A Hybrid Signcryption Scheme with Leakage-resilience Resistant to Side-channel Attacks*

In public-key cryptography (PKC), a signcryption (SC) scheme is a significant primitive by combining both signature and encryption functionalities in one scheme while reducing computing time. Most SC schemes are based on single PKC setting, such as public-key infrastructure PKC (PKI-PKC), identity-based PKC (ID-PKC), certificate-based PKC (CB-PKC), and certificateless PKC (CL-PKC). For providing practical usage, numerous hybrid SC (HSC) schemes were also presented to suit for the sense that a sender and a recipient belong to different PKC settings (i.e., heterogeneous PKC settings). Recently, side-channel attacks have been realized to endanger the existing SC and HSC schemes. Indeed, the research of leakage-resilient cryptography resistant to side-channel attacks have attracted the attention of researchers. Indeed, several SC schemes with leakage resilience (SC-LR) based on single PKC setting have been proposed. However, little research focuses on HSC scheme with leakage-resilience (HSC-LR). Therefore, this paper aims to design the first HSC-LR from senders under a CB-PKC setting to recipients under a PKI-PKC setting, called as the HSC-LR-CBPKI scheme. We formally define a new framework and two security games of the HSC-LR-CBPKI scheme. Two security theorems are proved that the HSC-LR-CBPKI scheme possesses both signature and encryption functionalities (including unforgeability and confidentiality) under side-channel attacks. Finally, the proposed scheme is very efficient by performance analysis.