These are the proceedings of CHES 2004, the Sixth Workshop on Cryptographic Hardware and Embedded Systems. For the first time, the CHES Workshop has been sponsored by the International Association for Cryptologic Research (IACR).

This year, the number of submissions has reached a new record. One hundred and twenty-five papers were submitted, of which 32 were selected for presentation. Each submitted paper was reviewed by at least 3 members of the program committee. We are very grateful to the program committee for their hard and efficient work in assembling the program. We are also grateful to the 108 external referees who helped in the review process in their area of expertise.

In addition to the submitted contributions, the program includes three invited talks by Neil Gershenfeld (Center for Bits and Atoms, MIT) about "Physical Information Security", by Isaac Chuang (Medialab, MIT) about "Quantum Cryptography", and by Paul Kocher (Cryptography Research) about "Physical Attacks". It also includes a rump session, chaired by Christof Paar, which features informal talks on recent results.

As in the previous years, the workshop focuses on all aspects of cryptographic hardware and embedded system security. We sincerely hope that the CHES Workshop series will remain a premium forum of intellectual exchange in this area.

This workshop would not be possible without the involvement of several persons. In addition to the program committee members and the external referees, we would like to thank Christof Paar and Berk Sunar for their help on local organization. Special thanks also go to Karsten Tellmann for maintaining the web pages and to Julien Brouchier for installing and running the submission and reviewing softwares of K.U.Leuven. Last but not least, we would like to thank all the authors who submitted papers, making the workshop possible, and the authors of accepted papers for their cooperation.

August 2004                               Marc Joye and Jean-Jacques Quisquater
Program co-Chairs, CHES 2004