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This chapter concludes this book on Watermarking Security and I hope that the reader will have a better view of the ins and outs of this domain. If watermarking security may look like a cat and mice game that is never ending, we can however state several important conclusions derived for the large variety of researches that have been conducted but there are also fascinating related problems that still need to be solved. The goal of this last chapter is to list the different outputs and open questions related to watermarking security but also general security of information forensics.

Digital watermarking has been introduced in the 1990s as a complementary technology for copyright protection. In an effort to anticipate hostile behavior of adversaries, the research community is constantly introducing new attacks to benchmark watermarking systems. In this paper, we present a generic attack strategy based on block replacement. As multimedia content is often highly repetitive, the attack exploits signal's self-similarities to replace each signal block with another, perceptually similar one. Guided by the principles of the proposed attack framework, we implemented three attack algorithms for different types of multimedia content: video shots, audio tracks and still images. Finally, considering the effectiveness of the proposed algorithms, we identify the properties that a watermark should have to counter this attacking strategy

To be relevant in copyright protection scenarios, watermarking systems need to provide appropriate levels of security. This paper investigates the security of a popular 3D watermarking method that alters the histogram of distances between the vertices of a surface mesh and its center of mass using a quadratic programming formulation.We study two conventional security mechanisms, namely (i) obfuscating the support of the content used for watermarking and (ii) relying on random projections to obfuscate the watermarking subspace. The different attacks surveyed throughout the paper clearly highlight the limitations of this family of 3D watermarking systems with respect to security.

Watermarking digital video material is usually considered as watermarking a sequence of still images. However, such a frame-by-frame approach is very risky since straightforward embedding strategies can result in poor performance in terms of security i.e., against hostile attacks. As examples, two very common video-watermarking systems will be presented as well as the associated intra-video collusion attacks which defeat them. Then, both watermark modulation and embedding strength modulation will be surveyed to design alternative embedding strategies which exhibit superior performance against such attacks. Nevertheless, it will also be shown that an expert attacker can still construct an effective watermark removal attack. Finally, there will be a discussion to assert whether or not security against intra-video collusion can be achieved with such blind frame-by-frame embedding strategies.

Digital watermarking was introduced at the end of the 20th century to provide means of enforcing copyright protection once the use and distribution of digital multimedia data have exploded. This technology has first been intensively investigated for still images and recent efforts have been put to exhibit unifying characteristics. On the other hand, the situation is rather different in the context of video watermarking, where unrelated articles are scattered throughout the literature. The purpose of this paper is consequently to give an in-depth overview of video watermarking and to point out that it is not only a simple extension of still images watermarking. New applications have to be considered, specific challenges have to be taken up and video-driven approaches have to be investigated.

Content owners are reluctant to deliver premium content to open devices due to the risk of piracy and the corresponding potential for loss of revenue. To lift this deadlock, there is increasing interest in incorporating watermarking-based tracing mechanisms onto mobile devices such as smart phones and tablets. The scarcity of resources calls for innovative watermarking paradigms. In this demo, we will exemplify how two-step bitstream video watermarking could be exploited to address this challenge and why it needs to be adapted to cope with the characteristics of HTTP adaptive streaming.

HTTP adaptive streaming has become the dominant solution for broadband streaming delivery. Essentially, the server delivers small chunks of content in response to queries from a player, that can alternate between different qualities of content depending on its rendering capabilities and the network condition. In this paper, we highlight that the frequent switches of this popular delivery mechanism are deemed to interfere with the payload modulation of bit-stream video watermarking systems. We then propose a generic strategy to cope with such transmission and showcase its efficiency in practice with a watermarking system that operates directly in the H.264/AVC CABAC bit-stream. Eventually, we evaluate the robustness of the proposed solution against standard attacks.

Content protection relies on several security mechanisms: (i) encryption to prevent access to the content during transport, (ii) trusted computation environment to prevent access during decoding, and we can also add (iii) forensic watermarking to deter content re-acquisition at rendering. With the advent of next generation video and the ever increasing popularity of embedded devices for content consumption, there is a need for new content protection solutions that rely less on hardware. In this context, we propose an architecture that combines the ARM TrustZone technology, an hypervised environment built on Genode and a bit stream watermarking algorithm that inserts serialization marks on the fly in an embedded device. As a result, an attacker cannot get access to video assets in clear form and not watermarked. Reported performances measurements indicate that the induced computational overhead is reasonable.

The weighted overlap add (WOLA) technique is routinely used in audio processing to avoid introducing audible clicks. This process introduces inter-dependencies between WOLA coefficients and it is thus necessary to revisit watermarking algorithms to accommodate for such dependencies and prevent introducing self-inflicted interferences. In this paper, we focus on an existing phase quantization based audio watermarking system. Instead of the original computationally expensive ad-hoc process for dealing with the inter-dependencies between WOLA coefficients, we introduce an alternative strategy. Experimental results show a notable reduction of the complexity while maintaining robustness performances.

In this industrial exhibit, Technicolor will showcase various technologies developed to protect digital audio-visual material all along the media value chain, from production to distribution, including forensics services in case pirated content is detected. The exhibit will be organized around Technicolor's proprietary technologies in video fingerprinting and audio/video watermarking.

We compare the performance of three steganalysis system for detection of plusmn1 steganography. We examine the relative performance of each system on three commonly used image databases. Experimental results clearly demonstrate that both absolute and relative performance of all three algorithms vary considerably across databases. This sensitivity suggests that considerably more work is needed to develop databases that are more representative of diverse imagery. In addition, we investigate how performance varies based on a variety of training and testing assumptions, specifically (i) that training and testing are performed for a fixed and known embedding rate, (ii) training is performed at one embedding rate, but testing is over a range of embedding rates, (iii) training and testing are performed over a range of embedding rates. As expected, experimental results show that performance under (ii) and (iii) is inferior to (i). The experimental results also suggest that test results for different embedding rates should not be consolidated into a single score, but rather reported separately. Otherwise, good performance at high embedding rates may mask poor performance at low embedding rates.

International audience; Benchmarking watermarking systems now goes beyond only evaluating the ability of the embedded watermark to with- stand common signal primitives such as filtering, resampling, lossy compression, D/A-A/D conversions, etc. Evaluation procedures have to consider how much information leaks from a watermarking system since such knowledge could prove most helpful to design very powerful attacks. This paper further refines an attack on dirty paper watermarking schemes which relies on security weaknesses i.e. information leakage. In particular, additional constraints are introduced to be able to handle ‘complex' trellises. Moreover, the ef- ficiency of this attack has been evaluated for different trel- lis configurations. Quite counter-intuitively, increasing the number of states in the trellis seems to enhance both the robustness and the security of the system.

International audience; This paper analyses the security of dirty paper trellis (DPT) watermarking schemes which use both informed coding and informed em- bedding. After recalling the principles of message embedding with DPT watermarking, the secret parameters of the scheme are highlighted. The security weaknesses of DPT watermarking are then presented: in the wa- termarked contents only attack (WOA) setup, the watermarked data-set exhibits clusters corresponding to the different patterns attached to the arcs of the trellis. The K-means clustering algorithm is used to estimate these patterns and a co-occurrence analysis is performed to retrieve the connectivity of the trellis. Experimental results demonstrate that it is possible to accurately estimate the trellis configuration, which enables to perform attacks much more efficient than simple additive white Gaus- sian noise (AWGN).

Digital watermarking has first been introduced as a possible way to ensure intellectual property (IP) protection. However, fifteen years after its infancy, it is still considered as a young technology and digital watermarking is far from being introduced in Digital Right Management (DRM) frameworks. A possible explanation is that the research community has so far mainly focused on the robustness of the embedded watermark and has almost ignored security aspects. For IP protection applications such as fingerprinting and copyright protection, the watermark should provide means to ensure some kind of trust in a non secure environment. To this end, security against attacks from malicious users has to be considered. This paper will focus on collusion attacks to evaluate security in the context of video watermarking. In particular, security pitfalls will be exhibited when frame-by frame embedding strategies are enforced for video watermarking. Two alternative strategies will be surveyed: either eavesdropping the watermarking channel to identify some redundant hidden structure, or jamming the watermarking channel to wash out the embedded watermark signal. Finally, the need for a new brand of watermarking schemes will be highlighted if the watermark is to be released in a hostile environment, which is typically the case for IP protection applications.

Security issues have almost been ignored during the first decade of digital watermarking. As a result, many released watermarking algorithms are weak against hostile intelligence. For instance, block replacement attacks defeat watermarking systems which do not consider the self-similarities of the host signal during embedding. Such attacks replace each signal block with another one, or a combination of other ones, taken at a different location. In this paper, a novel strategy will be presented to generate a signal coherent watermark to achieve immunity against block replacement attacks. The basic idea consists in imposing a linear relationship between watermark samples embedded at different locations, with respect to their local neighborhoods which are characterized with Gabor features.

Multimedia digital data is highly redundant: successive video frames are very similar in a movie clip, most songs contain some repetitive patterns, etc. This property can consequently be exploited to successively replace each part of the signal with a similar one taken from another location in the same signal or with a combination of similar parts. Such an approach is all the more pertinent when video content is considered since such signals exhibit both temporal and spatial self-similarities. To counter such attacking strategies, it is necessary to ensure that embedded watermarks are coherent with the redundancy of the host content. To this end, both motion-compensated watermarking and self-similarities inheritance will be surveyed.

Recent efforts for watermarking digital video extend the results obtained for still image watermarking. As a result, most of the proposed algorithms rely on a frame-by-frame approach. Such an adaptation leads to unreliable algorithms in terms of security. The goal of this article is to stress the problem of collusion when digital watermarked data is distributed at large scale and especially intra-video collusion in the context of video. Three simple collusion attacks are described before being evaluated on two alternative video watermarking algorithms based on the spread spectrum technique. Finally, some experimental results are presented confirming the danger of intra-video collusion and some perspectives are discussed.

This paper reviews recent research on information-theoretic aspects of information hiding. Emphasis is placed on applications requiring high payload (e.g., covert communications). Information hiding may be viewed as a game between two teams (embedder/decoder vs. attacker), and optimal information-embedding and attack strategies may be developed in this context. This paper focuses on several such strategies, including a framework for developing near-optimal codes and universal decoders. The suboptimality of spread-spectrum strategies follows from the analysis. The theory is applied to image watermarking examples.

The security issue has been neglected for a long time in digital watermarking. Recent results for video watermarking have pointed out that existing watermarking schemes are not secure, i.e., a hostile intelligence succeeds in removing the hidden watermarks. In particular, for a given secret key, many watermarking schemes embed watermarks which lie in the same low-dimensional subspace whatever the host data is. We show that this subspace can be quite easily estimated with an efficient principal component analysis (PCA). For storage convenience, an online expectation-maximization (EM) algorithm is considered. Once this watermarking subspace has been estimated, an attacker only has to project incoming data onto the orthogonal of this subspace to remove the watermark.

During the last decade, a significant effort has been put into designing watermarking algorithms. The watermarking community now needs some advanced attacks and fair benchmarks in order to compare the performances of different watermarking technologies. Moreover, attacks permit the weaknesses of an algorithm to be found and consequently trigger further research in order to overcome the problem. These ideas motivated the creation of the European Certimark project. After a short definition of dewatermarking, we present an original attack based on self similarities. This attack is then put to the test with three different publicly available watermarking tools. Finally, we discuss briefly the feasibility of a generic attack i.e. a dewatermarking attack which should succeed in removing whatever watermarks have been inserted by whatever watermarking tools.

Unauthorized digital copying is a major concern for multi-media content providers. Since copyright owners lose control over content distribution as soon as data is decrypted or unscrambled, digital watermarking has been introduced as a complementary protection technology. In an effort to anticipate hostile behaviors of adversaries, the research community is constantly introducing novel attacks to benchmark watermarking systems. In this paper, a generic block replacement attack will be presented. The underlying assumption is that multimedia content is highly repetitive. It should consequently be possible to exploit the self-similarities of the signal to replace each signal block with another perceptually similar one. Alternative methods to compute such a valid placement block will be surveyed in this paper. Then,experimental results on still images will be presented to the efficiency of the presented attack in comparison with other reference image processing operations. Finally, a will be conducted to exhibit the properties that a watermark should have to resist to this attack.