veffChain: Enabling Freshness Authentication of Rich Queries Over Blockchain Databases
Qin Liu, Yu Peng, Ziyi Tang, Hongbo Jiang, Jie Wu, Tian Wang, Tao Peng, Guojun Wang
Abstract
With the wide adoption of blockchains in data-intensive applications, enabling verifiable queries over a blockchain database is urgently required. Aiming at reducing costs, previous solutions embed a small-sized authenticated data structure (ADS) in each block header, so that a user can verify search results without maintaining a full copy of blockchain databases. However, existing studies focus on exact queries with difficulty to guarantee the freshness of search results. In this article, we propose two frameworks, called <inline-formula><tex-math notation="LaTeX">$\mathsf{veffChain}$</tex-math></inline-formula> and <inline-formula><tex-math notation="LaTeX">$\mathsf{veffChain++}$</tex-math></inline-formula> , to realize freshness authentication of rich queries over blockchain databases. Specifically, <inline-formula><tex-math notation="LaTeX">$\mathsf{veffChain}$</tex-math></inline-formula> concerns about verifiable latest- <inline-formula><tex-math notation="LaTeX">$K$</tex-math></inline-formula> exact queries and employs RSA accumulator to generate constant-size ADSs; <inline-formula><tex-math notation="LaTeX">$\mathsf{veffChain++}$</tex-math></inline-formula> integrates RSA accumulator into the Trie tree to further authenticate latest- <inline-formula><tex-math notation="LaTeX">$K$</tex-math></inline-formula> fuzzy queries. For improved scalability, an adaptive keyword splitting (AKS) solution is proposed to enable ADSs to be incrementally updated. Compared with the state-of-the-art work, our frameworks have the following merits: (1) <i>Freshness Guarantee</i> . The user can efficiently retrieve the freshest data from a blockchain database in a verifiable way. (2) <i>Flexibility</i> . The user can specify different query patterns on demand to retrieve data as accurately as possible. The detailed security analysis and extensive experiments validate the practicality of our frameworks.