@misc{cryptoeprint:2012:029,
author = {Yannick Seurin},
title = {On the Exact Security of Schnorr-Type Signatures in the Random Oracle Model},
howpublished = {Cryptology ePrint Archive, Report 2012/029},
year = {2012},
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.