QUANTUM-SAFE IDENTITY-BASED BROADCAST ENCRYPTION WITH PROVABLE SECURITY FROM MULTIVARIATE CRYPTOGRAPHY

Identity-Based Broadcast Encryption (IBBE) is a novel concept that can efficiently and securely transmit confidential content to a group of authorized users without the traditional Public-Key Infrastructure (PKI). After carefully exploring these areas, we have observed that none of the existing works have adopted the quantum-attack resistant cryptographic machinery Multivariate Public-Key Cryptography (MPKC) with provable security. We are the first to design a quantum-safe IBBE that solely relies on the MPKC framework. Our proposed protocol has achieved O(n)-size communication bandwidth and n(3) . O( max {N, delta(4)})-size overhead storage without any security breach. Here, n is the number of variables for each multivariate polynomial, N represents the total number of system users, and delta denotes a positive fixed-length. More positively, our design has achieved the adaptive INDistinguishable Chosen-Ciphertext Attack (IND-CCA) security in the Random Oracle Model (ROM) under the hardness of standard Multivariate Quadratic (MQ) problem. We emphasize that our system can also be immune against collusion attacks where several users come together to create an illicit decryption box.