Efficient verifiable data streaming

In 2012, D. Schr öder and H. Schr öder introduced verifiable data streaming (VDS) that enables a client to append, search, verify, and update the streamed data efficiently. After storing the data with a server, a client issues a query to receive a proof that the data of the client are still correctly stored. Anyone can check the validity of the proof publicly in VDS. However, the length of a secret of a client, the length of a proof, and the complexity of appending an element in the previous VDS schemes are O(logn), where n is the upper bound on the number of elements to be stored. In this paper, we suggest a more efficient VDS scheme. In our scheme, the length of a secret of a client is only O(1), and the length of a proof and the complexity of appending an element are O(logi), where i(≤n) is the index of an element. We also show that our scheme is secure under any collision-resistant hash functions and unforgeable signature schemes without random oracles.