multiplication-based merging function to support fast mixing in a small number of steps. Vortex is designed to be a fast hash function, when running on a processor that has AES acceleration and has a proven collision resistance [2]. Several attacks on Vortex have been recently published [3, 4, 5, 6] exploiting some structural properties of its design, as presented in the version submitted to the SHA-3 competition. These are mainly ¯rst and second preimage attacks with time complexity below the ideal, as well as attempts to distinguish the Vortex output from random. In this paper we study the root-cause of the attacks and propose few amendments to the Vortex structure, which eliminate the attacks without a®ecting its collision resistance and performance.

Category / Keywords:

Date: received 2 Dec 2011

Contact author: michael e kounavis at intel com

Available format(s): PDF | BibTeX Citation

Version: 20111209:204902 (All versions of this report)

Short URL: ia.cr/2011/652

Discussion forum: Show discussion | Start new discussion