Certificateless public key encryption made practical
Viet Cuong Trinh · 2017
To deal with the problem of large certificate in Public Key Infrastructure, several techniques have been introduced such as Identity-based cryptography, Implicit certificate, Password-based cryptography and recently Certificateless cryptography at Asiacrypt'03. In a certificateless system, only user with her full private key can decrypt the ciphertext while the authority with her master key cannot. Moreover, there is no need to use the certificate to certify the public key of user. Certificateless public key encryption schemes in the standard model have been proposed in many works. In this paper, we continue this line of research by proposing a new one. When comparing with other certificateless public key encryption schemes in the standard model, our scheme is the best one to date in term of efficiency. However, our scheme only achieves a weak level of security that is the weak selective chosen plaintext Type I adversary under the well-known q-BDHI assumption, and the selective chosen plaintext Type II adversary under a new simple static assumption.