MBP: Multi-channel broadcast proxy re-encryption for cloud-based IoT devices

The broadcast proxy re-encryption methods extend traditional proxy re-encryption mechanisms, where a single user shares the cloud data with multiple receivers. When the sender has different data to share with different sets of users, the existing broadcast proxy re-encryption schemes allow him/her to calculate distinct re-encryption keys for different groups in terms of additional computation time and overhead. To overcome these issues, we propose a scheme, named MBP, in IoT application scenario that allows the sender to calculate a single re-encryption key for all the groups of users, i.e., IoT devices. We use the multi-channel broadcast encryption concept in the broadcast proxy re-encryption method, so as single re-encryption key calculation and single re-encryption are done for different groups of IoT devices. It reduces the size of the security elements. However, it increases the computation time of the receiver IoT devices at the time of decryption of both the ciphertexts. To address this issue, we use the Rubinstein-Stahl bargaining game approach. MBP is secure under a selective group chosen-ciphertext attack using the random oracle model. The implementation of MBP shows that it reduces the communication overhead from the data owner to the cloud server and from the cloud server to the receiver than existing algorithms.