Certificateless deniably authenticated encryption and its application to e-voting system

The concept of deniably authenticated encryption (DAE) is presently significant in cryptography due to its security properties and wide range of application. It achieves deniable authentication and confidentiality in a simultaneous manner. It has merited application in e-voting systems, e-mail systems and confidential online negotiation. Although several DAE schemes have been proposed recently, we point out that those constructions are either weak against masquerading attacks or inherent key escrow problem. As a remedy, we propose a certificateless deniably authenticated encryption (CLDAE) scheme that is provably secure. Typically, we can obtain this goal using the deniable authentication followed by certificateless encryption approach. However, this approach is computationally expensive and complex to design since it is a combination of two cryptographic constructions. In contrast, our CLDAE scheme is a single cryptographic construction but it concurrently accomplishes the requirements of public key encryption and deniable authentication at a relatively lower cost. For instance, our simulation results at 80 bits of security level shows up to be approximately 43.3 and 30.4% respectively faster than two deniable authentication followed by certificateless encryption schemes. Moreover, the communication overhead of our CLDAE scheme is 12.9 and 34.9% lesser than that of those two schemes respectively. Finally, to demonstrate the significance of our CLDAE scheme, we apply it to a real world application such as e-voting system.