@misc{cryptoeprint:2011:156,
author = {Madeline González Muñiz and Peeter Laud},
title = {Strong Forward Security in Identity-Based Signcryption},
howpublished = {Cryptology ePrint Archive, Report 2011/156},
year = {2011},
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.