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Home | Seminars and Symposia | Past seminars/symposia: Wednesday, February 19, 2003

DTC Seminar Series

Observations on ID-Based Cryptography and a Simple ID-Based RSA Variant


Gene Tsudik
University of California at Irvine

Wednesday, February 19, 2003
1:00 pm

402 Walter Library

Identity-based public key encryption facilitates easy introduction of public key cryptography by allowing an entity's public key to be derived from an arbitrary identification value, such as name or email address. The main practical benefit of identity-based cryptography is in greatly reducing the need for, and reliance on, public key certificates. Although some interesting identity-based techniques have been developed in the past, none are compatible with popular public key encryption algorithms. This limits the utility of identity-based cryptography as a transitional step to full-blown public key cryptography. Furthermore, it is fundamentally difficult to reconcile fine-grained revocation with identity-based cryptography. Mediated RSA (mRSA) is a simple and practical method of splitting a RSA private key between the user and a Security Mediator SEM. Neither the user nor the SEM can cheat one another since each cryptographic operation (signature or decryption) involves both parties. mRSA allows fast and fine-grained control of users' security privileges. However, mRSA still relies on conventional public key certificates to store and communicate public keys. In this talk, we present IB-mRSA, a simple variant of mRSA that combines identity-based and mediated cryptography. IB-mRSA is as secure as standard RSA; moreover it is simple, practical, and compatible with current public key infrastructures.


Dr. Gene Tsudik is an Associate Professor in the Information and Computer Science Department at University of California in Irvine. He has been active in the area of internetworking, network security and applied cryptography since 1987. He received his Ph.D. in Computer Science from the University of Southern California in 1991 for his work on access control in internetworks. Dr. Tsudik then moved on to IBM Research (1991-1996), and then USC Information Science Institute (1996-2000). Since 2000, he has been a faculty member at UC Irvine ICS Department. Over the years, his research has included: internetwork routing, firewalls, authentication, mobile network security, secure e-commerce, anonymity, secure group communication, digital signatures, key management, ad hoc network routing, and, more recently, database privacy and secure storage. Dr. Tsudik has over 60 referenced publications and 7 patents.