@misc{cryptoeprint:2013:658,
author = {Pawel Morawiecki and Josef Pieprzyk},
title = {Parallel authenticated encryption with the duplex construction},
howpublished = {Cryptology ePrint Archive, Report 2013/658},
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.