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Home | Seminars and Symposia | Past seminars/symposia: Friday, July 6, 2007

DTC Seminar Series

Discrete Logarithm Problems with Auxiliary Inputs


Jung Hee Cheon
Seoul National University

Friday, July 6, 2007
11:00 am

402 Walter Library

DTC Security Seminar

In this talk, we propose an algorithm to solve discrete logarithm problem when some auxiliary inputs are provided. This algorithm reduces by upto 2-30 the complexity of cryptographic schemes based on strong Diffie-Hellman problem. The applications include broadcast encryption schemes, traitor tracing schemes, ID-based encryptions/signatures, short signatures, group signatures. Further this algorithm can be used to recover the secret key more efficiently when the decryption oracle can be accessed to the original ElGamal encryption scheme.



Jung Hee Cheon received his B.S., M.S., and Ph.D. degrees in mathematics from Korea Advanced Institute of Science and Technology (KAIST) in 1991, 1993, and 1997, respectively. For three years from 1997, he worked for Electronics and Telecommunication s Research Institute (ETRI). In 2000 he held postdoc position in Brown university working with J. Silverman. After working as an assistant professor in Information and Communications University (ICU) for two years, he joined Seoul National University (SNU) in 2003. He has published seven papers on number theory journals and twenty four papers on international cryptography conferences including six papers in Crypto and Eurocrypt. He is one of the inventors of braid cryptography and Xedni calculus on elliptic curve discrete logarithms. His research interests include computational number theory, cryptography and information security.