Study of the rate-distortion theory for Shannon cipher system

Research Project

Project/Area Number	06650399
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	情報通信工学
Research Institution	The University of Tokyo
Principal Investigator	YAMAMOTO Hirosuke The University of Tokyo, Department of Mathematical Engineering and Information Physics, Associate Professor, 大学院・工学系研究科, 助教授 (30136212)
Co-Investigator(Kenkyū-buntansha)	ARIMOTO Suguru The University of Tokyo, Department of Mathematical Engineering and Information, 大学院・工学系研究科, 教授 (00029399)
Project Period (FY)	1994 – 1995
Project Status	Completed (Fiscal Year 1995)
Budget Amount *help	¥2,400,000 (Direct Cost: ¥2,400,000) Fiscal Year 1995: ¥800,000 (Direct Cost: ¥800,000) Fiscal Year 1994: ¥1,600,000 (Direct Cost: ¥1,600,000)
Keywords	Shannon Theory / Cryptology / Rate-Distortion theory / Coding theorem / レイト・歪理論
Research Abstract	In this study, the following coding theorems are obtained for the Shannon cipher system. Case 1 (Secret information : discrete, Security level : entropy of secret information conditioned cryptogram) (a) For the case of less-noisy discrete broadcast channel, the achievable region of cryptogram rate R,key rate R_k, security level h, and admissible distortion of regular receiver is determined. (b) For the case of the Gaussian wiretap channel, the achievable region of cryptogram rate R,key rate R_k security level h, and admissible distortion of regular receiver is determined. Case 2 (Secret information : continuous, Security level : attainable minimum distortion of wiretappers) (a) For the case of less-noisy discrete broadcast channel, inner and outer bounds of the achievable region of cryptogram rate R,key rate R_k, security level D,and admissible distortion of regular receiver are derived. (b) For the case of the Gaussian wiretap channel, inner and outer bounds of the achievable region of cryptogram rate R,key rate R_k, security level D,and admissible distortion of regular receiver are derived. Case 3 (Secret information : discrete, Security level : attainable minimum distortion of wiretappers) (a) For the case of noiseless channel, inner and outer bounds of the achievable region of cryptogram rate R,key rate R_k, security level D,and admissible distortion of regular receiver are derived.