Exposure of secret keys can be the most devastating attack on a signature scheme since such that security is entirely lost. In a certificated based environment, the certification revocation list (CRL) can be used to minimize the damage caused by key exposure. In an identity based environment however, key exposure may means that the corresponding entity of the exposed key cannot use his identity information as his public key any more, and is in fact removed from the identity based system. In last few years the notion of and implementations of key insulated cryptosystems have been suggested for protecting the security of cryptosystems. In this work, we apply the method of key insulation to identity based signature, and solve the key exposure problem existing in the identity based schemes. We start by developing the formal model for identity based key insulated signature. We then use the fact to construct a identity based key insulated signature scheme.
['Yuan Zhou', 'Zhenfu Cao', 'Zhenchuan Chai']
Identity based key insulated signature