@misc{cryptoeprint:2013:109,
author = {Charanjit S. Jutla and Arnab Roy},
title = {Shorter Quasi-Adaptive NIZK Proofs for Linear Subspaces},
howpublished = {Cryptology ePrint Archive, Report 2013/109},
year = {2013},
note = {\url{http://eprint.iacr.org/}},
}
You will need the url.sty package (comes with most LaTeX installations) for the last line. Otherwise, remove the \url command.