Efficient certificateless proxy signature scheme with provable security

In this paper we propose a very efficient and provably secure proxy signature scheme with implicit certificate (called “certificateless proxy signature scheme”), where a receiver does not have to verify a certificate before verifying a signed message, yet only the original signer or the proxy signer who properly registered its public key and identity information is able to sign. Unlike traditional approaches which assume a PKI where the original signer and the proxy signer already hold their public keys and digital certificates, our scheme does not need for each user to have a public key and a certificate, thus we can save the time for verifying the original signer’s and the proxy signer’s certificates in the proxy signature verification phase. Furthermore, we present a formal security model for our scheme under the intractability of the computational Diffie–Hellman problem in the random oracle model.