Efficient and secure pairing-free certificateless strong key-insulated signature scheme

Abstract

Public Key Cryptosystem (PKC) is playing an important role in providing security services in many applications and hence gained a wide reorganization. The security of this cryptosystem completely relies on the user’s secret key. However, leakage of secret key makes the system insecure. To avoid the damage caused by the leakage of secret key, Key-insulation mechanism was introduced. This technique works with the help of a secure device by updating the secret key in regular time intervals. Certificateless cryptosystem alleviates the heavy certificate management problems in traditional Public Key Infrastructure and eliminates the key escrow problem in Identity based cryptosystem. To integrate the advantages of both certificateless cryptosystem and key insulation technique, certificateless key insulated cryptosystems have been introduced. Recently many certificateless key insulated signature (CLSKIS) schemes have been proposed in literature; however, majority of the CLSKIS schemes are designed in pairing based background, where heavy bilinear pairing operations are involved. This heavy pairing operation causes the schemes to be insignificant in practice. In order to reduce the computational and communication costs and to handle the secret key leakage problems in certificateless signature schemes, we propose a new strong key insulated certificateless signature scheme in pairing free environment. Efficiency analysis confirms that the proposed scheme is more efficient than the existing schemes.