Certificateless Public Key Encryption Secure against Malicious KGC Attacks in the Standard Model

Abstract

Recently, Au et al. (Au et al. 2007) pointed out a seemingly neglected se- curity concern for certificateless public key encryption (CL-PKE) scheme, where a malicious key generation center (KGC) can compromise the confidentiality of the mes- sages by embedding extra trapdoors in the system parameter. Although some schemes are secure against such an attack, they require random oracles to prove the security. In this paper, we first show that two existing CL-PKE schemes without random ora- cles are not secure against malicious KGC, we then propose the first CL-PKE scheme secure against malicious KGC attack, with proof in the standard model.