Outsourcing encrypted data to the cloud creates a fundamental tension between data privacy and functional searchability. Current Searchable Symmetric Encryption (SSE) solutions frequently have significant limitations, such as excessive metadata leakage, or a lack of fine-grained access control. These issues restrict the scalability of secure searches in real-world applications where multiple clients require different levels of authorization. Our paper proposes MASSE, a dynamic multi-client SSE scheme incorporating attribute-based access control, which expands the OXT framework. With MASSE, clients are restricted sto searching for keywords authorized by their specific attribute sets, and the server remains unaware of the keywords and attributes. MASSE supports practical dynamic updates to documents, and client authorizations, including revocation, without requiring reencryption of the database or indices, or a large number of interactions. We formally prove the security of MASSE, that is, forward and backward privacy under a well-defined leakage profile, and token unforgeability. An experimental evaluation in a database containing 100 keywords, each associated with 150 documents, demonstrates the practical efficiency of MASSE. It takes less than two seconds to generate 10 to 100 keyword queries and 14 seconds to retrieve 50 matching documents. Theoretical results show that MASSE outperforms competing solutions, including OXT, and can be scaled to large encrypted databases. MASSE is also suitable for dynamic cloud deployments. Keywords: Searchable Encryption, SSE, Multi-Client, Attribute Based SSE, Access Control, Revocation, OXT

翻译：将加密数据外包至云端时，数据隐私与功能性可搜索性之间存在根本性矛盾。现有的可搜索对称加密（SSE）方案常存在显著局限，例如过多的元数据泄露，或缺乏细粒度访问控制。这些问题限制了安全搜索在实际应用中的可扩展性，尤其是在多客户端需要不同授权级别的场景下。本文提出MASSE，一种融合基于属性访问控制的动态多客户端SSE方案，该方案扩展了OXT框架。在MASSE中，客户端仅能搜索其特定属性集所授权的关键词，且服务器无法获知关键词与属性信息。MASSE支持对文档及客户端授权（包括撤销）进行实用的动态更新，无需重新加密数据库或索引，也无需大量交互。我们形式化证明了MASSE的安全性，即在明确定义的泄漏模型下满足前向与后向隐私性，以及令牌不可伪造性。在一个包含100个关键词（每个关键词关联150篇文档）的数据库中进行实验评估，结果表明MASSE具有实际效率：生成10至100个关键词查询耗时不足2秒，检索50个匹配文档需14秒。理论分析显示，MASSE性能优于包括OXT在内的现有方案，并能扩展至大型加密数据库。MASSE同样适用于动态云部署环境。关键词：可搜索加密，SSE，多客户端，基于属性的SSE，访问控制，撤销，OXT