A pairing-free and provably secure certificateless signature scheme

Certificateless Signature (CLS) scheme is a notable cryptographic technique for solving the key escrow problem in identity-based cryptosystem (IBC). In the CLS, the private key is computed collectively by both the key generation center (KGC) and the signer which ensures that no vindictive KGC masquerades the actual signer. Recently, a number of CLS schemes have been proposed using bilinear pairing and show their immunity under standard security model. It is well known that one such pairing operation requires significantly more computational cost than the other cryptographic operations. In this paper, we propose a new CLS scheme using elliptic curve cryptography (ECC), which does not require bilinear pairing operation. Our CLS scheme is analyzed formally and found to be provably secure against both the Type-I and Type-II attacks based on the intractability of elliptic curve discrete logarithm problem (ECDLP) under the random oracle model. Performance evaluation demonstrates that the proposed CLS scheme outperforms than other competitive CLS schemes.