Group‐oriented encryption for dynamic groups with constant rekeying cost

Abstract

AbstractIn group‐oriented encryption, a sender encrypts a message and sends it to a set of users, which form a group. Encryption is carried out using the group's public key. Only the legitimate group users are capable of decrypting the ciphertext using their individual private keys. Existing literature in group‐oriented encryption schemes considers only static groups in secure group communication. Extension of the existing schemes to support dynamic groups results in the one‐affects‐all problem. We propose a group‐oriented encryption scheme which is capable of handling dynamic groups in secure group communication. In the proposed scheme, we consider groups which are dynamic in nature and involve joining and leaving of members thereby giving rise to the problem of forward and backward secrecy for which group public key needs to be changed. In the proposed scheme, updating the group public key does not affect the group users, and they are not required to update any of their secret key components. The group members can continue their operations with the same secret keys which they are possessing since the time they joined the group. Also, size of the secret key at users, the public key and the ciphertext, remains constant. Copyright © 2016 John Wiley & Sons, Ltd.