A Novel Elliptic Curve Based Multi-Key Encryption Method for Multicasting Single Content with Access Control

Abstract

The most remarkable invention in the history of cryptography is the invention of public key encryption in the 1970s. It enables users to have a single encryption on a pair of two unique keys. As a result, the way of delivering many security services has changed drastically. Moreover, it introduced new features such as non-repudiation to the cryptographic world. However, in this paper, we present a novel elliptic curve based multi key encryption method to facilitate a single encryption for multiple users where the resulting encrypted content can be multicast to them with access control. Initially, we establish an elliptic curve based public key infrastructure to cover the whole user space. Then the sender can select multiple recipients using their public keys with the desired access levels and generate a unique polynomial for that using the Lagrange polynomial interpolation. Next, the content is encrypted using the generated polynomial and multicast it to the recipients. Finally, the recipient can use their private key together with the polynomial to decrypt the received content. Encryption is robust because the elliptic curve cryptography is stronger than the present RSA encryption. Moreover, it is more suitable for mobile devices due to small key sizes. However, the cryptographic libraries have to be improved and optimized in order to make it practical. Further, the applications like email clients, media players, document viewers have to be enhanced to integrate this cryptographic mechanism as an add-on.