Digital watermarking is a key ingredient to copyright protection. It provides a solution to illegal copying of digital material and has many other useful applications such as broadcast monitoring and the recording of electronic transactions. Now, for the first time, there is a book that focuses exclusively on this exciting technology. Digital Watermarking covers the crucial research findings in the field: it explains the principles underlying digital watermarking technologies, describes the requirements that have given rise to them, and discusses the diverse ends to which these technologies are being applied. As a result, additional groundwork is laid for future developments in this field, helping the reader understand and anticipate new approaches and applications.

Digital Watermarking

Usually, a proof of a theorem contains more knowledge than the mere fact that the theorem is true. For instance, to prove that a graph is Hamiltonian it suffices to exhibit a Hamiltonian tour in it; however, this seems to contain more knowledge than the single bit Hamiltonian/non-Hamiltonian.In this paper a computational complexity theory of the “knowledge” contained in a proof is developed. Zero-knowledge proofs are defined as those proofs that convey no additional knowledge other than the correctness of the proposition in question. Examples of zero-knowledge proof systems are given for the languages of quadratic residuosity and 'quadratic nonresiduosity. These are the first examples of zero-knowledge proofs for languages not known to be efficiently recognizable.

/pdf/the-knowledge-complexity-of-interactive-proof-systems-31apre0ecf.pdf

The knowledge complexity of interactive proof-systems

Media objects are transformed into active, connected objects via identifiers embedded into them or their containers. In the context of a user's playback experience, a decoding process extracts the identifier from a media object and possibly additional context information and forwards it to a server. The server, in turn, maps the identifier to an action, such as returning metadata, re-directing the request to one or more other servers, requesting information from another server to identify the media object, etc. The linking process applies to broadcast objects as well as objects transmitted over networks in streaming and compressed file formats.

Connected audio and other media objects

Processing encrypted signals requires special properties of the underlying encryption scheme. A possible choice is the use of homomorphic encryption. In this paper, we propose a selection of the most important available solutions, discussing their properties and limitations.

/pdf/a-survey-of-homomorphic-encryption-for-nonspecialists-3h2jygsf38.pdf

A Survey of Homomorphic Encryption for Nonspecialists

The presently claimed invention generally relates to deriving and/or utilizing content signatures (e.g., so-called “fingerprints”). One claim recites a method of generating a fingerprint associated with a content item including: pseudo-randomly selecting a segment of the content item; and utilizing a processor or electronic processing circuitry, fingerprinting the selected segment of content item as at least an identifier of the content item. Of course, other claims and combination are provided as well.

Methods, Apparatus and Programs for Generating and Utilizing Content Signatures

The goal of zero-knowledge watermark detection is to allow a prover to soundly convince a verifier of the presence of a watermark in certain stego-data without revealing any information which the verifier can use to remove the watermark. Existing proposals do not achieve this goal in terms of definition (not formally zero-knowledge), security (unproven) and coverage (handle only blind watermark detection).In this paper we define zero-knowledge watermark detection precisely. We then propose efficient and provably secure zero-knowledge protocols for blind and non-blind versions of a well-known class of watermarking schemes. Using these protocols the security and efficiency of many watermark based applications can be significantly improved.As an example of use we propose concrete protocols for direct proof of ownership which enable offline ownership proofs, i.e., copyright holders can prove their rightful ownership to anyone without involving a trusted third party in the actual proof protocol.

/pdf/zero-knowledge-watermark-detection-and-proof-of-ownership-212kmkop7r.pdf

Zero-Knowledge Watermark Detection and Proof of Ownership

Protection of digital property has become crucial in the widespread and rapidly growing use of digital media. Making the misuse of copyrighted works detectable, and thus deterring people from misuse, is the most promising measure currently known. To achieve this, most proposals apply watermarking techniques and focus on resolving the ownership in disputes which may arise after a misuse has been detected. Here a trusted third party (judge) compares the ownership claims of disputing parties. However, this does not necessarily imply determining the rightful owner, since she might not be participating in the dispute. Moreover, in contrast to disputes, one is in practice often confronted with only a single claim of ownership, e.g., in electronic market places where buyers intend to purchase digital items from someone claiming to be the rightful copyright holder. Proof of ownership is highly desirable in such situations because on the one hand, the buyers are ensured not to buy digital items from fake copyright holders and on the other hand, the copyright holders are protected against unauthorized reselling of their digital works.

Proving Ownership of Digital Content

Protocol attacks against watermarking schemes pose a threat to modern digital rights management systems; for example, a successful attack may allow to copy a watermark between two digital objects or to forge a valid watermark. Such attacks enable a traitor to hinder a dispute resolving process or accuse an innocent party of a copyright infringement. Secure DRM systems based on watermarks must therefore prevent such protocol attacks. In this paper we introduce a formal framework that enables us to assert rigorously the security of watermarks against protocol attacks. Furthermore, we show how watermarking schemes can be secured against some protocol attacks by using a cryptographic signature of a trusted third party.

Watermarking schemes provably secure against copy and ambiguity attacks

Today the standard means for secure transactions in the World Wide Web (WWW) are the SSL/TLS protocols, which provide secure (i.e., private and authentic) channels between browsers and servers. As protocols SSL/TLS are considered secure. However, SSL/TLS's protection ends at the “transport/session layer” and it is up to the application (here web browsers) to preserve the security offered by SSL/TLS.

In this paper we provide evidence that most web browsers have severe weaknesses in the browser-to-user communication (graphical user interface), which attackers can exploit to fool users about the presence of a secure SSL/TLS connection and make them disclose secrets to attackers. These attacks, known as “Visual Spoofing”, imitate certain parts of the browser's user interface, pretending that users communicate securely with the desired service, while actually communicating with the attacker. Therefore, most SSL/TLS protected web applications can not be considered secure, due to deficiencies in browser's user interfaces.

Furthermore, we characterise Visual Spoofing attacks and discuss why they still affect today's WWW browsers. Finally, we introduce practical remedies, which effectively prevent these attacks and which can easily be included in current browsers or (personal) firewalls to preserve SSL/TLS's security in web applications.

/pdf/visual-spoofing-of-ssl-protected-web-sites-and-effective-51jfny60sq.pdf

Visual spoofing of SSL protected web sites and effective countermeasures

A system for proving ownership of digital media works. Proof of ownership of such type of work is provided by a protocol for registering a work with a registration center thus providing the rightful owner or copyright holder of the work with an ownership certificate. There is also provided a protocol for proving to another party who is a prospective buyer or licensee, that an ownership claim is correct and valid by providing the ownership certificate when required. Another protocol is utilized for showing to a third party, a prospective buyer or licensee, that a second party has correctly obtained the corresponding work from the rightful copyright owner.

André Adelsbach

Papers

Zero-Knowledge Watermark Detection and Proof of Ownership

Proving Ownership of Digital Content

Watermarking schemes provably secure against copy and ambiguity attacks

Visual spoofing of SSL protected web sites and effective countermeasures

Method and system for proving ownership of digital data