摘要：

可搜索加密技术以提取出的关键词作为索引, 在文档群中对特定文档进行搜索。现有的可搜索加密方案存在消耗随关键词数量增多而显著增加以及多用户索引不能碰撞的问题。针对现有方案的局限性, 提出一种物联网(IoT)场景中多用户多关键词的可搜索加密方案。基于布隆过滤器的特性, 使用内存消耗较小的向量作为索引对文档群进行分组, 在允许索引碰撞的同时提高可搜索加密的效率。利用由加密关键词生成的验证密文对陷门中是否包含本文档所含关键词进行验证, 从而使用户能在共用索引的文档中找到匹配的文档。基于离散对数问题及Diffle-Hellman问题的困难性, 该方案在各阶段生成密文所需的计算次数较少。理论分析和实验结果表明, 该方案具有可用性和安全性, 且通信开销相较对比方案更小。

关键词: 可搜索加密算法, 多关键词加密算法, 布隆过滤器, Diffle-Hellman假设, 离散对数问题

Abstract:

Searchable encryption technology utilizes extracted keywords as indexes to search for specific documents within a document collection. However, existing searchable encryption schemes suffer from the issues of significantly increased resource consumption with an increased number of keywords and the inability to allow index collisions in multi-user scenarios. To address the limitations of the current schemes, a searchable encryption scheme for multi-user and multi-keyword scenarios in Internet of Things (IoT) environments is proposed. Leveraging the characteristics of Bloom filters, a memory-efficient vector is employed as an index for grouping document collections, thereby enhancing the efficiency of searchable encryption while permitting index collisions. A verification ciphertext generated from encrypted keywords is used to verify whether the trapdoor contains the keywords present in a document, thereby enabling users to locate matching documents within the shared-index document collection. Based on the discrete logarithm's hardness and the Diffie-Hellman problems, the proposed scheme requires fewer computational operations for ciphertext generation at each stage. Theoretical analysis and experimental results demonstrate that the scheme is both feasible and secure, with reduced communication overhead when compared with alternative approaches.

Key words: searchable encryption algorithm, multi-keyword encryption algorithm, Bloom filter, Diffle-Hellman assumption, discrete logarithm problem