TCC 2009, the 6th Theory of Cryptography Conference, was held in San Fr- cisco, CA, USA, March 15-17, 2009. TCC 2009 was sponsored by the Inter- tional Association for Cryptologic Research (IACR) and was organized in - operation with the Applied Crypto Group at Stanford University. The General Chair of the conference was Dan Boneh. The conference received 109 submissions, of which the Program Comm- tee selected 33 for presentation at the conference. These proceedings consist of revised versions of those 33 papers. The revisions were not reviewed, and the authors bear full responsibility for...