Cryptanalysis of a certificateless encryption scheme

Certificateless public key cryptography was introduced to address the heavy certificate management in traditional public key cryptography and the key escrow problem in identity-based public key cryptography. Two types of adversaries are considered in certificateless public key cryptography: Type I adversary (outsider) and Type II Adversary (honest-but-curious and/or malicious-but-passive key generation center). A secure certificateless encryption (CLE) scheme must be secure against both types of adversaries. In this paper, we illustrate a recently proposed threshold CLE scheme is insecure against Type I adversaries.