Decentralized Broadcast Encryption Schemes with Constant Size Ciphertext and Fast Decryption

Abstract

Broadcast encryption ( BE ) allows a sender to encrypt a message to an arbitrary target set of legitimate users and to prevent non-legitimate users from recovering the broadcast information. BE has numerous practical applications such as satellite geolocation systems, file sharing systems, pay-TV systems, e-Health, social networks, cloud storage systems, etc. This paper presents two new decentralized BE schemes. Decentralization means that there is no single authority responsible for generating secret cryptographic keys for system users. Therefore, the scheme eliminates the concern of having a single point of failure as the central authority could be attacked, become malicious, or become unavailable. Recent attacks have shown that the centralized approach could lead to system malfunctioning or to leaking sensitive information. Another achievement of the proposed BE schemes is their performance characteristics that make them suitable for environments with light-weight clients, such as in Internet-of-Things (IoT) applications. The proposed approach improves the performance over existing decentralized BE schemes by simultaneously achieving constant size ciphertext, constant size secret key and fast decryption.