Secure cloud storage offers encrypted databases outsourcing service for resource-constrained clients, containing numerous tables with certain relations. Searchable symmetric encryption enables a client to search over its encrypted database on the cloud, while rarely considering queries over joins of tables. Join Cross-Tags (JXT) protocol (ASIACRYPT 2022) is thence presented that enables conjunctive queries over joins of tables, while neglecting arbitrary Boolean queries with disjunctive and conjunctive normal forms (DNF/CNF) in TWINSSE (PETS 2023). However, trivially combining JXT and TWINSSE for arbitrary DNF/CNF boolean queries over joins of tables seems infeasible due to: (i) no support for dis/conjunctive query with the same meta-keyword; (ii) returning inaccurate search results; (iii) incurring costly storage overhead. Therefore, we introduce TNT-QJ, a practical TwiN cross-Tag protocol for arbitrary boolean Query-Join over multi-tables. The result is technically obtained from revisiting TWINSSE’s framework via using s-term (the least frequent keyword) for the relation between a keyword and its meta-keyword, and non-trivially combined with JXT’s query-join approach for introducing a connective attributed in encryption tuples. In addition, we present a semi-full multi-fork searchable tree to store keyword information and reveal keyword containment relations, where the storage consumption is reduced from $\mathcal {O}(n^{3})$ to $\mathcal {O}(n^{2})$ . Finally, to clarify practical performance, we conduct extensive experiments on JXT and TNT-QJ using an open database in the HUAWEI cloud. Besides enabling disjunctive queries over joins of tables, TNT-QJ also runs $1.2\times $ faster for conjunctive queries than JXT (with #keywords=2), which confirms rich features and practical efficiency.

中文翻译：

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云存储中任意布尔查询连接的实用可搜索对称加密


Secure Cloud Storage 为资源受限的客户提供加密数据库外包服务，包含大量具有一定关系的表。可搜索对称加密使客户端能够在云上搜索其加密数据库，同时很少考虑对表联接的查询。连接交叉标签 （JXT） 协议 （ASIACRYPT 2022） 随后提出，该协议支持对表的连接进行联合查询，同时忽略 TWINSSE （PETS 2023） 中具有析取和连接范式 （DNF/CNF） 的任意布尔查询。但是，将 JXT 和 TWINSSE 轻松组合用于表连接上的任意 DNF/CNF 布尔查询似乎不可行，因为：（i） 不支持具有相同元关键字的 dis/conjunctive 查询;（ii） 返回不准确的搜索结果;（iii） 产生昂贵的存储开销。因此，我们引入了 TNT-QJ，这是一种实用的 TwiN 跨标签协议，用于多表的任意布尔 Query-Join。从技术上讲，结果是通过使用 s-term（最不常见的关键字）来表示关键字与其元关键字之间的关系，并且与 JXT 的查询连接方法相结合，在加密元组中引入连接属性，从而获得结果。此外，我们提出了一个半完全的多分叉可搜索树来存储关键字信息并揭示关键字包含关系，其中存储消耗从 $\mathcal {O}（n^{3}）$ 减少到 $\mathcal {O}（n^{2}）$ 。最后，为了明确实际性能，我们使用华为云中的开放数据库对 JXT 和 TNT-QJ 进行了广泛的实验。除了支持对表联接的析取查询外，TNT-QJ 还运行 1 USD。联合查询的速度比 JXT 快 2 倍 $（#keywords=2），这证实了丰富的功能和实际效率。