Crypto 2001, the 21st Annual Crypto conference, was sponsored by the Int- national Association for Cryptologic Research (IACR) in cooperation with the IEEE Computer Society Technical Committee on Security and Privacy and the Computer Science Department of the University of California at Santa Barbara. The conference received 156 submissions, of which the program committee selected 34 for presentation; one was later withdrawn. These proceedings contain the revised versions of the 33 submissions that were presented at the conference. These revisions have not been checked for correctness, and the authors bear full responsibility for the contents of their papers. The conference program included two invited lectures. Mark Sherwin spoke on, \Quantum information processing in semiconductors: an experimentalist’s view." Daniel Weitzner spoke on, \Privacy, Authentication & Identity: A recent history of cryptographic struggles for freedom." The conference program also included its perennial \rump session," chaired by Stuart Haber, featuring short, informal talks on late{breaking research news. As I try to account for the hours of my life that ?ew o to oblivion, I realize that most of my time was spent cajoling talented innocents into spending even more time on my behalf. I have accumulated more debts than I can ever hope to repay. As mere statements of thanks are certainly insu cient, consider the rest of this preface my version of Chapter 11.

Crypto 2001, the 21st Annual Crypto conference, was sponsored by the Int- national Association for Cryptologic Research (IACR) in cooperation with the IEEE Computer Society Technical Committee on Security and Privacy and the Computer Science Department of the University of California at Santa Barbara. The conference received 156 submissions, of which the program committee selected 34 for presentation; one was later withdrawn. These proceedings contain the revised versions of the 33 submissions that were presented at the conference. These revisions have not been checked for correctness, and the authors bear full responsibility for the contents of their papers. The conference program included two invited lectures. Mark Sherwin spoke on, \Quantum information processing in semiconductors: an experimentalist’s view." Daniel Weitzner spoke on, \Privacy, Authentication & Identity: A recent history of cryptographic struggles for freedom." The conference program also included its perennial \rump session," chaired by Stuart Haber, featuring short, informal talks on late{breaking research news. As I try to account for the hours of my life that ?ew o to oblivion, I realize that most of my time was spent cajoling talented innocents into spending even more time on my behalf. I have accumulated more debts than I can ever hope to repay. As mere statements of thanks are certainly insu cient, consider the rest of this preface my version of Chapter 11.

CRYPTO is a conference devoted to all aspects of cryptologic research. It is held each year at the University of California at Santa Barbara. Annual meetings on this topic also take place in Europe and are regularly published in this Lecture Notes series under the name of EUROCRYPT. This volume presents the proceedings of the ninth CRYPTO meeting. The papers are organized into sections with the following themes: Why is cryptography harder than it looks?, pseudo-randomness and sequences, cryptanalysis and implementation, signature and authentication, threshold schemes and key management, key distribution and network security, fast computation, odds and ends, zero-knowledge and oblivious transfer, multiparty computation.

EUROCRYPT 2001, the 20th annual Eurocrypt conference, was sponsored by the IACR, the International Association for Cryptologic Research, see http://www. iacr. org/, this year in cooperation with the Austrian Computer - ciety (OCG). The General Chair, Reinhard Posch, was responsible for local or- nization, and registration was handled by the IACR Secretariat at the University of California, Santa Barbara. In addition to the papers contained in these proceedings, we were pleased that the conference program also included a presentation by the 2001 IACR d- tinguished lecturer, Andrew Odlyzko, on “Economics and Cryptography” and an invited talk by Silvio Micali, “Zero Knowledge Has Come of Age. ” Furthermore, there was the rump session for presentations of recent results and other (p- sibly satirical) topics of interest to the crypto community, which Jean-Jacques Quisquater kindly agreed to run. The Program Committee received 155 submissions and selected 33 papers for presentation; one of them was withdrawn by the authors. The review process was therefore a delicate and challenging task for the committee members, and I wish to thank them for all the e?ort they spent on it. Each committee member was responsible for the review of at least 20 submissions, so each paper was carefully evaluated by at least three reviewers, and submissions with a program committee member as a (co-)author by at least six.

The origins of the Asiacrypt series of conferences can be traced back to 1990, when the ?rst Auscrypt conference was held, although the name Asiacrypt was ?rst used for the 1991 conference in Japan. Starting with Asiacrypt 2000, the conference is now one of three annual conferences organized by the Inter- tional Association for Cryptologic Research (IACR). The continuing success of Asiacrypt is in no small part due to the e?orts of the Asiacrypt Steering C- mittee (ASC) and the strong support of the IACR Board of Directors. There were 153 papers submitted to Asiacrypt 2001 and 33 of these were accepted for inclusion in these proceedings. The authors of every paper, whether accepted or not, made a valued contribution to the success of the conference. Sending out rejection noti?cations to so many hard working authors is one of the most unpleasant tasks of the Program Chair. The review process lasted some 10 weeks and consisted of an initial refe- eing phase followed by an extensive discussion period. My heartfelt thanks go to all members of the Program Committee who put in extreme amounts of time to give their expert analysis and opinions on the submissions. All papers were reviewed by at least three committee members; in many cases, particularly for those papers submitted by committee members, additional reviews were obt- ned. Specialist reviews were provided by an army of external reviewers without whom our decisions would have been much more di?cult.