@misc{cryptoeprint:2004:131,
author = {Jung Hee Cheon and Yongdae Kim and Hyo Jin Yoon},
title = {A New ID-based Signature with Batch Verification},
howpublished = {Cryptology ePrint Archive, Report 2004/131},
year = {2004},
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.