These are the proceedings of CT-RSA 2003, the Cryptographers' Track at RSA Conference 2003. The proceedings of CT-RSA 2001 and CT-RSA 2002 were published in Springer-Verlag's Lecture Notes in Computer Science series as LNCS 2020 and LNCS 2271, respectively. The Cryptographers' Track is one of the many parallel tracks of the RSA Conference. With many thousands of participants, the RSA Conference is the largest security and cryptography event of the year. There were 97 submitted contributions this year, of which 26, or 27%, were selected for presentation. The program also included two invited talks by Tom Berson ("Cryptography After the Bubble: How to Make an Impact on the World") and by Adi Shamir ("RSA Shortcuts"). All submissions were reviewed by at least three members of the program committee. I am very grateful to the 21 members of the program committee for their hard and e?cient work in assembling the program. My thanks also go to the 78 external referees who helped in the review process in their area of exp- tise: Gail-Joon Ahn, Toru Akishita, Kazumaro Aoki, Gildas Avoine, Joonsang Baek, Olivier Benoit, Alex Biryukov, Alexandra Boldyreva, Antoon Bosselaers, Emmanuel Bresson, Eric Brier, Brice Canvel, Dario Catalano, Chien Yuan Chen, Donghyeon Cheon, Jung Hee Cheon, Olivier Chevassut, Kilsoo Chun, Mathieu Ciet, Christophe Clavier, Jean-S ́ebastien Coron, Reza Curtmola, Christophe De Canni`ere, Jean-Fran, cois Dhem, Xuhua Ding, Pierre-Alain Fouque, Jacques Fournier, Fabien Germain, Jovan Dj. Goli ́c, Philippe Golle, Louis Granboulan, Jorge Guajardo, D. J.