Application Authentication System with Efficiently Updatable Signature

Abstract

SUMMARYBroadcasting and communications networks can be used together to offer hybrid broadcasting services that incorporate a variety of personalized information from communications networks in TV programs. To enable these services, many different applications have to be run on a user terminal, and it is necessary to establish an environment where any service provider can create applications and distribute them to users. The danger is that malicious service providers might distribute applications which may cause user terminals to take undesirable actions. To prevent such applications from being distributed, we propose an application authentication protocol for hybrid broadcasting and communications services. Concretely, we modify a key-insulated signature scheme and apply it to this protocol. In the protocol, a broadcaster distributes a distinct signing key to each service provider that the broadcaster trusts. As a result, users can verify that an application is reliable. If a signed application causes an undesirable action, a broadcaster can revoke the privileges and permissions of the service provider. In addition, the broadcaster can update the signing key. That is, our protocol is secure against leakage of the signing key by the broadcaster and service providers. Moreover, a user terminal uses only one verification key for verifying a signature, so the memory needed for storing the verification key in the user terminal is very small. With our protocol, users can securely receive hybrid services from broadcasting and communications networks. key words: hybrid services through broadcasting and communications networks, application authentication, ID-based signature, key-insulated signature