The 2005 issue of the International Workshop on Practice and Theory in Public Key Cryptography (PKC 2005) was held in Les Diablerets, Switzerland during January 23-26, 2005. It followed a series of successful PKC workshops which started in 1998 in Paci?co Yokohama, Japan. Previous workshops were succ- sively held in Kamakura (Japan), Melbourne (Australia), Cheju Island (South Korea),Paris(France),Miami(USA), andSingapore.Since 2003,PKChasbeen sponsoredbytheInternationalAssociationforCryptologicResearch(IACR).As in previous years, PKC 2005 was one of the major meeting points of worldwide research experts in public-key cryptography. I had the honor to co-chair the workshop together with Jean Monnerat and to head the program committee. Inspired by the fact that the RSA cryptosystem was invented on ski lifts, we decided that the best place for PKC was at a ski resort. Jean Monnerat and I hope that this workshop in a relaxed atmosphere will lead us to 25 more years of research fun. PKC 2005 collected 126 submissions on August 26, 2004. This is a record number. The program committee carried out a thorough review process.In - tal, 413 review reports were written by renowned experts, program committee members as well as external referees. Online discussions led to 313 additional discussionmessagesand 238emails. The reviewprocesswasrun using email and the Webreview software by Wim Moreau and Joris Claessens. Every submitted paperreceivedatleast3reviewreports.Weselected28papersforpublicationon October 28, 2004. Authors were then given a chance to revise their submission over the following two weeks. This proceedings includes all the revised papers.
