In a Public Safety (PS) situation, agents may require critical and personally identifiable information. Therefore, not only does context and location-aware information need to be available, but also the privacy of such information should be preserved. Existing solutions do not address such a problem in a PS environment. This paper proposes a framework in which anonymized Personal Information (PI) is accessible to authorized public safety agents under a PS circumstance. In particular, we propose a secure data storage structure along with privacy-preserving mobile search framework, suitable for Public Safety Networks (PSNs). As a result, availability and privacy of PI are achieved simultaneously. However, the design of such a framework encounters substantial challenges, including scalability, reliability of the data, computation and communication and storage efficiency, etc. We leverage Secure Indexing (SI) methods and modify Bloom Filters (BFs) to create a secure data storage structure to store encrypted meta-data. As a result, our construction enables secure and privacy-preserving multi-keyword search capability. In addition, our system scales very well, maintains availability of data, imposes minimum delay, and has affordable storage overhead. We provide extensive security analysis, simulation studies, and performance comparison with the state-of-the-art solutions to demonstrate the efficiency and effectiveness of the proposed approach. To the best of our knowledge, this work is the first to address such issues in the context of PSNs.
Surveying the literature, the works proposed for centralized and mobile healthcare and emergency handling, and search over encrypted data, are the most germane to ours. In such research fields, data availability is achieved in two ways; Centralized Availability ( @math ) and Decentralized Availability ( @math ). In @math , Data Owners (DOs) outsource the encrypted information to one many cloud server(s) to which PSAs should send information retrieval requests, while in @math , in an emergency, DOs broadcast their encrypted PI using smart phones or Personal Digital Assistants (PDAs) to the users in their local proximity or to Health Service Providers (HSPs) to ask for help. The PDA monitors and collects health information using the sensors attached to the patient's body. To achieve data privacy, in addition to data confidentiality, Direct Authorization (DA) or Indirect Authorization (IA) algorithms are utilized. DA methods are usually used in private domains which are comprised of family, personal physician, friends, and neighbours, while IA is applied in public domains that include researchers, healthcare personnel, other doctors, and so forth @cite_6 .
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In cloud computing, clients usually outsource their data to the cloud storage servers to reduce the management costs. While those data may contain sensitive personal information, the cloud servers cannot be fully trusted in protecting them. Encryption is a promising way to protect the confidentiality of the outsourced data, but it also introduces much difficulty to performing effective searches over encrypted information. Most existing works do not support efficient searches with complex query conditions, and care needs to be taken when using them because of the potential privacy leakages about the data owners to the data users or the cloud server. In this paper, using on line Personal Health Record (PHR) as a case study, we first show the necessity of search capability authorization that reduces the privacy exposure resulting from the search results, and establish a scalable framework for Authorized Private Keyword Search (APKS) over encrypted cloud data. We then propose two novel solutions for APKS based on a recent cryptographic primitive, Hierarchical Predicate Encryption (HPE). Our solutions enable efficient multi-dimensional keyword searches with range query, allow delegation and revocation of search capabilities. Moreover, we enhance the query privacy which hides users' query keywords against the server. We implement our scheme on a modern workstation, and experimental results demonstrate its suitability for practical usage.