Mihai Stanciu

Web-service based implementation solution for a network service manager at network provider

The multimedia services over the Internet rapid development require QoS management solutions to be implemented in the actual networks. The Internet traffic is now mostly best effort. Additional QoS control mechanisms need to be defined for data networks to be able to offer high quality multimedia services like video on demand or IPTV. Such mechanisms are QoS routing, resource reservation, admission control, service provisioning. End to end QOS management systems should be defined for implementing such mechanisms. This paper presents a Web-service implementation solution for a network service manager in charge with the inter-domain pSLS negotiation process.

High order sliding mode observers and singular value decomposition in communications

An important issue in communications, in general, and cryptography, in particular, is recovering the information of interest at the reception end. Recent techniques make use of sliding mode observers to achieve this. Another useful method to reconstruct the state space of the transmitter at the receiver end, is the singular value decomposition. Targeting secure communications, the aim of the present paper is to compare the efficiency of the two techniques, when applied to the estimation of the state space of the transmitter at the reception end. For numerical exemplification, a Sprotts jerk-like system was used. The example is taken without loss of generality, being applicable to all differential models expressing the temporal evolution of diode or bipolar-junction transistor based circuits, like the well-known Colpitts oscillator.

Determining chaotic behavior from experimental data: An alternative to the Lyapunov exponents

The present work aims to find an alternative way to the classical Lyapunov exponents of characterizing the chaotic behavior of a system. The procedures that compute Lyapunov exponents use complicated mathematical operations, such as base change and linearization of the investigated system. The main advantage of the proposed procedure is that it can be applied to experimental data records, without knowing the equations that produced the investigated signals. The tridimensional Hénon map is used for exemplification.

Authentication and authorization architecture design for hybrid mesh networks

Nowadays, the definition and integration of the security measures within the communication network infrastructure from its early stages of design represents a common required task. This paper focus on the overall security architecture we designed for hybrid mesh networks (802.11 and 802.16). The main objectives of our security architecture are the authentication and authorization (AA) of devices/users for granting access to the connectivity services. We point out the main design security requirements we addressed and define our IEEE 802.1x-based security architecture. Thereafter, we present the preliminary validation results achieved to date.

Secret speech transmission using a high order sliding mode observer

This paper proposes a chaos-based communication scheme which transmits a secret speech signal. To recover the states of the transmitter and the unknown message, the receiver uses a high order sliding mode observer. Its input is one of the states of the transmitter. The control parameters of the observer constitute the secret key of the transmission. The main aspect in which the present work differs from already known algorithms using sliding-mode observers to recover secret messages embedded in the dynamics of chaotic systems is the nature of the hidden information it applies to. To the knowledge of the authors, no work has yet applied this type of reconstruction method — sliding mode estimators, to recover secret speech signals, but only text and image, included in the evolution of chaotic systems. Numerical simulations are used to find the appropriate parameters for the designed encryption and deciphering. Efficiency and future improvement methods are discussed.

Encrypting Multimedia Data Using Modified Baptista’s Chaos-Based Algorithm

One of the easiest to implement, yet complex, symmetric key chaos-based ciphers is the one proposed by Baptista in 1998. It has attracted much interest from scholars, who underlined its deficiencies and proposed different methods to enhance it. The present paper proposes an additional step in the encryption procedure - a modulo two sum between the binary representations of Baptista’s cryptograms and that of the value of the chaotic logistic map at that very iteration. This results in a flat distribution of the cryptograms. Thus, one of the major drawbacks of Baptista’s cryptosystem, the exponential decay of the repartition of the cyphertext values, is surmounted. The original Baptista’s algorithm is described, the proposed method is exemplified on a short message and its results are discussed when applied on multimedia files.

Steganographic embedding of a secret message in a video flow

The paper presents a steganographic method which hides a secret message in a video flow. The secret message represents the result of a chaos-based encryption scheme. One of the flaws which make the algorithm unpractical for real-time applications is that, while the elements of the plain-message are represented using 8 bits (ASCII characters) the corresponding encrypted values need to be represented using 16 bits. Since the pixels of a typical image are represented using 24 bits (8 bits for each color component), each encrypted character fits in only one pixel. Moreover, since the resolution of today’s video materials is very large, the pixel previously established to carry in its evolution the hidden content will not be obvious to unaware spectators, but only to the one which knows its coordinates. In addition to the steganographic procedure, the work presents preliminary results on the degree of pseudo-randomness of video flows. The study is based upon the idea behind Lyapunov exponents. The evolution of two pixels which initially differ only by the minimum possible value (the color representation’s resolution) is followed for a large number of video frames. The distance between such points, for pseudo-random behavior, is known to evolve over time in a Gaussian manner. A Kolmogorov-Smirnov statistic is computed and illustrated in order to conclude over the provenience of the data series representing the evolution of the distance between the two initially neighboring pixels from a standard normal law.

Functionality and Scalability Validation for an End to End QoS Management System

This paper presents the validation of an end-to-end QoS integrated management system in a multidomain test-bed environment. The integrated management system was designed and implemented in the framework of the ENTHRONE European project. This paper focuses on the network service management validation at both the Service Provide and Network Provider The Network Service Management is based the SLS management: in the core network the pSLS management is used to deal with users aggregated services, while cSLS management is used to deal with individual users services. Both functionality and scalability tests for SLS management are presented.