(3) Based on Matrix-AC and private information retrieval protocol, we construct selleck chemicals Tipifarnib a secure additive ranking index (SecARI) that enables the server to efficiently compute the top-ranking snippet over encrypted data while no partial information about the document is leaked, and then we propose the complete construction to realize SecQBP and prove that it is secure under our security model. (4) We propose a high level solution to combine the preview scheme with searchable encryption technique, which greatly improves the user experience.The rest of the paper is organized as follows. Section 2 presents the related work. Section 3 presents the notations and preliminaries. Section 4 presents our proposed additive coding scheme. In Section 5 we formally define the preview scheme and its security model and present the construction in detail.

We present the application in searchable encryption and analyze the performance in Section 6. Section 7 concludes this paper.2. Related Work We categorize the related work into four topics, and each topic is summarized separately.2.1. Query-Biased SnippetQuery-biased snippet refers to a piece of the content in a document that contains the queried keywords. Query-biased snippet generation schemes are widely used in modern search engine. It is also named dynamic summary or keyword-in-context (KWIC) snippet generation. The term was used firstly in [1]. The improvements were introduced in [2�C6]. However, as far as we know, all query-biased schemes are focused on dynamically retrieving snippets from the plaintext.

If the document is encrypted, dynamic scanning becomes impossible. Static preview refers to a snippet summarizing the content in advance, which is always the same regardless of the query. It is generally composed of either a subset of the content or metadata associated with the document. A lightweight static preview scheme over the encrypted data was introduced in [7]. Batimastat For more details, please refer to [8] for a survey of the recent preview schemes.2.2. Searchable EncryptionOur proposed scheme and security model are based on searchable encryption technique. The basic goal of searchable encryption is to enable a user to privately search over encrypted data by keywords. The first scheme was introduced in [9]. Later on, many index-based symmetric searchable encryption schemes were proposed. The first secure index was introduced in [10], and the security model of adaptive chosen keyword attack (IND-CKA) was also introduced. Reference [11] introduced two constructions to realize symmetric searchable encryption: the first is SSE-1 which is nonadaptive and the second is SSE-2 which is adaptive.