AHMRE-SCST: Lightweight Anonymous Heterogeneous Multirecipient Encryption With Seamlessly Compatible System Transformation for IoT Devices

Typically, for the system transformation from an original public-key cryptographic system (PKCS) setting to another PKCS setting, the relevant cryptographic schemes must be rewritten for such heterogeneous PKCS settings. Therefore, it is important to ensure that the old entities who have not yet converted to the new PKCS setting can still use the original functionalities of these cryptographic schemes. In the past, numerous anonymous multirecipient encryption (AMRE) schemes based on various PKCS settings have been proposed, but the existing AMRE schemes are only applicable to single PKCS setting and unsuitable for heterogeneous PKCS settings. In this article, we propose a novel and the first anonymous heterogeneous multirecipient encryption (MRE) scheme with the seamlessly compatible system transformation, named as an AHMRE-SCST scheme. The proposed scheme possesses the functionalities of the AMRE schemes while providing the seamlessly compatible system transformation from a public key infrastructure (PKI)-based PKCS (PKI-PKCS) setting to a certificateless (CL)-based PKCS (CL-PKCS) setting. Also, security theorems show that the proposed scheme is secure against the three kinds of attackers in both the PKI-PKCS and the CL-PKCS settings. When compared with the existing AMRE schemes, our scheme has four merits as follows: 1) it is the first AHMRE-SCST scheme; 2) It is well-suitable for the two heterogeneous PKCS settings, namely the PKI-PKCS and the CL-PKCS settings; 3) Its decryption complexity is constant; and 4) By performance analysis, it is well-suitable for the Internet of Things (IoT) devices with the limited resources.