無線通信におけるガウス性相関情報に基づく秘密鍵共有の秘密鍵容量: その1: 衛星通信路モデル

Abstract

Information security schemes based on radio propagation property such as secret key agreement and secret data transmission have attracted attention in the current wireless community. For the secret key agreement from common information, a general formula of the secret key capacity is given, but a specific formula of secret key capacity has not present for secret key agreement from Gaussian correlated information, which is typical case in wireless channels. This paper deals with the theoretical analysis on secret key capacity for the satellite communication channel model. The analysis result shows that the upper band of secret key capacity is given with conditional mutual information and that the formula of upper and lower band is expressed as functions of the signal-to-noise power ratio and the noise power ratio of eavesdropper to legitimate user. The analysis result also shows that secret key capacity can approximately be given by conditional mutual information in the case that noise power ratio of eavesdropper to legitimate user is large.