@misc{cryptoeprint:2015:072,
author = {Olivier Blazy and Céline Chevalier and Damien Vergnaud},
title = {Non-Interactive Zero-Knowledge Proofs of Non-Membership},
howpublished = {Cryptology ePrint Archive, Report 2015/072},
year = {2015},
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.