Study of the ratedistortion theory for Shannon cipher system
Project/Area Number  06650399 
Research Category 
GrantinAid for Scientific Research (C).

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)

CoInvestigator(Kenkyūbuntansha) 
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 Fiscal Year 
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 / RateDistortion theory / Coding theorem / シャノン理論 / 暗号 / レート・歪理論 / 符号化定理 / 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 lessnoisy 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 lessnoisy 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.

Report
(4results)
Research Output
(2results)