No abstract

Performing information retrieval tasks while preserving data confidentiality is a desirable capability when a database is stored on a server maintained by a third-party service provider. This paper addresses the problem of enabling content-based retrieval over encrypted multimedia databases. Search indexes, along with multimedia documents, are first encrypted by the content owner and then stored onto the server. Through jointly applying cryptographic techniques, such as order preserving encryption and randomized hash functions, with image processing and information retrieval techniques, secure indexing schemes are designed to provide both privacy protection and rank-ordered search capability. Retrieval results on an encrypted color image database and security analysis of the secure indexing schemes under different attack models show that data confidentiality can be preserved while retaining very good retrieval performance. This work has promising applications in secure multimedia management.

This paper introduces a new framework for confidentiality preserving rank-ordered search and retrieval over large document collections. The proposed framework not only protects document/query confidentiality against an outside intruder, but also prevents an untrusted data center from learning information about the query and the document collection. We present practical techniques for proper integration of relevance scoring methods and cryptographic techniques, such as order preserving encryption, to protect data collections and indices and provide efficient and accurate search capabilities to securely rank-order documents in response to a query. Experimental results on the W3C collection show that these techniques have comparable performance to conventional search systems designed for non-encrypted data in terms of search accuracy. The proposed methods thus form the first steps to bring together advanced information retrieval and secure search capabilities for a wide range of applications including managing data in government and business operations, enabling scholarly study of sensitive data, and facilitating the document discovery process in litigation.

This paper addresses the problem of image retrieval from an encrypted database, where data confidentiality is preserved both in the storage and retrieval process. The paper focuses on image feature protection techniques which enable similarity comparison among protected features. By utilizing both signal processing and cryptographic techniques, three schemes are investigated and compared, including bitplane randomization, random projection, and randomized unary encoding. Experimental results show that secure image retrieval can achieve comparable retrieval performance to conventional image retrieval techniques without revealing information about image content. This work enriches the area of secure information retrieval and can find applications in secure online services for images and videos.

Abstract-Many applications of wireless sensor networks require precise knowledge of the locations of constituent nodes. In these applications, it is desirable for the nodes to be able to autonomously determine their locations before they start sensing and transmitting data. Most localization algorithms use anchor nodes with known locations to determine the positions of the remaining nodes. However, these existing techniques often fail in hostile environments where some of the nodes may be compromised by adversaries and used to transmit misleading information aimed at preventing accurate localization of the remaining sensors. In this paper, a computationally efficient secure localization algorithm that withstands such attacks is described. The proposed algorithm combines iterative gradient descent with selective pruning of inconsistent measurements to achieve high localization accuracy. Results show that the proposed algorithm utilizes fewer computational resources and achieves an accuracy better than or comparable to that of existing schemes. The proposed secure localization algorithm can also be used in mobile sensor networks, where all nodes are moving, to estimate the relative locations of the nodes without relying on anchor nodes. Simulations demonstrate that the proposed algorithm can find the relative location map of the entire mobile sensor network even when some nodes are compromised and transmit false information.Index Terms-Gradient descent, mobile sensor networks (MSNs), secure localization, wireless sensor networks (WSNs).