Improved Cryptanalysis of Provable Certificateless Generalized Signcryption

Certificateless generalized signcryption adaptively work as certificateless signcryption, signature or encryption scheme having single algorithm for suitable storage-constrained environments. Recently, Zhou et al. proposed a novel Certificates generalized scheme, and proved its ciphertext indistinguishability under adaptive chosen ciphertext attacks (IND-CCA2) using Gap Bi-linear Diffie-Hellman and Computational Diffie-Hellman assumption as well as proved existential unforgeability against chosen message attacks (EUF-CMA) using the Gap Bi-linear Diffie-Hellman and Computational Diffie-Hellman assumption in random oracle model. In this paper, we analyzed Zhou et al. scheme and unfortunately proved IND-CCA2 insecure in encryption and signcryption modes in defined security model. We also present a practical and improved scheme, provable secure in random oracle model.

@article{Waheed2019,
  title     = {Improved Cryptanalysis of Provable Certificateless Generalized Signcryption},
  journal   = {International Journal of Advanced Computer Science and Applications},
  volume    = {10},
  number    = {4},
  year      = {2019},
  publisher = {The Science and Information Organization},
  author    = {Abdul Waheed and Jawaid Iqbal and Nizamud Din and Shahab Ul Islam and Arif Iqbal Umar and Noor Ul Amin},
  doi       = {10.14569/IJACSA.2019.0100475},
  url       = {https://doi.org/10.14569/IJACSA.2019.0100475}
}