Date Added: Jul 2011
Practical implementations of identity based cryptosystems are faced to key escrow problem, which is not always a good property in many realistic scenarios. Thus, efficient key issuing protocols are needed to generate and deliver user's private keys in secure manner without leakage. Three major approaches exist in the literature, the authors are interested in two of them. The first one suggested the distribution of the master secret key over multiple authorities. The second approach, concerned about user privacy, and proposed to generate and deliver user's private keys in an anonymous manner. Each one of the above approaches has its own drawbacks and key escrow problem is steal an issue in identity-based systems.