@misc{cryptoeprint:2011:582,
author = {Abdoul Aziz Ciss},
title = {Randomness Extraction in finite fields $\mathbb{F}_{p^{n}}$},
howpublished = {Cryptology ePrint Archive, Report 2011/582},
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.