Non-repudiation of service agreement (non-repudiation)

摘要

The present invention relates to a non-repudiation efficient service agreement between the user in a communication system (10) and service providers (20) in general. (30) is introduced party reliable additional called so-called service agreement manager (30) is shared with (10) the user terminal (K _i) secret service agreement manager, the present invention, the service provider (20) is based on the idea that the trust relationship between (30) the service agreement manager. Furthermore, based on (14/34) method repudiation proposed by the present invention is validation service agreement user signature service agreements related information, encryption of the information based on a shared secret key (K _i) I want to generate the information. Then, it is transferred service provider (20), verification information of user signature to allow verification of the service agreement based on the trust relationship between service providers (20) and the service agreement manager (30) and (26/36) to.