@misc{cryptoeprint:2010:476,
author = {Carlo Blundo and Vincenzo Iovino and Giuseppe Persiano},
title = {Predicate Encryption with Partial Public Keys},
howpublished = {Cryptology ePrint Archive, Report 2010/476},
year = {2010},
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.