Cryptology ePrint Archive: BibTeX Citation of Report 2012/228

@misc{cryptoeprint:2012:228,
    author = {Marten van Dijk and Ulrich Rührmair},
    title = {Physical Unclonable Functions in Cryptographic Protocols: Security Proofs and Impossibility Results},
    howpublished = {Cryptology ePrint Archive, Report 2012/228},
    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.