## CryptoDB

### Paper: Masking Based Domain Extenders for UOWHFs: Bounds and Constructions

Authors: Palash Sarkar URL: http://eprint.iacr.org/2003/225 Search ePrint Search Google We study the class of masking based domain extenders for UOWHFs. Our first contribution is to show that any correct masking based domain extender for UOWHF which invokes the compression UOWHF $s$ times must use at least $\lceil\log s\rceil$ masks. As a consequence we obtain the optimality of Shoup's algorithm among the class of masking based domain extenders. Our second contribution is to present a new parallel domain extender for UOWHF. The new algorithm obtains an asymptotically optimal speed-up over the sequential algorithm and the key expansion is almost everywhere optimal, i.e., it is optimal for almost all possible number of invocations of the compression UOWHF.
##### BibTeX
@misc{eprint-2003-11938,
title={Masking Based Domain Extenders for UOWHFs: Bounds and Constructions},
booktitle={IACR Eprint archive},
keywords={UOWHF, domain extender, parallel algorithm},
url={http://eprint.iacr.org/2003/225},
note={ palash@isical.ac.in 12464 received 27 Oct 2003, last revised 16 Feb 2004},
author={Palash Sarkar},
year=2003
}