@misc{cryptoeprint:2013:773,
author = {Markku-Juhani O. Saarinen},
title = {CBEAM: Efficient Authenticated Encryption from Feebly One-Way $\phi$ Functions},
howpublished = {Cryptology ePrint Archive, Report 2013/773},
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.