Identity Based Group Encryption
Cloud computing makes it easy for people to share files anywhere and anytime with mobile end devices. There is a privacy issue in such applications even if the files are encrypted. Specially, the public keys or identities of the receivers will be exposed to the cloud server or hackers. Group Encryption GE is designed to achieve anonymity of the receivers. The existing GE schemes are all realized in the public key infrastructure PKI setting, in which complicated certificates management is required to ensure security. It is observed that GE is especially appealing to institutions which usually have their own closed secure user management system. In this paper, we propose a new concept, referred to as identity based group encryption IBGE, which realizes GE in the identity based cryptography setting. In the IBGE, a private key generator PKG designates each user a secret key associated with his identity; and the user can register his identity as a group member to a group manager without leaking his secret key. Then anyone can send confidential messages to the group member without leaking the group member's identity. However, the group manager can trace the receiver if a dispute occurs or the privacy mechanism is abused. Following this model, we propose the first IBGE scheme that is formally proven secure in the standard model. Analysis shows that our scheme is also efficient and practical.
ACISP