@misc{cryptoeprint:2011:670,
author = {Peter Schwabe and Bo-Yin Yang and Shang-Yi Yang},
title = {SHA-3 on ARM11 processors},
howpublished = {Cryptology ePrint Archive, Report 2011/670},
year = {2011},
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.