An efficient certificateless public key encryption scheme with authorized equality test in healthcare environments

Abstract The challenges confronting the privacy of outsourcing medical data have become a significant concern for patients and healthcare providers. The encryption of this sensitive data before outsourcing to the healthcare server present an effective solution for protection. However, searching on different ciphertexts while protecting the privacy of data remains a research challenge. Indeed, most of the existing schemes are inefficient, particularly for deployment on mobile devices due to limited resources (e.g. computing power, battery lifetime, and storage capacity). In this paper, we propose a CertificateLess Public-Key Encryption with Authorized Equality Test (CLPKE-AET) scheme. With the CLPKE-AET scheme, an authorized cloud server is permitted to check the equivalence of two different ciphertexts consisting of the same messages. Moreover, We provide four types of authorizations, base on which an authorized user can directly search on different user’s ciphertext using different methods while enhancing the privacy of the user’s data. We present our construction from bilinear pairing and demonstrate its security under modified Bilinear Diffie-Hellman (mBDHI) assumption in the Random Oracle Model (ROM). Finally, compared with other’s similar schemes, the performance analysis shows that our CLPKE-AET scheme is practical and more suitable for healthcare environments.