Privacy Preserving Keyword Search over Encrypted Cloud Data

Cloud computing enables the organizations to outsource their data by providing a service model called infrastructure as a service (IaaS). In a public cloud the infrastructure is owned and managed by a cloud service provider and is located in the provider’s control. To protect the privacy of sensitive data, documents have to be encrypted before outsourcing. When the number of encrypted documents increases exponentially, the search service and retrieval becomes critical. The process of retrieving the files containing the queried keyword further incurs unnecessary network traffic, which is absolutely undesirable in pay-as-you-use cloud paradigm. In this paper, a search scheme that provides both privacy protection and rank-ordered search capability with less overhead has been proposed. Search indexes and documents are first encrypted by the data owner and then stored onto the cloud server. Retrieval results on an encrypted data and security analysis under different attack models show that data privacy can be preserved while retaining very good retrieval performance.