@misc{cryptoeprint:2013:704,
author = {Mihir Bellare and Viet Tung Hoang},
title = {Adaptive Witness Encryption and Asymmetric Password-based Cryptography},
howpublished = {Cryptology ePrint Archive, Report 2013/704},
year = {2013},
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.