Watermarking protocols are used in conjunction with digital watermarking techniques to protect digital copyright on the Internet. They define the schemes of the web transactions by which buyers can purchase protected digital content distributed by content providers in a secure manner. Over the last few years, significant examples of watermarking protocols have been proposed in literature. However, a detailed examination of such protocols has revealed a number of problems that have to be addressed in order to make them suited for current web context. Therefore, based on the most relevant problems derived from literature, this article identifies the main challenges posed by the development of watermarking protocols for web context and presents a watermarking protocol that follows a new secure, buyer-centric and mediated design approach able to meet such challenges.

Digital watermarking is recognized as an innovative technique developed to deal with the problem of copyright protection of digital content distributed on the Internet. Such a technique can address the problem of asserting authorship but cannot directly solve the problem of determining accountability when piracy occurs. Therefore, it is necessary to implement watermarking protocols to determine whether a user illegally possesses content distributed by content providers as well as to protect the entire digital asset of the web-based distribution and of the associated rights. In this paper, the author reviews and discusses merits and limitations of relevant proposals existing in the literature in thefield of watermarking protocols, identifies open issues and challenges, and presents a novel watermarking protocolablebothtosolvespecificdocumentedproblemsandtomeettherequirementsofrobustness, security, modularity and flexibility needed in the current models of web-based content distribution.

The advances in networking and multimedia technologies have created opportunities for producers of digital content. However, the ability for anyone to make perfect copies of digital content and the ease by which copies can be distributed facilitate misuse, illegal distribution, plagiarism, misappropriation. Moreover, popular peer-to-peer software are widely used by Internet "pirates" to illegally share digital copyrighted content, thus violating the legal rights of the copyright owners. Known solutions like Digital Rights Management (DRM) systems aim at protecting and enforcing the legal rights associated with the use of digital content distributed on the Internet, but they may also disturb the balance between the information creation and distribution, and give rise to problems concerning with privacy. In fact, "fair use" and privacy are often invoked by web users: the former in order to prevent copyright owners from having the exclusive control over their creations than the copyright law intends, and the latter in order to preserve the ownership and distribution of confidential data. This paper reports on the most important problems tied to the use of DRM systems and, in the light of the current forensic trends, provides a number of suggestions that can be helpful to meet the conflicting interests of web users and content providers.

The digital rights management (DRM) systems aim at protecting and enforcing the legal rights associated with the use of digital content distributed on the Internet. Most of such systems use watermarking techniques to implement the content protection. Although the effectiveness of the implemented protection strictly depends on the adopted watermarking techniques, an important role is also played by watermarking protocols. They define the scheme of the interactions that have to take place among the entities involved in the processes of content protection and Web-based distribution governed by the DRM systems. This paper presents a DRM system developed as a Web software platform to implement the copyright protection of multimedia digital content distributed on the Internet. The DRM system is based on a watermarking protocol previously developed by the authors, and has been designed as a service oriented architecture composed of a federation of coordinated Web entities that play distinct roles and interact within a trusted environment.

Hybrid sensor networks (HSNs), made up of many static sensors interacting with a limited number of mobile robotic sensors, can support a variety of applications in which assisted navigation, implemented for mobile robotic sensors, performs requested operations in hostile environments, where the human presence is impracticable. On the other hand, the limited on-board battery energy of the sensor nodes imposes hard constraints to the wireless communication and computing capabilities of such nodes, thus limiting the capacity of a HSN to run an application for a period of interest without human intervention. These considerations have motivated this paper, which describes a method to estimate the energy consumption under changeable working conditions in a HSN running an assisted navigation algorithm based on the "credit field" concept.

In hybrid sensor networks (HSNs) one or more mobile sensor nodes can interact with other mobile sensor nodes or static ones in order to collaboratively perform specific tasks. Such networks can support applications in which assisted navigation is implemented for mobile sensor nodes that carry out requested operations through a monitored environment. To this end, several assisted navigation algorithms have been proposed within the HSNs scope with the goal of overcoming the typical problems of classic sensor networks (SNs), such as limited transmission power and lean autonomy in terms of computing and memory capacity. Nevertheless, the distributed and highly dynamic nature of such algorithms still makes their implementation in a real scenario a difficult task. In this paper we present an improved version of the assisted navigation algorithm based on the "credit field" concept. The algorithm has been designed for HSNs and implemented in Agilla, a middleware running on top of TinyOS and supporting a programming paradigm based on mobile agents. The implementation has been tested on a HSN that employs Mica2 Motes as static sensor nodes and the Lego Mindstorms robot integrated with a Stargate node developed by Crossbow as a mobile sensor node.

Digital watermarking is considered to be a main technology for the copyright protection of multimedia digital content distributed on the Internet. However, watermarking procedures can effectively support copyright protection processes only if they are applied by employing specific watermarking protocols, which define the scheme of the interactions that have to take place among the entities involved in the content protection and web-based distribution. To this end, a number of current watermarking protocols can attain important achievements, such as the correct authentication of buyers without exposing their identities during web transactions and the capability of resorting to trusted watermark certification authorities to ensure a copyright protection process that is able to correctly take into account the rights of both buyers and sellers. However, these protocols are often not suitable for web context, where buyers are usually neither provided with digital certificates issued by trusted certification authorities nor able to autonomously perform complex security actions to purchase digital content distributed by web-based content providers. This paper presents an improved version of a web-oriented and interactive anonymous buyer-seller watermarking protocol previously presented by the author. The protocol overcomes the drawbacks affecting relevant protocols existing in literature, and is based on a design approach that makes it suitable for web contexts.