Key-Insulated Signcryption

Signcryption is a public key cryptographic technique that is particularly suited for mobile communications thanks to its light computational and communication overhead. The wide spread use of signcryption in a mobile computing environment, however, is accompanied by an increased risk of private key exposure. This paper addresses the issue of key exposure by proposing a key-insulated signcryption technique. We define a security model for key-insulated signcryption and prove that the keyinsulated signcryption technique is provably secure in the security model.