Moreover, we investigate the propagation of the weak stand-alone security notion through the existing security hierarchy, from stand-alone to universal composability. Our main achievement in this direction is a separation result between two variants of the UC security definition: 1-bit specialized simulator UC security and specialized simulator UC security. This solves an open question from [Lindell03] and comes in contrast with the well known equivalence result between 1-bit UC security and UC security. We also show that weak security under 1-bounded concurrent general composition is equivalent to 1-bit specialized simulator UC security. As a consequence, we obtain that the notion of weak stand-alone security and the notion of stand-alone security are not equivalent.
Category / Keywords: security models; UC security; time-lock puzzles; game theory Date: received 1 Jul 2011, last revised 10 May 2012 Contact author: ociobota at mpi-inf mpg de Available formats: PDF | BibTeX Citation Note: Minor style and other corrections. Version: 20120510:112552 (All versions of this report) Discussion forum: Show discussion | Start new discussion