Derived categories of the Cayley plane and the coadjoint Grassmannian of type F

in Transformation Groups (2021)

Curating Online Mathematical Resources

in Notices of the American Mathematical Society (2021), 69(9), 1524--1527

An Overview of Information-Theoretic Secrecy Analysis over Classical Wiretap Fading Channels

in EURASIP Journal on Wireless Communications and Networking (2021)

An alternative or supplementary approach named as physical layer security has been recently proposed to afford an extra security layer on top of the conventional cryptography technique. In this paper, an ... [more ▼]

An alternative or supplementary approach named as physical layer security has been recently proposed to afford an extra security layer on top of the conventional cryptography technique. In this paper, an overview of secrecy performance investigations over the classic Alice-Bob-Eve wiretap fading channels is conducted. On the basis of the classic wiretap channel model, we have comprehensively listed and thereafter compared the existing works on physical layer secrecy analysis considering the small-scale, large-scale, composite, and cascaded fading channel models. Exact secrecy metrics expressions, including secrecy outage probability (SOP), the probability of non-zero secrecy capacity (PNZ), and average secrecy capacity (ASC), and secrecy bounds, including the lower bound of SOP and ergodic secrecy capacity, are presented. In order to encompass the aforementioned four kinds of fading channel models with a more generic and flexible distribution, the mixture gamma (MG), mixture of Gaussian (MoG), and Fox’s H- function distributions are three useful candidates to largely include the above-mentioned four kinds of fading channel models. It is shown that all they are flexible and general when assisting the secrecy analysis to obtain closed-form expressions. Their advantages and limitations are also highlighted. Conclusively, these three approaches are proven to provide a unified secrecy analysis framework and can cover all types of independent wiretap fading channel models. Apart from those, revisiting the existing secrecy enhancement techniques based on our system configuration, the on-off transmission scheme, artificial noise (AN) & artificial fast fading (AFF), jamming approach, antenna selection, and security region are presented. [less ▲]

Attitude Task Allocation and Control in a Swarm of Magnetically Controlled CubeSats

in CDSR 2021 conference proceedings, 8th International Conference on Control, Dynamic Systems, and Robotics (CDSR'21) (2021)

The paper delineates the magnetic controller gains tuning procedure for an active magnetic attitude control system of a CubeSat in the ISS orbit. The optimization is conducted for arbitrary required ... [more ▼]

The paper delineates the magnetic controller gains tuning procedure for an active magnetic attitude control system of a CubeSat in the ISS orbit. The optimization is conducted for arbitrary required attitude given in the orbital reference frame of the spacecraft. The study has been conducted as a part of the Skoltech University project to deploy a swarm of 3U CubeSats for collective gamma-ray bursts detection, which requires the satellites' coordinated attitude control. We consider four identical CubeSats exhibiting swarm behaviour by optimal attitude task allocation on receipt of a command from the mission control center. The first part of this study shows how to obtain the controller gains via linearization of the spacecraft rotational dynamics in the vicinity of the required attitude regime and subsequent numerical optimization (carried out in terms of Floquet theory). The second part shows the collective attitude control scenario. The task of the swarm is to ensure maximum sky coverage around a principal direction uplinked to the spacecraft. The task extends to ensuring the maximum collective stability of the swarm through implementing the optimization algorithm. [less ▲]

Cryptanalysis of a Dynamic Universal Accumulator over Bilinear Groups

in Topics in Cryptology – CT-RSA 2021 (2021)

In this paper we cryptanalyse the two accumulator variants proposed by Au et al., which we call the alpha-based construction and the common reference string-based (CRS-based) construction. We show that if ... [more ▼]

In this paper we cryptanalyse the two accumulator variants proposed by Au et al., which we call the alpha-based construction and the common reference string-based (CRS-based) construction. We show that if non-membership witnesses are issued according to the alpha-based construction, an attacker that has access to multiple witnesses is able to efficiently recover the secret accumulator parameter alpha and completely break its security. More precisely, if p is the order of the underlying bilinear group, the knowledge of O(log p log log p) non-membership witnesses permits to successfully recover alpha. Further optimizations and different attack scenarios allow to reduce the number of required witnesses to O(log p), together with practical attack complexity. Moreover, we show that accumulator's collision resistance can be broken if just one of these non-membership witnesses is known to the attacker. We then show how all these attacks for the alpha-based construction can be easily prevented by using instead a corrected expression for witnesses. Although outside the original security model assumed by Au \etal but motivated by some possible concrete application of the scheme where the Manager must have exclusive rights for issuing witnesses (e.g. white/black list based authentication mechanisms), we show that if non-membership witnesses are issued using the CRS-based construction and the CRS is kept secret by the Manager, an attacker accessing multiple witnesses can reconstruct the CRS and compute witnesses for arbitrary new elements. In particular, if the accumulator is initialized by adding m secret elements, the knowledge of m non-membership witnesses allows to succeed in such attack. [less ▲]

Bücherschau

in Shakespeare Jahrbuch (2021), 157

BURST: a benchmarking platform for uniform random sampling techniques

in SPLC '21: 25th ACM International Systems and Software Product Line Conference, Leicester, United Kindom, September 6-11, 2021, Volume B (2021)

Wegweisende Themen in Fort- und Weiterbildung

in KiTa aktuell HRS - Fachzeitschrift für Leitungen, Fachkräfte und Träger der Kindertagesbetreuung (2021), 29(12), 281

Un arrêt sans dire droit

in Journal des Tribunaux (2021)

Factoring Primes to Factor Moduli: Backdooring and Distributed Generation of Semiprimes

E-print/Working paper (2021)