International Association
for Cryptologic Research

This paper suggests and explores the use of UCE security for the task of

turning VIL-ROM schemes into FIL-ROM ones. The benefits we offer over

indifferentiability, the current leading method for this task, are the ability

to handle multi-stage games and greater efficiency. The paradigm consists of

(1) Showing that a VIL UCE function can instantiate the VIL RO in the scheme,

and (2) Constructing the VIL UCE function given a FIL random oracle. The main

technical contributions of the paper are domain extension transforms that

implement the second step. Leveraging known results for the first step we

automatically obtain FIL-ROM constructions for several primitives whose

security notions are underlain by multi-stage games. Our first domain extender

exploits indifferentiability, showing that although the latter does not work

directly for multi-stage games it can be used indirectly, through UCE, as a

tool for this end. Our second domain extender targets performance. It is

parallelizable and shown through implementation to provide significant

performance gains over indifferentiable domain extenders.