Certificateless strong key-insulated signature

To mitigate the damages of key-exposure, Dodis, Katz, Xu, and Yung, in Eurocrypt 2002, proposed a new paradigm called key-insulated security which provides tolerance against key exposures. Recently many identity-based key insulated signatures schemes have been proposed, however the problem of key escrow is inherent in this setting. To overcome this problem, certificateless public key cryptography was introduced in 2003. In this paper, we extend ID-based key-insulated signatures to certificateless scenarios and propose a certificateless key-insulated signature scheme with secure key-updates. The proposed scheme is strong key-insulated and perfectly key-insulated in the random oracle model.