@misc{cryptoeprint:2014:506,
author = {Christophe Petit},
title = {Finding Roots in GF(p^n) with the Successive Resultant Algorithm},
howpublished = {Cryptology ePrint Archive, Report 2014/506},
year = {2014},
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.