Fast Software Encryption is now a 10-year-old workshop on symmetric crypt- raphy, including the design and cryptanalysis of block and stream ciphers, as well as hash functions. The ?rst FSE workshop was held in Cambridge in 1993, followed by Leuven in 1994, Cambridge in 1996, Haifa in 1997, Paris in 1998, Rome in 1999, New York in 2000, Yokohama in 2001, and Leuven in 2002. This Fast Software Encryption workshop, FSE 2003, was held February 24- 26, 2003 in Lund, Sweden. The workshop was sponsored by IACR (International Association for Cryptologic Research) and organized by the General Chair, Ben Smeets, in cooperation with the Department of Information Technology, Lund University. Thisyearatotalof71papersweresubmittedtoFSE2003.Afteratwo-month reviewing process, 27 papers were accepted for presentation at the workshop. In addition, we were fortunate to have in the program an invited talk by James L. Massey. The selection of papers was di?cult and challenging work. Each submission was refereed by at least three reviewers. I would like to thank the program c- mittee members, who all did an excellent job. In addition, I gratefully ackno- edge the help of a number of colleagues who provided reviews for the program committee. They are: Kazumaro Aoki, Alex Biryukov, Christophe De Cannì ere, Nicolas Courtois, Jean-Charles Fau&ggrave; ere, Rob Johnson, Pascal Junod, Joseph Lano, Marine Minier, Elisabeth Oswald, H? avard Raddum, and Markku-Juhani O. Saarinen.