Michael Backes Matteo Maffei Dominique Unruh Zero-Knowledge in the Applied Pi-calculus and Automated Verification of the Direct Anonymous Attestation Protocol. 202-215 2008 IEEE Symposium on Security and Privacy http://doi.ieeecomputersociety.org/10.1109/SP.2008.23 conf/sp/2008 db/conf/sp/sp2008.html#BackesMU08