Cryptology ePrint Archive: BibTeX Citation of Report 2012/503

@misc{cryptoeprint:2012:503,
    author = {Alex Escala and Javier Herranz and Benoit Libert and Carla Rafols},
    title = {Hierarchical Identity-Based (Lossy) Trapdoor Functions},
    howpublished = {Cryptology ePrint Archive, Report 2012/503},
    year = {2012},
    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.