Threshold SKI Protocol for ID-based Cryptosystems

Traditional public key cryptography uses certificates to bind the users with their public keys and are considered the best alternative for key distribution, but requires to have a very involved key management process. Identity based cryptography makes the key management easier but suffers from the key escrow problem and requires secure channel to issue the private keys to the users. Key issuing protocols deal with secret key issuing (SKI) process to overcome the two problems. We present an efficient and secure key issuing protocol which enables the identity based cryptosystems to be more acceptable and applicable in the real world. In the protocol, neither key generating center nor key privacy authority can impersonate the users to obtain the private keys. Performance and security analysis are being carried out for the protocol and is shown that it is efficient and secure against replay, man-in-the-middle and insider attacks.