Information Sharing among Untrustworthy Entities

Most of current technologies that enable secure information sharing assume that entities that share information are mutually trustworthy. However, in recent applications this assumption is not realistic. As applications become sophisticated, information systems are required to share information securely even among untrustworthy entities. This paper discusses two kinds of problems about information sharing among untrustworthy entities, i.e. secure statistical data gathering and anonymous authentication, and proposes their solutions. The former is a problem to calculate statistics while ensuring that raw data are not disclosed to any entity including ones that calculate statistics, and the latter is a problem to authenticate entities while keeping their identities confidential.