@misc{cryptoeprint:2008:011,
author = {Ayan Mahalanobis},
title = {A simple generalization of the {E}l{G}amal cryptosystem to non-abelian groups II},
howpublished = {Cryptology ePrint Archive, Report 2008/011},
year = {2008},
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.