Advances in Mathematics of Communications
Quantum-safe identity-based broadcast encryption with provable security from multivariate cryptography
Ramprasad Sarkar, Mriganka Mandal, Sourav Mukhopadhyay
Abstract
Identity-Based Broadcast Encryption ($\textsf{IBBE}$) is a novel concept that can efficiently and securely transmit confidential content to a group of authorized users without the traditional Public-Key Infrastructure ($\textsf{PKI}$). 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 ($\textsf{MPKC}$) with provable security. We are the first to design a quantum-safe $\textsf{IBBE}$ that solely relies on the $\textsf{MPKC}$ framework. Our proposed protocol has achieved $ \mathcal{O}(n) $-size communication bandwidth and $ {n^3}\cdot\mathcal{O}\big(\max\big\{N, {\delta}^4\big\}\big) $-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 ($\textsf{IND-CCA}$) security in the Random Oracle Model ($\textsf{ROM}$) under the hardness of standard Multivariate Quadratic ($\textsf{MQ}$) problem. We emphasize that our system can also be immune against collusion attacks where several users come together to create an illicit decryption box.