Information theoretic clustering, long-range correlation, power-law scaling and self-similarity concepts have been broadly adopted for characterizing genomic features such as nucleotide composition, flexibility and bending. In this work, the 24 chromosomes of the human pangenome minigraphs, recently assembled by the Human Pangenome Reference Consortium (HPRC), are investigated to check to what extent self-similarity and scaling features are preserved in comparison to the reference linear sequences of the T2T-CHM13 individual. By taking the nucleotide self-similarity of the reference chromosomes as benchmark, it is shown that the pangenome minigraph segments exhibit lower self-similarity of the nucleotide composition compared to the linear sequence. The proposed information measures can be adopted to quantify the nucleotide self-similarity patterns and complement standard alignment techniques towards the coherent definition of the genomic profile of each species.

In the vision of the Internet of Things (IoT), objects become smart by aggregating in a network and exchanging information. Thanks to this shared knowledge, the objects can interact for performing advanced tasks. The obtrusiveness of the services is guaranteed by the mobility of the smart objects. For example, mobile sensors are used to follow dynamic phenomena, whereas smartphones and wearable devices are always accessible to the user. The interaction among the smart devices can be described by means of a graph, where nodes, representing IoT objects, are linked if they can communicate. This paper studies the node degree (i.e., the number of links of the node) in a graph developed for describing heterogeneous wireless networks. With respect to previous work, the mobility of the network, which can change the degree of every node, is considered for the first time. Formulas for the degree distribution and the average degree are theoretically computed and then validated with simulations. In particular, as a case study the proposed formulas are applied considering IoT objects following the random waypoint model, one of the most common mobility models.

Air pollution, in particular due to particulate matter, is considered a critical issue, and it is receiving ever growing attention. Environmental monitoring is not limited to the outdoor case in crowded cities, but it is also usefully applied to indoor cases such as factories and offices, or in indoor/outdoor mixed case, such as construction sites or in general industrial plants. This paper describes the case study of an environmental monitoring system, which is compliant with Internet of Things domain. In particular it is suitable for indoor/outdoor industrial applications focused on Particulate Matter measurements. In order to create a reference model, a PM10/PM2.5 sensor not yet tested in literature is used, the Honeywell HPMA115S0-XXX. Four PM10/PM2.5 sensors are used together to test repeatability. This device turned out to be effective in esteeming the level of pollution using low cost sensors, as an alternative to expensive and not portable professional devices. The implementation proposed in this paper is able to give high R values of linear regression, guaranteeing at the same time low cost in terms of hardware and low power consumption.

The majority of security systems for wireless sensor networks are based on symmetric encryption. The main open issue for these approaches concerns the establishment of symmetric keys. A promising key distribution technique is the random predistribution of secret keys. Despite its effectiveness, this approach presents considerable memory overheads, in contrast with the limited resources of wireless sensor networks. In this paper, an in-depth analytical study is conducted on the state-of-the-art key distribution schemes based on random predistribution. A new protocol, called q-s-composite, is proposed in order to exploit the best features of random predistribution and to improve it with lower requirements. The main novelties of q-s-composite are represented by the organization of the secret material that allows a storing reduction, by the proposed technique for pairwise key generation, and by the limited number of predistributed keys used in the generation of a pairwise key. A comparative analysis demonstrates that the proposed approach provides a higher level of security than the state-of-the-art schemes.

Symmetric encryption is the most widely adopted security solution for wireless sensor networks. The main open issue in this context is represented by the establishment of symmetric keys. Although many key management schemes have been proposed in order to guarantee a high security level, a solution without weaknesses does not yet exist. An important class of key management schemes is based on a transitory master key (MK). In this approach, a global secret is used during the initialization phase to generate pair-wise keys, and it is deleted during the working phase. However, if an adversary compromises a node before the deletion of the MK, the security of the whole network is compromised. In this paper, a new key negotiation routine is proposed. The new routine is integrated with a well-known key computation mechanism based on a transitory master secret. The goal of the proposed approach is to reduce the time required for the initialization phase, thus reducing the probability that the master secret is compromised. This goal is achieved by splitting the initialization phase in hierarchical subphases with an increasing level of security. An experimental analysis demonstrates that the proposed scheme provides a significant reduction in the time required before deleting the transitory secret material, thus increasing the overall security level. Moreover, the proposed scheme allows to add new nodes after the first deployment with a suited routine able to complete the key establishment in the same time as for the initial deployment.

Wireless sensor networks offer benefits in several applications but are vulnerable to various security threats, such as eavesdropping and hardware tampering. In order to reach secure communications among nodes, many approaches employ symmetric encryption. Several key management schemes have been proposed in order to establish symmetric keys. The paper presents an innovative key management scheme called random seed distribution with transitory master key, which adopts the random distribution of secret material and a transitory master key used to generate pairwise keys. The proposed approach addresses the main drawbacks of the previous approaches based on these techniques. Moreover, it overperforms the state-of-the-art protocols by providing always a high security level.

In a random sector graph, the presence of an edge between two nodes depends on their distance and spatial orientation. This kind of graph is widely used for modeling wireless sensor networks where communication among nodes is directional. In particular, it is applied to describe both the radio frequency transmission among nodes equipped with directional antennas and the line-of-sight transmission in optical sensor networks. Important properties of a wireless sensor network, such as connectivity and coverage, can be investigated by studying the degree of the nodes of the corresponding random sector graph. In detail, the in-degree value represents the number of incoming edges, whereas the out-degree considers the outgoing edges. This paper mathematically characterizes the average degree of a random sector graph and the probability distributions of the in-degree and out-degree of the nodes. Furthermore, it derives the coverage probability of the network. All the formulas are validated through extensive simulations, showing an excellent match between theoretical results and experimental data.

Recent studies have demonstrated the importance of protecting the hardware implementations of cryptographic functions against side channel and fault attacks. In last years, very efficient implementations of modular arithmetic have been done in RNS (RSA, ECC, pairings) as well on FPGA as on GPU. Thus the protection of RNS Montgomery modular multiplication is a crucial issue. For that purpose, some techniques have been proposed to protect this RNS operation against side channel analysis. Nevertheless, there are still no effective and generic approaches for the detection of fault injection, which would be additionnally compatible with a leak resistant arithmetic. This paper proposes a new RNS Montgomery multiplication algorithm with fault detection capability. A mathematical analysis demonstrates the validity of the proposed approach. Moreover, an architecture that implements the proposed algorithm is presented. A comparative analysis shows that the introduction of the proposed fault detection technique requires only a limited increase in area.

When numerous RFID readers are placed in the same area, they may interfere with each other due to the reader collision problem. In recent years, many studies have been presented to address the reader collision problem. However, there is no consonance on the interference model to use in the analysis of the protocols. The main adopted models are the single interference model, which is simple and fast, but only considers the readers within a threshold distance, and the additive interference model, which sums the interferences of all the concurrent interrogations. Recent studies have shown that the single interference model cannot detect a relevant part of the possible collisions detected by the additive one. This paper analyzes and compares the network performance of an RFID system by applying both the models. Considering two proposed scenarios, the performance of the two models are evaluated and presented.

Dense passive radio frequency identification (RFID) systems are particularly susceptible to reader collision problems, categorized by reader-to-tag and reader-to-reader collisions. Both may degrade the system performance decreasing the number of identified tags per time unit. Although many proposals have been suggested to avoid or handle these collisions, most of them are not compatible with current standards and regulations, require extra hardware and do not make an efficient use of the network resources. This paper proposes the Geometric Distribution Reader Anti-collision (GDRA), a new centralized scheduler that exploits the Sift geometric probability distribution function to minimize reader collision problems. GDRA provides higher throughput than the state-of-the-art proposals for dense reader environments and, unlike the majority of previous works, GDRA is compliant with the EPCglobal standard and ETSI EN 302 208 regulation, and can be implemented in real RFID systems without extra hardware.

The reader-to-reader collision problem represents a research topic of great recent interest for the radio frequency identification (RFID) technology. Among the state-of-the-art anticollision protocols, the ones that provide high throughput often have special requirements, such as extra hardware. This study investigates new high throughput solutions for static RFID networks without additional requirements. In this paper, two contributions are presented: a new configuration, called Killer, and a new protocol, called distributed color noncooperative selection (DCNS). The proposed configuration generates selfish behavior, thereby increasing channel utilization and throughput. DCNS fully exploits the Killer configuration and provides new features, such as dynamic priority management, which modifies the performance of the RFID readers when it is requested. Simulations have been conducted in order to analyze the effects of the innovations proposed. The proposed approach is especially suitable for low-cost applications with a priority not uniformly distributed among readers. The experimental analysis has shown that DCNS provides a greater throughput than the state-of-the-art protocols, even those with additional requirements (e.g., 16 percent better than NFRA).

The modular exponentiation on large numbers is computationally intensive. An effective way for performing this operation consists in using Montgomery exponentiation in the Residue Number System (RNS). This paper presents an algorithmic and architectural study of such exponentiation approach. From the algorithmic point of view, new and state-of-the-art opportunities that come from the reorganization of operations and precomputations are considered. From the architectural perspective, the design opportunities offered by well-known computer arithmetic techniques are studied, with the aim of developing an efficient arithmetic cell architecture. Furthermore, since the use of efficient RNS bases with a low Hamming weight are being considered with ever more interest, four additional cell architectures specifically tailored to these bases are developed and the tradeoff between benefits and drawbacks is carefully explored. An overall comparison among all the considered algorithmic approaches and cell architectures is presented, with the aim of providing the reader with an extensive overview of the Montgomery exponentiation opportunities in RNS.

Supply chain is a typical scenario of exploiting Radio Frequency Identification (RFID) technology. Its growing use in all the supply chain areas makes the presence of many close RFID readers more common. In such environment, interferences among readers are critical. Many protocols have been proposed to reduce reader-to-reader collisions. Experimental data showed that the Neighbor Friendly Reader Anticollision (NFRA) protocol (IEEE Trans. Ind. Electron., vol. 56, no. 7, pp. 2326-2336, July 2009) maximizes the network throughput. However, it does not take into account the delay between the request and the granting of query tags, causing delays for some readers. This paper proposes two approaches to increase the fairness and ensure a high throughput for each reader. A theoretical analysis, supported by experimental simulations, demonstrates the improvements achieved.

The hardware implementation of modular exponentiation for very large integers is a well-known topic in digital arithmetic. An effective approach for obtaining parallel and carry-free implementations consists in using the Montgomery exponentiation algorithm and executing the necessary operations in RNS. Two efficient methods for performing the RNS Montgomery exponentiation have been proposed by Kawamura et al. and by Bajard and Imbert. The above approaches mainly differ in the algorithm used for implementing the base extension. This paper presents a modified RNS Montgomery exponentiation algorithm, where several multiplications are moved outside the main execution loop and replaced by an effective pre-processing stage producing a significant saving on the overall delay with respect to state-of-the-art approaches. Since the proposed modification should be applied to both of the above algorithms, two versions are specifically discussed.

Nowadays, several kinds of applications based on Radio Frequency Identification (RFID) employ a large number of tags and readers, involving collision problems. A relevant group of reader-to-reader anti-collision protocols are based on time division. Normally these protocols do not require special readers or additional entities; their main challenge is the collision resolution, since after a collision, readers have to choose a new time slot trying to avoid new collisions.It is observed that after a collision, its slot is often unoccupied, therefore this paper proposes to introduce the slot change probability as an additional parameter, in order to reduce the number of readers that change slot and the number of colliding transmissions. A new version of Distributed Color Selection (DCS) is presented, analyzed and compared with well-known protocols based on time division. The simulation analysis shows that the average time required to transmit may be reduced by over 10%.

In this paper an agri-food traceability system based on public key cryptography and Radio Frequency Identification (RFID) technology is proposed. In order to guarantee safety in food, an efficient tracking and tracing system is required. RFID devices allow recording all useful information for traceability directly on the commodity. The security issues are discussed and two different methods based on public cryptography are proposed and evaluated. The first algorithm uses a nested RSA based structure to improve security, while the second also provides authenticity of data. An experimental analysis demonstrated that the proposed system is well suitable on PDAs too.

RFID technology increases rapidly its applicability in new areas of interest without guaranteeing security and privacy issues. This paper presents a new architecture of an RFID transponder with cryptographic capabilities. Other than being compatible with the EPC Class-1 Gen-2 communication protocol, our tag implements an asymmetric ciphering module that proved useful in authentication and anti-counterfeit schemes, particularly critical in many application fields. Experimental results concerning area requirements and power consumption indicate its feasibility.