On security of a certificateless signcryption scheme

It would be interesting if a signcryption scheme in the standard model could be made certificateless. One of the interesting attempts is due to Liu et al. [Z. Liu, Y. Hu, X. Zhang, H. Ma, Certificateless signcryption scheme in the standard model, Information Sciences 180 (3) (2010) 452–464]. In this paper, we provide a cryptanalysis on this scheme by depicting two kinds of subtle public key replacement attacks against it. Our analysis reveals that it does not meet the basic requirements of confidentiality and non-repudiation.