Abstract: Distributed storage is an efficient means for massive data storage. However, the key distribution and update are big challenges for such multi-user network environments. In traditional methods, key distribution and update are controlled by the key distribution center (KDC). The increases users inevitably increase the KDC’s workload. In this paper, a sharing group based cyclic key update scheme (CKUS) is proposed, which makes use of the cyclic characteristic of Chebyshev polynomials and the key management feature of logical key hierarchy (LKH). The special feature of CKUS is that key updating and transmitting do not resort to the public and private keys, but are only multicast by the file owner directly. Thus, file sharers only use local computations, thus increasing computational efficiency. At the same time, the scheme takes advantage of the Chebyshev polynomial’s cyclic characteristic, which make each file sharers update its key self-adaptively, reduce network traffic of key update effectively, and reduces the keys storage requirements of the user nodes.

Key words: chebyshev polynomial, logical key hierarchy (LKH), distributed secure storage, key update