@misc{cryptoeprint:2004:064,
author = {Ratna Dutta and Rana Barua and Palash Sarkar},
title = {Pairing-Based Cryptographic Protocols : A Survey},
howpublished = {Cryptology ePrint Archive, Report 2004/064},
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.