@misc{cryptoeprint:2008:175,
author = {Kevin D. Bowers and Ari Juels and Alina Oprea},
title = {Proofs of Retrievability: Theory and Implementation },
howpublished = {Cryptology ePrint Archive, Report 2008/175},
year = {2008},
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.