@misc{cryptoeprint:2011:559,
author = {Eike Kiltz and Adam O'Neill and Adam Smith},
title = {Instantiability of RSA-OAEP under Chosen-Plaintext Attack},
howpublished = {Cryptology ePrint Archive, Report 2011/559},
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.