Cryptology ePrint Archive: BibTeX Citation of Report 2013/805

@misc{cryptoeprint:2013:805,
    author = {Giuseppe Ateniese and Ilario Bonacina and Antonio Faonio and Nicola Galesi},
    title = {Proofs of Space: When Space is of the Essence},
    howpublished = {Cryptology ePrint Archive, Report 2013/805},
    year = {2013},
    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.