A lightweight group key management scheme with constant rekeying cost and public bulletin size
Payal Sharma, B. Purushothama · Information Security Journal A Global Perspective · 2023
Several group key management schemes have focused either on meeting security goals or efficiency. However, only a few works exist that address the issue of handling offline users. Trivially, existing schemes need to store all intermediate rekeying messages (for every join and leave operation) onto a public bulletin making them storage inefficient and key derivation costly. This article focuses on the challenges of making the group key management scheme lightweight and efficiently managing offline users. Toward this, we have proposed a group key management scheme based on binary key tree and ex-or operations. The proposed scheme, satisfying forward and backward secrecy requirements, has a constant rekeying cost, and users need to store only one secret key. The proposed scheme maintains the public bulletin board, which keeps rekeying information so that a user who went offline and missed rekeying operations gets the latest group key by using current rekeying messages. In the proposed scheme, the public bulletin is constant with the size of O(n), independent of the number of rekeying operations. The proposed scheme is compared with the existing schemes and is found to be efficient and handles offline users more efficiently than other existing schemes.