Non-repudiation techniques are to ensure any communication taking place between two or more parties will be undeniable. Therefore it is crucial to include digital signatures of the involving parties while the communication is taking place. In medical practices, involved parties include; patient(s), doctor(s), pharmacist(s), who are involved in series of visits, diagnosis, prescriptions, and possible operations. To avoid possible conflicts, deploying non-repudiation techniques help immensely. This thesis considers this issue in a wireless medium and studies the Quality of Service (QoS)/Security requirements in terms of network parameters and performance metrics. In terms of research contributions, this thesis embodies a thorough research on layered and cross-layer QoS and security schemes, in particular, featuring an adaptive Forward Error Correction (FEC) at the application layer, adapting to channel conditions. This leads to a cross layer design, which considers various QoS and security parameters export and import to and from various layers with a special focus on the application layer. The aim of this thesis is to consider a practical implementation and associated complexities of a non-repudiation system, including analytical and experimental testbeds and results. The security schemes are based on Suite-B cryptographic algorithms, including: The Elliptic Curve Diffie-Hellman (ECDH) for key agreement, the Advanced Encryption Standard - Galois/Counter Mode (AES-GCM) for encryption and authentication, the Elliptic Curve Digital Signature Algorithm (ECDSA) for digital signatures, and the Secure Hash Algorithm (SHA) for integrity. A key aspect of Suite-B is the deployment of Elliptic Curve Cryptography (ECC). The non-repudiation aspect of this thesis is based on the Suite-B’s digital signature scheme; ECDSA. The digital signature and the hashing function target the entire multimedia data (i.e., text, video, and voice) and the challenge is to offer such extensive security treatment, while guaranteeing certain Quality of Service settings. These settings include: minimum round trip delay, maximum overhead, and minimum bandwidth allocation.

The Unidata Program Center is an organization working with the University Center for Atmospheric Research (UCAR), in Colorado. It provides a broad variety of meteorological data, which is used by researchers in many real-world applications. This data is obtained from observation stations and distributed to various universities worldwide, using Unidata’s own Internet Data Distribution (IDD) system, and software called the Local Data Manager (LDM). The existing solution for data distribution has many limitations, like high end-toend latency of data delivery, increased bandwidth usage at some nodes, poor scalability for future needs and manual intervention for adjusting to changes or faults in the network topology. Since the data is used in so many applications, the impact of these limitations is often substantial. This thesis removes these limitations by suggesting improvements in the IDD system and the LDM. We present new algorithms for constructing an application-layer data distribution network. This distribution network will form the basis of the improved LDM and the IDD system, and will remove most of the limitations given above. Finally, we perform simulations and show that our algorithms achieve better average end-to-end latency as compared to that of the existing solution. We also compare the performance of our algorithms with a randomized solution. We find that for smaller topologies (where the number of nodes in the system are less than 38) the randomized solution constructs efficient distribution networks. However, if the number of nodes in the system increases (more than 38), our solution constructs efficient distribution networks than the randomized solution. We also evaluate the performance of our algorithms as the number of nodes in the system increases and as the number of faults in the system increases. We find that even if the number of faults in the system increases, the average end-to-end latency decreases, thus showing that the distribution topology does not become inefficient.

Non-repudiation techniques are to ensure any communication taking place between two or more parties will be undeniable. Therefore it is crucial to include digital signatures of the involving parties while the communication is taking place. In medical practices, involved parties include; patient(s), doctor(s), pharmacist(s), who are involved in series of visits, diagnosis, prescriptions, and possible operations. To avoid possible conflicts, deploying non-repudiation techniques help immensely. This thesis considers this issue in a wireless medium and studies the Quality of Service (QoS)/Security requirements in terms of network parameters and performance metrics. In terms of research contributions, this thesis embodies a thorough research on layered and cross-layer QoS and security schemes, in particular, featuring an adaptive Forward Error Correction (FEC) at the application layer, adapting to channel conditions. This leads to a cross layer design, which considers various QoS and security parameters export and import to and from various layers with a special focus on the application layer. The aim of this thesis is to consider a practical implementation and associated complexities of a non-repudiation system, including analytical and experimental testbeds and results. The security schemes are based on Suite-B cryptographic algorithms, including: The Elliptic Curve Diffie-Hellman (ECDH) for key agreement, the Advanced Encryption Standard - Galois/Counter Mode (AES-GCM) for encryption and authentication, the Elliptic Curve Digital Signature Algorithm (ECDSA) for digital signatures, and the Secure Hash Algorithm (SHA) for integrity. A key aspect of Suite-B is the deployment of Elliptic Curve Cryptography (ECC). The non-repudiation aspect of this thesis is based on the Suite-B’s digital signature scheme; ECDSA. The digital signature and the hashing function target the entire multimedia data (i.e., text, video, and voice) and the challenge is to offer such extensive security treatment, while guaranteeing certain Quality of Service settings. These settings include: minimum round trip delay, maximum overhead, and minimum bandwidth allocation.

The Session Initiation Protocol (SIP) was first published in 1999, by the Internet Engineering Task Force (IETF), to be the standard for multimedia transfers. SIP is a peer-to-peer signaling protocol that is capable of initiating, modifying, and terminating media sessions. SIP utilizes existing Internet Protocols (IP) such as Domain Name Service (DNS) and the Session Description Protocol (SDP), allowing it to seamlessly integrate into existing IP networks. As SIP has matured and gained acceptance, its deficiencies when functioning as a multipoint communications protocol have become apparent. SIP currently supports two modes of operation referred to as conferencing and multicasting. Conferencing is the unicast transmission of session information between conference members. Multicasting uses IP multicast to distribute session information. This thesis proposes an extension for the Session Initiation Protocol that improves functionality for multipoint communications. When using conferencing, a SIP user-agent has limited information about the conference it is taking part in. This extension increases the awareness of a SIP node by providing it with complete conference membership information, the ability to detect neighboring node failures, and the ability to automatically repair conference partitions. Signaling for conferencing was defined and integrated into a standard SIP implementation where it was used to demonstrate the above capabilities. Using a prototype implementation, the additional functionality was shown to come at the cost of a modest increase in transaction message size and processing complexity. IP multicast has limited deployment in today's networks reducing the usability of this useful feature. Since IP multicast support is not guaranteed, the use of application layer multicast protocols is proposed to replace the use of IP multicast. An efficient means of negotiating an application layer protocol is proposed as well as the ability to provide the protocol with session information to begin operation. A ring protocol was defined and implemented using the proposed extension. Performance testing revealed that the application layer protocol had slightly higher processing complexity than conferencing, but on average had a smaller transaction message size. / Master of Science

Internet-scale dissemination of streaming contents (e.g. live sport games) is most successfully being provided by Multicast Content Delivery Networks (Multicast CDN). Multicast CDN is composed of dedicated servers placed strategically over the Internet, which forward content from origin site to end users. Multicast CDN delivers huge amount of data traffic, and therefore its major operational cost is the ISP cost for network access. Existing Multicast CDNs route user requests to most suitable server based on application performance, such as network delay, server throughput, Internet path congestion etc., without taking into account the potentially high ISP cost it may incur. Multicast CDNs need to control their ISP cost to remain commercially competitive since ISP cost is the most indicative factor affecting the pricing of their services. In this work, we present novel Multicast CDN Request Routing algorithms that minimize ISP cost while still maintaining good network performance for users. Multicast CDN Request Routing algorithms control majority of traffic assigned to servers and therefore directly impacts the ISP cost. ISP cost and user network performances are orthogonal metrics of performance and in order to balance the trade-off between them we introduce overall delay as a constraint to the Multicast CDN Request Routing algorithm. Multicast CDNs are business customers of ISPs and therefore can independently choose to reduce their bills by considering the ways in which ISPs charge. We have designed Request Routing algorithms that exploit the economy of scale in ISP charging function in assigning users to servers. We have developed Request Routing algorithms that exploit the nature of Percentile-based charging used by ISPs to compute the charging volume for traffic generated at server sites. Multicast CDN can cooperate with ISPs to reduce the operational cost of both the parties. Multicast CDN controls how traffic is redirected on the overlay, and that can conflict with how underlying ISPs want the traffic to be forwarded. We have developed Request Routing algorithms that assign users to servers that are available over cheaper IP routes. This reduces the transmission costs for ISPs and these savings can be transferred onto Multicast CDN.

Over the past few years, a growing attention has been paid to the publish/subscribe (pub/sub) communication paradigm which has become the best model for disseminating information (also called events) through distributed systems on wide-area networks. There are many ways to implement the publish/subscribe system architecture. A common way is publishers and subscribers interact through one or more agents called broker. Broker has to store and management subscriptions, match messages, and efficiently delivery messages to subscribers. It also provides reliability and fault tolerant controlling. Obviously, broker is the most important part of the publish/subscribe system. It is usually required to use a lot of resources such as CPU and memory. In this paper, our publish/subscribe service which implemented by ZeroMQ API could service 10,000 subscribers only cost 3% CPU and 5% memory usage. It is a high performance and low costs publish/subscribe service.

No description available.

Over the last couple of years the rise of application layer Distributed Denial of Service (DDoS) attacks has significantly increased. Because of this, many issues have been raised on how organizations and companies can protect themselves from intrusions and damages against their systems and services. The consequences from these attacks are many, ranging from revenue losses for companies to stolen personal data. As the technologies are evolving, application layer DDoS attacks are becoming more effective and there is not a concrete solution that entirely protects against them. This thesis focuses on the available defense mechanisms and presents a general overview of different types of application layer DDoS attacks and how they are constructed. Moreover this report provides a simulation based on one of the defense mechanisms mentioned, named CALD. The simulation tested two different application layer DDoS attacks and showed that CALD can detect and differentiate between the two attacks. This report can be used as a general information source for application layer DDoS attacks, how to detect them and how to defend against them. Furthermore the simulation can be used as a basis on how well a relatively small-scaled implementation of CALD can detect DDoS attacks on the application layer. / Under de senaste åren har ökningen av Distributed Denial of Service (DDoS) attacker på applikationslagret ökat markant. På grund av detta har många frågor uppkommit om hur organisationer och företag kan skydda sig mot intrång och skador mot sina system och tjänster. Konsekvenserna av dessa attacker är många, allt från intäktsförluster för företag till stulen personlig data. Eftersom tekniken utvecklas, har DDoS attacker på applikationslagret blivit mer effektiva och det finns inte en konkret lösning för att hindra dem. Denna rapport fokuserar på de tillgängliga försvarsmekanismer och presenterar en allmän översikt över olika typer av DDoS-attacker på applikationslagret och hur de är uppbyggda. Dessutom bidrar den här rapporten med en redovisning av en simulering baserad på en av de försvarsmekanismer som nämns i rapporten, CALD. Simuleringen testade två olika attacker på applikationslagret och visar att CALD kan upptäcka och skilja mellan de två attackerna. Denna rapport kan användas som en allmän informationskälla för DDoSattacker på applikationslagret och hur man försvarar sig mot och upptäcker dessa. Vidare kan simuleringen användas som utgångspunkt på hur väl en relativt småskalig implementering av CALD kan upptäcka DDoS-attacker på applikationslagret.

Multimedia applications over the Internet and Internet Protocol Television (IPTV) gain a lot of attention. IPTV has a number of service requirements such as / high bandwidth, scalability, minimum delay, jitter and channel switch time. IP multicast, IMS (IP Multimedia System) Protocol and peer-to-peer approaches are proposed for implementing IPTV. However, IP multicast requires all the routers in the core network to possess multicast capability, IMS does not easily scale and P2P cannot eciently utilize the network resources because of its completely distributed nature. To this end, we propose new application layer multicast protocol Cluster Based Application Layer Multicast IPTV (CALMTV) which combines application layer multicast, scalable video coding and probing techniques to meet IPTV requirements. We present the components and their relevant algorithms and evaluate the performance of CALMTV with ns2 simulations. Our results compared with the published results of other IPTV architectures show that CALMTV has better performance in end-to-end delay and zapping time.

In these few years, gradually Internet develops to wideband, multimedia is being used on video or music. In addition, the use of IP Multicast must be based on the deployment of routers, which is too difficult to arrange. Utilities of Application Layer Multicast is in the middle and just between IP Multicast and Unicast.Therefore, in this paper, Application Layer Multicast is still worth to study it. In this paper, is applied effectively build the Application Layer Multicast. Control through the IP Anycast Technique, we can lower the time for host join the Multicast Tree. Every host can join the nearest cluster. We use the hierarchical cluster-based Method in order to serve more hosts. This concept about cluster can substantially decrease control overhead. The Complete Binary Trees lower the cluster leader¡¦s burden, also phased RTT decided effectively the transit sequence. In Summary, associate techniques with methods, to make up the defects from NICE and I-Zigzag.