A novel way of issuing multiple private keys in ID-based Cryptosystems

Abstract

In this paper, we propose a new efficient model for issuing multiple private keys in IBC (Identity-Based Cryptosystem). In our model, the private key of a user is divided into two components: LTK (Long-Term Key) and STK (Short-Term Key). Both are issued separately by different parties. The LTK is issued in a threshold manner by KPAs (Key Privacy Agency). In contrast, the STK is issued by a single authority called KGC (Key Generation Center). A user can efficiently obtain a new private key containing the same identity information by contacting only the KGC and obtaining a new STK. We also give a security proof of the key issuing model and present a new IBE (Identity-Based Encryption) scheme based on our key issuing model. © 2007 IEEE.