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Selective encryption of visual data and especially MPEG has attracted a considerable number of researchers in recent years. Scalable visual formats are offering additional functionality, which is of great benefit for streaming and networking applications. The MPEG-2 and MPEG-4 standards provide a scalability profile in which a resolution scalable mode is specified. In this paper we evaluate a selective encryption approach on the basis of our hierarchical MPEG video codec. [ABSTRACT FROM AUTHOR]

Chaotic mixing based encryption schemes for visual data are shown to be robust to lossy compression as long as the security requirements are not too high. This property facilitates the application of these ciphers in scenarios where lossy compression is applied to encrypted material - which is impossible in case traditional ciphers should be employed. If high security is required chaotic mixing loses its robustness to compression, still the lower computational demand may be an argument in favor of chaotic mixing as compared to traditional ciphers when visual data is to be encrypted. [ABSTRACT FROM AUTHOR]

Implementing X.509 based public-key infrastructure requires following a complex set of rules to establish if a public key certificate is valid. The XML Key Management Specification has been developed as one way in which the implementation burden can be reduced by moving some of this complexity from clients and onto a server. In this paper we give a brief overview of the XML key management specification standard, and describe how, in addition to the above, this system also provides us with the means to sensibly break many of the rules specified for X.509 based public key infrastructure. [ABSTRACT FROM AUTHOR]

The goal of service oriented architectures (SOA) is to allow a message based and loosely coupled interaction between different web services. This approach allows the orchestration of web services in distributed, heterogeneous applications where the different services can be implemented in different programming languages, run on different machines and be based on different protocols. The adoption of web services to integrate systems within an organization and with partners is strongly dependent on the security standards that accompany service oriented architectures (SOA). The XML (Extensible Markup Language) Signature standard plays a key role here. For protecting such a distributed application, XML Signatures are used on several levels and for different challenges, for example to guarantee the integrity and authenticity of the exchanged messages and their authentication information, as well as the audit trails and to provide non-repudiation. The paper describes the role of XML Signatures for protecting Enterprise Service Bus (ESB) based SOA applications. [ABSTRACT FROM AUTHOR]

Nowadays, the setup of seamless, cross-organizational working environments is a challenging task, mainly because of security-related problems. The available options for cross-domain collaboration are often dysfunctional, expensive and not in line with the organization's business needs. Despite the proliferation of claims-based mechanisms like SAML, WS-Trust or WS-Federation, additional guidance is necessary how to effectively apply these technologies. The architectural pattern and ideas presented in this talk are an attempt to solve a common class of problems in collaboration space. [ABSTRACT FROM AUTHOR]

The XML-Security Plug-In is a freely available plug-in for the Eclipse platform and provides versatile XML security features in an educational software like environment. Users can experiment with XML security and inform themselves about the corresponding W3C recommendations. The aim of the plug-in is to raise interest in XML security functions and especially encourage users to sign and encrypt their personal data and messages. This is a common aim with CrypTool, an educational software for modern cryptography. This article will explain the basic features of the XML-Security Plug-In and give a perspective on the cooperation with the more general CrypTool. [ABSTRACT FROM AUTHOR]

The digital signature is one of the most important cryptographic primitives. It provides data integrity, message authentication and non-repudiation, which are required attributes in security critical services, such as electronic commerce, voting or health care. Whereas previous data formats for digital signatures concentrated on signing the entire document, the XML signature standard is feasible to secure complex workflows on a document with multiple signatures. In a proof of concept implementation we demonstrate that verifying and trustworthily displaying of signed documents is realizable in standard Web browsers. The focus of our work are multisigned XML documents that introduce new requirements particularly in the field of presentation. Keywords: Visualisation, WYSIWYS, XML, XML Signature, XPath, XSL Transformation, Web Browser. [ABSTRACT FROM AUTHOR]

The technique of electronic time-stamping allows a client to get an electronic proof of the existence of a document at a speci.c point in time. A simple way to achieve this is to produce a digital signature over the pair (document,time). Linked time-stamps have an advantage over these simple time-stamps because they construct a veri.able link between time-stamps. In this paper, we discuss how to include linked time-stamps in the OASIS Digital Signature Services standard. We highlight the problem points when introducing a sub-pro.le of this standard, and we describe some additional structures that are needed to accommodate a broad range of linked time-stamping schemes. Keywords: Linked time-stamping, Digital Signature Services, XML security. [ABSTRACT FROM AUTHOR]

E-mail is one of the oldest applications on the internet. Clients have to adhere to message formats that have been defined in RFC 822 [13] back in 1982, and at the same time be able to transport all types of content. Additionally, there are severe restrictions for the use of both encryption and digital signatures due to the adherence to RFC822. In this paper we propose a new approach based on our XMaiL project: Using the XMaiL parser, we transform header and body of the mail into an XML object. This transformation preserves both the MIME and the PKCS#7 structure of the mail. We describe the security enhancements that are possible using XMaiL such as selective encryption and signature of parts of the e-mail, or signature of critical fields in the header of the mail. [ABSTRACT FROM AUTHOR]

In next generation wireless networks, an application must be capable of rating service information in real-time and prior to initiation of the service it is necessary to check whether the end user's account provides coverage for the requested service. However, to provide prepaid services effectively, credit-control should have minimal latency. In an endeavor to support real-time credit-control for Mobile IPv6 (MIPv6), we design an architecture model of credit-control authorization. The proposed integrated model combines a typical credit-control authorization procedure into the MIPv6 authentication procedure. We implement it on a single server for minimal latency. Thus, the server can perform credit-control authorization and MIPv6 authentication simultaneously. Implementation details are described as software blocks and units. In order to verify the feasibility of the proposed model, latency of credit-control authorization is measured according to various Extensible Authentication Protocol (EAP) authentication mechanisms. The performance results indicate that the proposed approach has considerably low latency compared with the existing separated models, in which credit-control authorization is separated from the MIPv6 authentication. Keywords: Mobile node, prepaid, authorization, Mobile IPv6. [ABSTRACT FROM AUTHOR]

The Palm OS operating system for Personal Digital Assistants (PDAs) and mobile phones has a weak security architecture, which introduces all sorts of security problems. This paper specifically targets the problem of malicious code. The main contribution of this work is the in-depth analysis of different vulnerabilities in Palm OS and the ways in which they can be exploited by malicious code. Furthermore, the key reasons for this problem are discussed and some suggestions for improvement are formulated. Keywords: malicious code, worms, mobile operating systems, Palm OS. [ABSTRACT FROM AUTHOR]

Wireless communication demands for specialized protocols secure against attacks on the radio path while fitting the limited calculation and memory capabilities of mobile terminals. To ensure accessibility of mobile services beyond a user's home network, signing on a foreign network should be possible. The latter must be able to authenticate a user without learning any secret registration data. Chouinard et al.[DBC01] introduce the Secure Authentication Protocol for this purpose. In this paper, an exhaustive security analysis of the protocol is presented. First, it is mapped to a coloured petri net. Then, two different intruder models are developed and integrated separately into it. The state spaces of the two nets are calculated; they each contain a set of nodes representing all reachable states. Both are examined to detect states where any security objective is violated indicating a security flaw in the protocol. As there are no such states in both nets, the protocol is proven secure. Keywords: Secure Authentication Protocol, Coloured Petri Nets, Formal Protocol Verification, State Space Analysis, Security Analysis. [ABSTRACT FROM AUTHOR]

In the 4G mobile networks which are expected to be very complex systems interconnecting various technologies, new intelligent services will need to be aware of various contexts. In this paper, we present the context management framework that exploits the agent technology in mobile communications and services. We focus mainly on the seamless secure handover which uses context information regarding location privacy, security, network environment, and QoS priority. We designed QoS Broker that can perform the autonomous decision making for context-aware handover without the direct intervention of users. To minimize the signaling overhead, we present an efficient context transfer mechanism among the Brokers. We also designed the context model for the seamless vertical handovers so that the Brokers could ensure the right context is available in the right place at right time. We developed the testbed and analyzed the performance of QoS-aware secure roaming with context transfer. Analytical results show that our context-aware vertical handover provides better performance and security with lower latency. Keywords: 4G, context-aware, home network, QoS, vertical handover, mobile networks, security. [ABSTRACT FROM AUTHOR]

This paper presents our progression in the search for reliable anomaly-based intrusion detection mechanisms. We investigated different options of stochastic techniques. We started our investigations with Markov chains to detect abnormal traffic. The main aspect in our prior work was the optimization of transition matrices to obtain better detection accuracy. First, we tried to automatically train the transition matrix with normal traffic. Then, this transition matrix was used to calculate the probabilities of a dedicated Markov sequence. This transition matrix was used to find differences between the trained normal traffic and characteristic parts of a polymorphic shellcode. To improve the efficiency of this automatically trained transition matrix, we modified some entries in a way that byte-sequences of typical shellcodes substantially differs from normal network behavior. But this approach did not meet our requirements concerning generalization. Therefore we searched for automatic methods to improve the matrix. Genetic algorithms are adequate tools if just little knowledge about the search space is available and the complexity of the problem is very hard (NP-complete). Keywords: intrusion detection, polymorphic shellcode detection, markov models, genetic algorithms, optimization. [ABSTRACT FROM AUTHOR]

In this paper, a refined sequential aggregate signature scheme from RSA that works for any modulus is presented, then a compact stimulation mechanism without a central, trusted authority for routing discovery in civilian ad hoc networks is proposed as an immediate application of this cryptographic primitive. Our protocol forces selfish nodes to cooperate and report actions honestly, thus enables our routing discovery protocol to resist selfish actions within our model. Keywords: Network security, Routing discovery protocol, Sequential aggregate signature. [ABSTRACT FROM AUTHOR]

In this paper a novel fusion approach for combining voice and online signature verification will be introduced. While the matching algorithm for the speaker identification modality is based on a single Gaussian Mixture Model (GMM) algorithm, the signature verification strategy is based on four different distance measurement functions, combined by multialgorithmic fusion. Together with a feature extraction method presented in our earlier work, the Biometric Hash algorithm, they result in four verification experts for the handwriting subsystem. The fusion results of our new subsystem on the multimodal level are elaborated by enhancements to a system, which was previously introduced by us for biometric authentication in HCI scenarios. Tests have been performed on identical data sets for the original and the enhanced system and the first results presented in this paper show that an increase of recognition accuracy can be achieved by our new multialgorithmic approach for the handwriting modality. Keywords: biometrics, combination, distance, fusion, handwriting, identification, matching score level, multialgorithmic, multimodal, voice. [ABSTRACT FROM AUTHOR]

The current WiFi access control framework descends from solutions conceived in the past for dial-up scenarios. A key difference between the two worlds is mobility: dial-up handles nomadic users, while modern wireless networks support continuous mobility through always-on personal devices. Not surprisingly, WiFi authentication does not exploit mobility in any way; on the contrary, mobility is perceived as a problem to be fixed by some fast-handoff solution. Though fast-handoff is indeed an open issue, mobility may even help to build security systems. The paper describes a decentralised access control framework for WiFi networks that exploits mobility to avoid a central authority to be always online. [ABSTRACT FROM AUTHOR]

In this paper, a new concept for classifying handwriting data and its analysis for biometric user authentication is presented. The concept's characteristic is the combination of syntax and semantics. It implies a determination of four distinct levels of syntax and semantics to lower complexity and structure information. We demonstrate the concept's impacts on on-line handwritings and the user verification, and clarify the benefit of applying information of higher levels of semantics within the authentication methods. As a result we are able to evaluate techniques for biometric user authentication. Furthermore, we precisely outline and reason a more accurate biometric user authentication system, due to the classification given by the Verifier-Tuple concept. Keywords: Biometrics, Security of Multimedia Content, Identification and Authentication. [ABSTRACT FROM AUTHOR]

With Federated Identity Management (FIM) protocols, service providers can request user attributes, such as the billing address, from the user's identity provider. Access to this information is managed using so-called Attribute Release Policies (ARPs). In this paper, we first analyze various shortcomings of existing ARP implementations; then, we demonstrate that the eXtensible Access Control Markup Language (XACML) is very suitable for the task. We present an architecture for the integration of XACML ARPs into SAML-based identity providers and specify the policy evaluation workflows. We also introduce our implementation and its integration into the Shibboleth architecture. [ABSTRACT FROM AUTHOR]

Electronic health records enable the global availability of medical data. This has numerous benefits for the quality of offered services. However, privacy concerns may arise as now both the patient's medical history as well as the doctor's activities can be tracked. In this paper, we propose an electronic health record system which allows the patient to control who has access to her health records. Furthermore, provided she does not misuse the system, a doctor will remain anonymous with respect to any central authority. [ABSTRACT FROM AUTHOR]

The topmost concern of users who are kept under surveillance by a CCTV-System is the loss of their privacy. To gain a high acceptance by the monitored users, we have to assure, that the recorded video-material is only available to a subset of authorized users under exactly previously defined circumstances. In this paper we propose a CCTV video surveillance system providing privacy in a distributed way using threshold multi-party computation. Due to the flexibility of the access structure, we can handle the problem of loosing private-key-shares that are necessary for reconstructing video-material as well as adding new users to the system. If a pre-defined threshold is reached, a shared update of the master secret and the according re-encryption of previously stored ciphertext without revealing the plaintext is provided. [ABSTRACT FROM AUTHOR]

Cryptographic techniques have been deployed to securely prove the presence of a watermark in stego-data without disclosing any security critical information to the detecting party. This paper presents a detailed practical construction and implementation results of a correlation-based non-blind watermarking scheme in the non-interactive zero-knowledge setting. We extensively describe the modifications and hurdles that had to be overcome to transform a well-known watermarking scheme - whose general detection principle is applied in many other known schemes - into a two-party setting where the critical detection input, i.e. the watermark vector and the original data is cryptographically concealed from the verifying party using a commitment scheme. Our prototype implementation is very efficient and is an evidence of the practical feasibility of zero-knowledge watermark detection. Keywords: Watermark, detection, implementation, zero-knowledge. [ABSTRACT FROM AUTHOR]

We suggest a graph-theoretic approach to steganography based on the idea of exchanging rather than overwriting pixels. We construct a graph from the cover data and the secret message. Pixels that need to be modified are represented as vertices and possible partners of an exchange are connected by edges. An embedding is constructed by solving the combinatorial problem of calculating a maximum cardinality matching. The secret message is then embedded by exchanging those samples given by the matched edges. This embedding preserves first-order statistics. Additionally, the visual changes can be minimized by introducing edge weights. We have implemented an algorithm based on this approach with support for several types of image and audio files and we have conducted computational studies to evaluate the performance of the algorithm. Keywords: Steganography, graph theory, information hiding. [ABSTRACT FROM AUTHOR]

In this paper, we analyze a possibility of reversibility of data-hiding techniques based on random binning from multimedia perspectives. We demonstrate the capabilities of unauthorized users to perform hidden data removal using solely a signal processing approach based on optimal estimation as well as consider reversibility on the side of authorized users who have the knowledge of key used for the message hiding. [ABSTRACT FROM AUTHOR]

Selective encryption techniques of JBIG encoded visual data are discussed. We are able to show attack resistance against common image processing attacks and replacement attacks even in case of restricting the amount of encryption to 1% - 2% of the data. The low encryption effort required is due to the exploitation of the interdependencies among resolution layers in the JBIG hierarchical progressive coding mode. [ABSTRACT FROM AUTHOR]

Networked multimedia applications have matured in recent years to be deployed in a larger scale in the Internet. Confidentiality is one of the primary concerns of these services for their commercial usages, e.g. in video on de mand services or in video conferences. In particular, video encryption algorithms are strongly required that fulfill real-time requirements. In this paper we present the video encryption algorithm Puzzle to encrypting video streams in software. It is fast enough to fulfill real-time constraints and to provide a sufficient security. Puzzle is a video compression independent algorithm which can be easily incorporated into existing multimedia systems. [ABSTRACT FROM AUTHOR]

The problem of controlling access to multimedia multicasts requires the distribution and maintenance of keying information. This paper proposes a new key embedded video codec for the media-dependent approach that involves the use of a data-dependent channel, and can be achieved for multimedia by using data embedding techniques. Using data embedding to convey keying information can provide an additional security and reduce the demand of bandwidth. In this paper, we develop a new statistical data embedding algorithm on compression-domain, then, by combining FEC (Forward Error Correction) algorithm and our proposed key information frame format. After a series of simulation experiments, we find that the new codec can satisfy the special demand of media-dependent approach. At the same time, the codec provides good performance. [ABSTRACT FROM AUTHOR]

Amortization schemes for authenticating streamed data have been introduced as a solution to reduce the high overhead that sign-each schemes suffer from. The hash chains structure of amortization schemes and the number of hash values appended to other packets affect the efficiency of the authentication scheme specially against packet loss. Which packets should have hashes appended to the signature packet and how many hashes to append to it have no solutions yet. This paper introduces a new hash chain construction to achieve longer resistance against packet loss and reduces the overhead. The proposed scheme consists of multiple connected chains, each chain links several packets together. Our scheme specifies clearly how to choose the packets that should have hashes appended to a signature packet, in addition to deriving their loss probability. We study the effect of the number of hashes that are appended to a signature packet on the overhead. We introduce a measure so as to know the number of packets receivers need to buffer until they can authenticate the received packets. The number of chains of our model plays a main role in the efficiency of our scheme in terms of loss resistance and overhead. Keywords: Multicast stream authentication, hash chain, signature amortization, web security. [ABSTRACT FROM AUTHOR]

Multimedia information management, which implies all steps from creation and production to distribution and consumption, is a complex and challenging research area. To have a secure and trusted system we need to take into account aspects such as digital rights management (DRM), certification, control and security. As current solutions rely on proprietary architectures and tools, we propose an open architecture, as general as possible and not restricted to a specific standard, which provides trust and rights management in multimedia information systems. We analyse how the elements of the architecture provide trust to the whole value chain by managing multimedia content and digital rights represented using current standards, such as MPEG-21 and OMA DRM, and we compare it with an alternative approach. Then, we illustrate the system operation through a content composition use case, and finally, we present the software tools that we have already developed and the future work. [ABSTRACT FROM AUTHOR]

Digital Rights Management (DRM) enforces the rights of copyright holders and enforces their business models. This imposes restrictions on the way users handle content. These restrictions apply specifically in networked environments. Authorized Domain (AD) DRM concepts remove, or at least reduce, several of these restrictions to a large extent, while at the same time taking into account the content providers' need to limit the proliferation of content. In this paper we describe the design and operation of an Authorized Domain system, which we call the Personal Entertainment Domain (PED). Keywords: Digital Rights Management, DRM, Authorized Domain. [ABSTRACT FROM AUTHOR]

Phishing and Web spoofing have proliferated and become a major nuisance on the Internet. The attacks are difficult to protect against, mainly because they target non-cryptographic components, such as the user or the user-browser interface. This means that cryptographic security protocols, such as the SSL/TLS protocol, do not provide a complete solution to tackle the attacks and must be complemented by additional protection mechanisms. In this paper, we summarize, discuss, and evaluate the effectiveness of such mechanisms against (large-scale) phishing and Web spoofing attacks. Keywords: SSL/TLS, phishing, Web spoofing, visual spoofing. [ABSTRACT FROM AUTHOR]

In a self-healing key distribution scheme a group manager enables a large and dynamic group of users to establish a group key over an unreliable network. The group manager broadcasts in every session some packet of information in order to provide a common key to members of the session group. The goal of self-healing key distribution schemes is that, even if the broadcast is lost in a certain session, the group member can recover the key from the broadcast packets received before and after the session. This approach to key distribution is quite suitable for wireless networks, mobile wireless ad-hoc networks and in several Internet-related settings, where high security requirements need to be satisfied. In this work we provide a generalization of previous definitions in two aspects. The first one is to consider general structures instead of threshold ones to provide more flexible performance to the scheme. The second one is to consider the possibility that a coalition of users sponsor a user outside the group for one session: we give the formal definition of self-healing key distribution schemes with sponsorization, some bounds on the required amount of information. We also give a general construction of a family of self-healing key distribution schemes with sponsorization by means of a linear secret sharing scheme. Our construction differs from previous self-healing key distribution schemes in the fact that the length of the broadcast is almost constant. Finally we analyze the particular case of this general construction when Shamir's secret sharing scheme is used. Keywords: Group key, self-healing, dynamic groups, linear secret sharing schemes, broadcast. [ABSTRACT FROM AUTHOR]

As more and more security-critical computation is done in embedded systems it is also becoming increasingly important to facilitate cryptography in such systems. The Advanced Encryption Standard (AES) specifies one of the most important cryptographic algorithms today and has received a lot of attention from researchers. Most prior work has focused on efficient implementations with throughput as main criterion. However, AES implementations in small and constrained environments require additional factors to be accounted for, such as limited memory and energy supply. In this paper we present an inexpensive extension to a 32-bit general-purpose processor which allows compact and fast AES implementations. We have integrated this extension into the SPARC V8-compatible LEON-2 processor and measured a speedup by a factor of up to 1.43 for encryption and 1.3 for decryption. At the same time the code size has been reduced by 30-40%. Keywords: Advanced Encryption Standard, 32-bit implementation, instruction set extensions, S-box, cache-based side-channel analysis. [ABSTRACT FROM AUTHOR]

Oblivious transfer protocol is a basic building block of various cryptographic constructions. We propose a novel protocol - batch oblivious transfer. It allows efficient computation of multiple instances of oblivious transfer protocols. We apply this protocol to improve the fast simultaneous contract signing protocol, recently proposed in [11], which gains its speed from computation of time-consuming operations in advance. Using batch oblivious transfer, a better efficiency can be achieved. [ABSTRACT FROM AUTHOR]

Authentication, non-repudiation, and digital signatures, require the ability to determine if a data token existed at a certain moment in time when the creator's credentials were valid. Time-stamps are tokens which contain a verifiable cryptographic link between a time value and a data representation. The paper presents some critical aspects of the X.509 Public Key Infrastructure Time Stamp Protocol, trying to suggest some possible improvements to the protocol. Keywords: PKI, security, time-stamp, TSA, PKIX TSP. [ABSTRACT FROM AUTHOR]

For verification and authentication of the video material and recovery of the original video several security mechanisms are required. The security techniques to realize this solution are introduced in [1]: 1 The verification of the integrity is verified by hash functions.2 Authenticity is verified by digital signatures using asymmetric cryptography and hash functions. The introduced scheme from [1] uses RSA signatures. The private key of the digital signature mechanism is used to sign the data and the corresponding public key is used for verification of the encrypted data. If the data can be verified the corresponding private key was used for the digital signature generation and the data seems to be authentic as well integer.3 Furthermore the original content can be reproduced by inverting of the watermark with the well know techniques of Fridrich et al. [2]. Additional secret key cryptography (symmetric crypt function) protects the reproduction. The invertibility is necessary, because we use a digital watermark to embed the authentication message and signature into the media itself. Digital watermark, in this application fragile watermark, changes the data and the original data cannot be reconstructing. To invert the data, the watermark must be removed and the original data reconstructed. The watermark embeds the information into a non visual or acoustical channel of the data after the original data of the channel were compressed and encrypted. The compression realizes the new space for the watermark consisting of the encrypted selected data and security information. [ABSTRACT FROM AUTHOR]

With ubiquitous use of digital cameras, e.g. in mobile phones, privacy is no longer threatened by governments and companies only. A new threat exists by people, who take photos of unaware people with no risk and little cost anywhere in public and private spaces. Fast distribution via online communities and web pages expose an individual's private life to the public. Social and legal measures are taken to deal with this, but they are hardly enforcable. We propose a supportive infrastructure aiming for the distribution channel such that if the picture gets publicly available, the exposed individual has a chance to detect it and take action. [ABSTRACT FROM AUTHOR]

In this work in progress paper we discuss an established as well as a new approache to the use of Gaussian Mixture Models (GMMs) for handwriting biometrics. The technique of GMMs is well explored for the domain of speech processing and we evaluate ways to use them for handwriting biometrics, too. [ABSTRACT FROM AUTHOR]

The statement "What You See Is What You Sign" (WYSIWYS) expresses a functional requirement for digital signatures of electronic documents, in particular when considering legally binding signatures. However this statement is intrinsically wrong. In fact a signer never really sees what he digitally signs, namely the bits of the electronic document, but he sees only one of the possible representations of these bits. This is due to the theory and the technology underlying the actual implementations of the digital signatures. Moreover, while the acronym refers only to the presentation on the signer side, in legal settings the presentation on the recipient side must be also taken into account as well as the relation between the twos. [ABSTRACT FROM AUTHOR]

Citizens interact at regular intervals with municipalities or municipal organizations. Public administrations offer a variety of services like requests/processing of certificates and (local) tax payment. An effective and efficient service provision brings benefits to both municipalities and the involved citizens/customers of a particular service. Due to the fact that exchanged data in forms and documents may contain private or/and sensitive data, it is imperative to introduce security mechanisms that guarantee to citizens a trustworthy means of communication via a network that may be insecure, such as the Internet. Further, cross-border services involve different municipalities and other public authorities in the processes. The described work is derived from research for "eMayor", a project funded by the EU committee. eMayor addresses the specific audience of Small and Medium sized Governmental Organizations (SMGOs) across Europe. The project looks especially at transactions that are performed on a European level. This paper focuses on an architecture for secure policy enforcement within eGovernment platforms, such as the eMayor platform. [ABSTRACT FROM AUTHOR]

Most current watermarking algorithms utilize syntactic features to achieve a good tradeoff between robustness and transparency by using perceptual models. They focus only on a detailed view of the contents, while little attention is paid to define and apply the semantic content features in the watermarking schemes. [ABSTRACT FROM AUTHOR]

In this work, we consider the text data-hiding problem as a particular instance of the well-known Gel'fand-Pinsker problem [1]. The text, where some message is to be hidden, is represented by x and called cover text. Each component xi, i = 1, 2..., N, of x represents one character from this text. Here, we define a character as an element from a given language alphabet (e.g. the latin alphabet {A, B..., Z}). To be more precise, we conceive each character xi as a data structure consisting of multiple component fields (features): name, shape, position, orientation, size, color, etc. [ABSTRACT FROM AUTHOR]

JSteg is a steganographic method for JPEG images that can be viewed as LSB steganography. Recently, we proposed a new principle to detect the use of LSB steganography in digitized vector signals and showed how to apply it to gray-scale images. In this paper, we discuss how to apply it to JPEG images and show some experimental results for the JSteg-like algorithm. [ABSTRACT FROM AUTHOR]

Development of digital communications systems significantly extended possibility to perform covert communications (steganography). This recalls an emerging demand in highly efficient counter-measures, i.e. steganalysis methods. Modern steganography is presented by a broad spectrum of various data-hiding techniques. Therefore development of corresponding steganalysis methods is rather a complex problem and challenging task. Moreover, in many practical steganalysis tasks second Kerckhoff's principle is not applicable because of absence of information about the used steganography method. This motivates to use blind steganalysis, which can be applied to the certain techniques where one can specify at least statistics of the hidden data. This paper focuses on the class of supervised steganalysis techniques developed for the additive steganography, which can be described as y = f(x, s, K) = x + g(s, K), where stego image y is obtained from the cover image x by adding a low-amplitude cover image independent ((1 embedding also known as LSB matching) or cover image dependent (LSB embedding) stego signals that may be also depended on secret stego key K and the secret data s. The function g(.) represents the embedding rule. [ABSTRACT FROM AUTHOR]

Many emerging group oriented and collaborative applications such as audio/video conferences use the peer-to-peer paradigm. Confidentiality is an often demanded feature for such applications, e.g. in business meetings, to provide group privacy. To assure confidentiality in a meeting the partners have to agree upon a common secret key for encrypting their communication. This requires efficient distributed group key exchange protocols. We present the principle of the key distribution protocol TKD which achieves a lower key refreshment delay compared to existing key exchange protocols. [ABSTRACT FROM AUTHOR]

Copyrighted materials are divided into multiple segments and each segment has multiple variations that are differently watermarked and encrypted. The combination of watermark and encryption enables one to identify the actual users (traitors) who have engaged in the piracy. In this paper, we shall present a traitor tracing scheme that can efficiently and flexibly defend against anonymous attacks. [ABSTRACT FROM AUTHOR]

This paper presents a new vulnerability scanning model named as INVUS, which contains aspects of both network and host-based vulnerability scanners. INVUS model has client/server architecture and provides an option to repair the found vulnerabilities by working with the firewall. [ABSTRACT FROM AUTHOR]