An IEEE 802.15.4 security sublayer implementation for CC2420

During the last ten years, the presence of sensor networks in common life has become pervasive and sensor nodes are currently used in many areas of interest. One of the most common radio communication protocol designed for Personal Area Network (PAN) is described by the IEEE 802.15.4 standard, according to which data communication among devices can also be protected on a per frame basis, so making it possible to assure data authenticity and confidentiality, and security mechanisms can be configured in a flexible and effective way. In this thesis work, the IEEE 802.15.4 security sublayer has been implemented. In particular, the TinyOS implementation for the tmote sky mote and the CC2420 chipset have been considered. The main goal of this work is to extend the above mentioned MAC layer implementation in order to make the IEEE 802.15.4 security mechanisms available, that is sending and receiving both ciphered and authenticated frames, by means of the security features provided by the CC2420 chipset. All security data structures and procedures have been implemented, so making it possible to deal with different cryptographic keys usage and retrieval modes. During the development phase, some problems strictly related to computational and memory capacity shortage have been faced and properly addressed. Finally, the implemented security sublayer has been tested and evaluated by means of a simple application, which sends secured packets whose payload changes both in content and size

Performance Evaluation of Security Solutions for Wireless Sensor Networks

In the recent years, wireless communication is involving not only computers, but a multitude of heterogeneous devices. Wireless Sensor Networks (WSNs) contribute to the new paradigm of pervasive computing, and this translates into new requirements for new applications. WSNs are employed not only on their own, but also in Cooperating Objects Systems (COSs), where mobile physical agents share the same environment to fulfill their tasks, either in group or in isolation. Sensor nodes are typically resource constrained devices deployed in unattended, possibly hostile environments. WSNs and COSs are a tempting target for an adversary, since a security infringement may easily translate into a safety one, with possible consequences in terms of damages to things and injures to people. Main security requirements for WSNs are secure communication, key management and secure bootstrapping. Security usually involves resource greedy operations, while sensors are resource constrained devices. This means that security requirements must be satisfied assuring a lightweight impact in terms of memory occupancy, network performance and energy consumption. In this thesis work, we start from a performance evaluation of the security sublayer of the IEEE 802.15.4 standard in terms of memory occupancy, network performance and energy consumption. Then, present and evaluate a solution to a vulnerability of the IEEE 802.15.4 standard that causes a selective Denial of Service attack. Finally, we present PLASA: a modular and reconfigurable security architecture for WSNs. PLASA extends the STaR architecture. STaR is a secure communication module we designed to provide confidentiality and/or authenticity of communications in a trans- parent and flexible manner. PLASA enhances STaR, introducing modules for key management and secure bootstrapping, so providing a complete system that is suitable not only for the WSN, but for the entire COS

On Evaluating the Performance Impact of the IEEE 802.15.4 Security Sub-layer

Nowadays, wireless sensor networks (WSNs) are used in a wide range of application scenarios ranging from structural monitoring to health-care, from surveillance to industrial automation. Most of these applications require forms of secure communication. On the other hand, security has a cost in terms of reduced performance. In this paper we refer to the IEEE 802.15.4 standard and investigate the impact of the 802.15.4 security sub-layer on the WSN performance. Specifically, we analyze the impact that security mechanisms and options, as provided by the standard, have on the overall WSN performance, in terms of latency, goodput, and energy consumption. To this end, we develop an analytical model and a security enabled simulator. We also use a real testbed, based on a complete open-source implementation of the standard, to validate simulation and analytical results, as well as to better understand the limits of the current WSN technology

Sintesi di un isostero del 3,5-dimetil-6-fenil-8-(trifluorometil)-5,6-diidropirazolo[3,4-f][1,2,3,5]tetrazepin-4(3H)-one (CF3-TZP) con potenziale attività biologica

In un precedente lavoro abbiamo mostrato i risultati relativi alla sintesi ed all’attività biologica del CF3-TZP 1[1] (Figura 1). Le attività antiproliferativa e apoptotica del composto 1 sono state testate su differenti linee cellulari, HL60 sensibili, HL60-R (MDR), K562 e K562-R (resistenti al Gleevec®), mostrando un profilo di attività biologica similare sulle cellule sensibili e resistenti nel range di 21-40 µM per l’IC50 e 36-62 µM per l’AC50. L’analisi citofluorimetrica sulle K562 sensibili ha indicato che il composto 1 determina un arresto dose-dipendente del ciclo cellulare in fase G0-G1 nelle prime 24 h di trattamento, mentre nelle successive 24 h si è notato una riduzione del picco G0-G1 ed un incremento del picco apoptotico subG0-G1. Gli incoraggianti risultati biologici ci hanno spinto a continuare gli studi su questa tipologia di molecole sintetizzando l’isostero 2 (Figura 1) attraverso una lunga via di sintesi (15 steps). Attualmente, sono in corso i saggi biologici per valutare le attività antiproliferativa e apoptotica. Bibliografia 1 Maggio, B.; et al, Eur. J. Med. Chem., 2008, 43, 120

Progettazione e sintesi di nuovi derivati 4-chinazolinonici potenziali inibitori della diidrofolato reduttasi

I chinazolinoni sono composti eterociclici azotati che, insieme alle chinazoline, rappresentano degli importanti farmacofori in possesso di un ampio spettro di proprietà biologiche tra cui quella antitumorale. Recentemente sono stati riportati in letteratura dei derivati 4-chinazolinonici in grado di inibire in vitro l’enzima diidrofolato reduttasi (DHFR) con IC50 comprese tra 0.4 e 1.0 µM [1]. Allo scopo di progettare la sintesi di nuovi potenziali inibitori della DHFR, è stato condotto uno studio di modellistica molecolare considerando tale enzima come biotarget. Tale studio ha portato alla selezione di 42 nuovi derivati 4-chinazolinonici (Figura 1). Attualmente, sono stati sintetizzati 20 dei 42 nuovi derivati 4-chinazolinonici, che sono stati saggiati preliminarmente sulla linea cellulare K562. Il derivato più attivo ha mostrato una IC50 di 18 µM. Sono in corso saggi enzimatici per valutare in vitro l’inibizione dell’enzima DHFR. Bibliografia 1 Al-Omary F.A.M.; et al, Bioorganic & Medicinal Chemistry, 2010, 18, 2849

Pirrolomicine che inibiscono la Sortasi A nelle infezioni sostenute da batteri Gram-positivi

La Sortasi A è un enzima di membrana responsabile dell’ancoraggio delle proteine di superficie sulla parete cellulare dei batteri Gram-positivi. Essa è considerata un interessante obiettivo per lo sviluppo di nuovi farmaci anti-infettivi che mirino ad interferire con importanti meccanismi di virulenza Gram-positivi. In un precedente lavoro abbiamo indagato sull’attività antistafilococcica e antibiofilm di alcune Pirrolomicine naturali e sintetiche, composti pirrolici polialogenati attivi su patogeni Gram-positivi, alle concentrazioni di 1.5 e 0.045 µg/mL. I risultati biologici hanno mostrato percentuali di inibizione di biofilm comprese tra 50-80% [1]. Allo scopo di indagare sul loro meccanismo d’azione sono stati condotti studi di modellistica molecolare e saggi di inibizione in vitro sull’enzima Sortasi A (Figura 1). I risultati ottenuti indicano che la Sortasi A potrebbe essere il bersaglio sul quale le Pirrolomicine agiscono, con IC50 comprese tra 130-250 µM, nell’inibizione della formazione di biofilm. Bibliografia 1 Schillaci, D.; et al, Biofouling, 2010, 26, 433

A performance evaluation method for WSNs security

The amount of Wireless Sensor Network applications requiring security is getting higher and higher and also developers that are not security experts are often required to secure their applications. Many times they do it without any consciousness of the security performance trade-off arisen by this operation.In this paper we present a method for performance evaluation of a modular security architecture for WSNs. Our method evaluates the costs that have to be paid when introducing security, in terms of memory occupancy, network performance and energy consumption. Knowing these indexes leads to awareness of security costs and helps in fine tuning of security performance trade-offs. A designer may apply our method to know the impact on performance of the security modules he needs. Also, we present performance data collected by applying our method on the implementation of PLASA, a modular security architecture we have designed and evaluated

A performance evaluation method for WSNs security

The amount of Wireless Sensor Network applications requiring security is getting higher and higher and also developers that are not security experts are often required to secure their applications. Many times they do it without any consciousness of the security performance trade-off arisen by this operation.In this paper we present a method for performance evaluation of a modular security architecture for WSNs. Our method evaluates the costs that have to be paid when introducing security, in terms of memory occupancy, network performance and energy consumption. Knowing these indexes leads to awareness of security costs and helps in fine tuning of security performance trade-offs. A designer may apply our method to know the impact on performance of the security modules he needs. Also, we present performance data collected by applying our method on the implementation of PLASA, a modular security architecture we have designed and evaluated