EURASIP Journal on Information Security Signal Processing in the Encrypted Domain Guest Editors: Alessandro Piva and Stefan Katzenbeisser Signal Processing in the Encrypted Domain EURASIP Journal on Information Security Signal Processing in the Encrypted Domain Guest Editors: Alessandro Piva and Stefan Katzenbeisser Copyright © 2007 Hindawi Publishing Corporation. All rights reserved. This is a special issue published in volume 2007 of “EURASIP Journal on Information Security.” All articles are open access articles distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Editor-in-Chief Mauro Barni, University of Siena, Siena, Italy Associate Editors JeffreyA.Bloom,USA D. Kirovski, USA Hans Georg Schaathun, UK G. Doerr,¨ UK Deepa Kundur, USA Martin Steinebach, Germany Jean-Luc Dugelay, France E. Magli, Italy Q. Sun, Singapore T. Furon, France Kivanc Mihcak, Turkey W. Trappe, USA Miroslav Goljan, USA Lawrence O’Gorman, USA C. Vielhauer, Germany S. Katzenbeisser, The Netherlands Fernando Perez-Gonz´ alez,´ Spain S. Voloshynovskiy, Switzerland Hyoung Joong Kim, Korea A. Piva, Italy Andreas Westfeld, Germany Contents Signal Processing in the Encrypted Domain, Alessandro Piva and Stefan Katzenbeisser Volume 2007, Article ID 82790, 1 page A Survey of Homomorphic Encryption for Nonspecialists, Caroline Fontaine and Fabien Galand Volume 2007, Article ID 13801, 10 pages Secure Multiparty Computation between Distrusted Networks Terminals, S.-C. S. Cheung and Thinh Nguyen Volume 2007, Article ID 51368, 10 pages Protection and Retrieval of Encrypted Multimedia Content: When Cryptography Meets Signal Processing, Zekeriya Erkin, Alessandro Piva, Stefan Katzenbeisser, R. L. Lagendijk, Jamshid Shokrollahi, Gregory Neven, and Mauro Barni Volume 2007, Article ID 78943, 20 pages Oblivious Neural Network Computing via Homomorphic Encryption, C. Orlandi, A. Piva, and M. Barni Volume 2007, Article ID 37343, 11 pages Efficient Zero-Knowledge Watermark Detection with Improved Robustness to Sensitivity Attacks,JuanRamon´ Troncoso-Pastoriza and Fernando Perez-Gonz´ alez´ Volume 2007, Article ID 45731, 14 pages Anonymous Fingerprinting with Robust QIM Watermarking Techniques, J. P. Prins, Z. Erkin, andR.L.Lagendijk Volume 2007, Article ID 31340, 13 pages Transmission Error and Compression Robustness of 2D Chaotic Map Image Encryption Schemes, Michael Gschwandtner, Andreas Uhl, and Peter Wild Volume 2007, Article ID 48179, 16 pages Hindawi Publishing Corporation EURASIP Journal on Information Security Volume 2007, Article ID 82790, 1 page doi:10.1155/2007/82790 Editorial Signal Processing in the Encrypted Domain Alessandro Piva1 and Stefan Katzenbeisser2 1 Department of Electronics and Telecommunications, University of Florence, Via S. Marta 3, 50139 Firenze, Italy 2 Information & System Security Group, Philips Research Europe, High Tech Campus 34 MS 61, 5656 AE Eindhoven, The Netherlands Correspondence should be addressed to Alessandro Piva, [email protected]fi.it Received 31 December 2007; Accepted 31 December 2007 Copyright © 2007 A. Piva and S. Katzenbeisser. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Recent advances in digital signal processing enabled a num- The first part of the special issue contains three survey ber of new services in various application domains, ranging papers: Fontaine and Galand give an overview of homomor- from enhanced multimedia content production and distri- phic encryption, which is one of the key tools for signal pro- bution, to advanced healthcare systems for continuous health cessing in the encrypted domain, in their paper “A survey of monitoring. At the heart of these services lies the ability homomorphic encryption for nonspecialists.” An introduc- to securely manipulate “valuable” digital signals in order to tion to the field of secure multiparty computation is provided satisfy security requirements such as intellectual property by the paper “Secure multiparty computation between dis- management, authenticity, privacy, and access control. Cur- trusted networks terminals” by Cheung and Nguyen. Finally, rently available technological solutions for “secure manipu- research in the area of signal processing under encryption is lation of signals” apply cryptographic primitives by build- surveyed in the paper “Protection and retrieval of encrypted ing a secure layer on top of existing signal processing mod- multimedia content: when cryptography meets signal pro- ules, able to protect them from leakage of critical infor- cessing” by Erkin et al. mation, assuming that the involved parties or devices trust The second part of the special issue contains four re- each other. This implies that the cryptographic layer is used search papers. Orlandi et al. introduce the notion of obliv- only to protect the data against access through unautho- ious computing with neural networks in the paper “Obliv- rized third parties or to provide authenticity. However, this ious neural network computing via homomorphic encryp- is often not enough to ensure the security of the applica- tion.” Troncoso-Pastoriza and Perez-Gonz´ alez´ present new tion, since the owner of the data may not trust the process- protocols for zero-knowledge watermark detection in their ing devices, or those actors that are required to manipulate paper “Efficient zero-knowledge watermark detection with them. improved robustness to sensitivity attacks.” Prins et al. It is clear that the availability of signal processing algo- show in their paper “Anonymous fingerprinting with robust rithms that work directly on encrypted signals would be of QIM watermarking techniques” how advanced quantization- great help for application scenarios where signals must be index-modulation watermarking schemes can be used in produced, processed, or exchanged securely. conjunction with buyer-seller watermarking protocols. Fi- Whereas the development of tools capable of processing nally, Gschwandtner et al. explore properties of specialized encrypted signals may seem a formidable task, some recent, image encryption schemes in their paper “Transmission er- still scattered, studies, spanning from secure embedding and ror and compression robustness of 2D chaotic map image detection of digital watermarks and secure content distri- encryption schemes.” bution to compression of encrypted data and access to en- Finally, we would like to thank all the authors, as well as crypted databases, have shown that performing signal pro- all reviewers, for their contribution to this issue. We hope cessing operations in encrypted content is indeed possible. that the readers will enjoy this special issue and that it en- We are delighted to present the first issue of a journal, en- courages more colleagues to devote time to this novel and tirely devoted to signal processing in the encrypted domain. exciting field of research. The issue contains both survey papers allowing the reader to become acquainted with this exciting field, and research pa- Alessandro Piva pers discussing the latest developments. Stefan Katzenbeisser Hindawi Publishing Corporation EURASIP Journal on Information Security Volume 2007, Article ID 13801, 10 pages doi:10.1155/2007/13801 Review Article A Survey of Homomorphic Encryption for Nonspecialists Caroline Fontaine and Fabien Galand CNRS/IRISA-TEMICS, Campus de Beaulieu, 35042 Rennes Cedex, France Correspondence should be addressed to Caroline Fontaine, [email protected] Received 30 March 2007; Revised 10 July 2007; Accepted 24 October 2007 Recommended by Stefan Katzenbeisser Processing encrypted signals requires special properties of the underlying encryption scheme. A possible choice is the use of ho- momorphic encryption. In this paper, we propose a selection of the most important available solutions, discussing their properties and limitations. Copyright © 2007 C. Fontaine and F. Galand. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1. INTRODUCTION momorphic encryption; it is particularly aimed at noncryp- tographers, providing guidelines about the main characteris- The goal of encryption is to ensure confidentiality of data tics of encryption primitives: algorithms, performance, secu- in communication and storage processes. Recently, its use rity. Section 3 provides a survey of homomorphic encryption in constrained devices led to consider additional features, schemes published so far, and analyses their characteristics. such as the ability to delegate computations to untrusted Most schemes we describe are based on mathematical no- computers. For this purpose, we would like to give the un- tions the reader may not be familiar with. In the cases these trusted computer only an encrypted version of the data to notions can easily be introduced, we present them briefly. process. The computer will perform the computation on this Thereadermayreferto[15] for more information concern- encrypted data, hence without knowing anything on its real ing those we could not introduce properly, or algorithmic value. Finally, it will send back the result, and we will decrypt problems related to their computation. it. For coherence, the decrypted