System and method for confidentiality-preserving rank-ordered search

Abstract

A confidentiality preserving system and method for performing a rank-ordered search and retrieval of contents of a data collection. The system includes at least one computer system including a search and retrieval algorithm using term frequency and / or similar features for rank-ordering selective contents of the data collection, and enabling secure retrieval of the selective contents based on the rank-order. The search and retrieval algorithm includes a baseline algorithm, a partially server oriented algorithm, and / or a fully server oriented algorithm. The partially and / or fully server oriented algorithms use homomorphic and / or order preserving encryption for enabling search capability from a user other than an owner of the contents of the data collection. The confidentiality preserving method includes using term frequency for rank-ordering selective contents of the data collection, and retrieving the selective contents based on the rank-order.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)[0001]This application claims the benefit of provisional patent application U.S. Ser. No. 61 / 109,291, filed Oct. 29, 2008, which is expressly incorporated herein by reference.GOVERNMENT SUPPORT CLAUSE[0002]This invention was made with government support under H9823005C0425 awarded by NSA. The government has certain rights in the invention.BACKGROUND OF INVENTION[0003]a. Field of Invention[0004]This invention relates to information search and retrieval. In particular, the instant invention relates to a system and method for information search and retrieval in large-scale encrypted databases, with a particular embodiment employing a confidentiality-preserving rank-ordered search.[0005]b. Background Art[0006]In today's information era, efficient and effective search capability of digital collections is essential in information management and knowledge discovery. At the same time, many data collections have to be stored in an encrypted form to li...

AI Technical Summary

Benefits of technology

[0013]The confidentiality preserving rank-ordered search system and method of the invention focuses on secure and efficient rank-ordered search and retrieval over large data collections. The system includes a framework to securely rank-order documents in response to a query, and techniques for extracting the most relevant document(s) from an encrypted data collection. The system and method includes collection of term frequency information for each of the documents in the collection to build indices, as in traditional retrieval systems in plaintext. The system and method further includes securing of these indices that would otherwise reveal important statistical information about the collection to protect against statistical attacks. During the search process, the query terms may be encrypted to prevent the exposure of information to the data center and other intruders, and also confine the searching entity to only make queries within an authorized scope. Utilizing the term frequencies and other document information, schemes are developed herein to securely compute relevance scores of each document, identify the most relevant documents, and reserve the right to screen and release the full content of relevant documents.

[0015]In an exemplary embodiment, the invention provides a confidentiality preserving system for performing a rank-ordered search and retrieval of contents of a data collection. The system may include a computer system including a search and retrieval algorithm using term frequency and / or similar features for rank-ordering selective contents of the data collection, and enabling secure retrieval of the selective contents based on the rank-order.

[0021]The invention also provides a confidentiality preserving method for performing a rank-ordered search and retrieval of contents of a data collection. The method may include using term frequency and / or similar features for rank-ordering selective contents of the data collection, and securely retrieving the selective contents based on the rank-order.

Problems solved by technology

For example, when data storage is outsourced to a third-party data center, system administrators and other personnel involved may not be trusted to have decryption keys and thus have access to the content of the data collections.

When an authorized user remotely accesses the data collection to search and retrieve desired documents, the large size of the collections can often make it infeasible to transfer all encrypted data to the user's side, and then perform decryption and search on the user's trusted computers.

Conventional practices to accommodate such searches on hard-copy collections are extremely time consuming, and are often based on human factors (e.g. have limited memory and bounded by rules of privilege) that cannot all be directly extended to computerized practice.

There has also been minimal effort in addressing secure searching, and such effort has typically been limited to small collections.

This method still incurs a significant increase in storage (for storing the specially encrypted documents) and typically involves a linear time computational complexity with respect to the number of words in the collection.

The aforementioned techniques involve a high computational complexity, and target simple Boolean searches to identify the presence or absence of a term in encrypted text.

Furthermore, the aforementioned techniques cannot be easily extended to more sophisticated relevance-ranked searches over large collections.

The inventors herein have thus recognized the need for balancing privacy and confidentiality with efficiency and accuracy, which pose significant challenges to the design of search schemes for a number of search scenarios and large data collections.

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