Search

Summary: The widespread use of Internet of Things devices has increased the demand for lower cost and more efficient lightweight ciphers. However, there is a difficult trade‐off between cost and efficiency for lightweight block ciphers. The optimizations of area and throughput are important for some constrained environments. This paper proposes two novel hardware architectures for the LILLIPUT cipher. In the novel low area structure, a new permutation layer is provided for LILLIPUT. The relationship between encryption algorithm and key scheduling algorithm is utilized to achieve optimal sharing among components, which significantly reduces hardware area. The experimental results show that the number of XOR gates and S‐boxes required for low area optimization is reduced by 52 and 8, respectively. The total area is reduced by about 18%. For high throughput structure, this paper provides 2‐round, 5‐round, and 15‐round loop unrolling designs for LILLIPUT to improve throughput. The experimental results show that the throughput of the 5‐round loop unrolling structure reaches a good level, which is relatively the most cost‐effective. In practical application, ciphers can be unrolled implementations according to the needs of devices to improve the execution speed, which can greatly reduce the execution time and complexity of the algorithm. [ABSTRACT FROM AUTHOR]

With the rising incidence of various diseases in China and the constant development of the pharmaceutical industry, there is a growing demand for floxacin-type antibiotics. Due to the large-scale production and high cost of waste treatment, the parent drug and its metabolites constantly enter the water environment through domestic sewage, production wastewater, and other pathways. In recent years, the pollution of the aquatic environment by floxacin has become increasingly serious, making the technology to degrade floxacin in the aquatic environment a research hotspot in the field of environmental science. Metal–organic frameworks (MOFs), as a new type of porous material, have attracted much attention in recent years. In this paper, four photocatalytic materials, MIL-53(Fe), NH2-MIL-53(Fe), MIL-100(Fe), and g-C3N4, were synthesised and applied to the study of the removal of ofloxacin and enrofloxacin. Among them, the MIL-100(Fe) material exhibited the best photocatalytic effect. The degradation efficiency of ofloxacin reached 95.1% after 3 h under visible light, while enrofloxacin was basically completely degraded. The effects of different materials on the visible photocatalytic degradation of the floxacin were investigated. Furthermore, the photocatalytic mechanism of enrofloxacin and ofloxacin was revealed by the use of three trappers (▪O2−, h+, and ▪OH), demonstrating that the role of ▪O2− promoted the degradation effect of the materials under photocatalysis. [ABSTRACT FROM AUTHOR]

Smart door locks pose a large number of threats such as network attacks. Its storage area and power of cipher are severely limited because the wireless nodes of smart door locks are mostly battery‐powered. Therefore, effective security solutions are urgently needed. In this paper, a new lightweight block cipher with low power named LPHD is proposed to ensure the security of the master control chip of the smart door lock terminal. We design a scheme of low power S‐box and construct the two‐stage permutation layer (TP structure) suitable for LPHD by filtering the sets of 8‐bit permutations. LPHD proposes a variant of the 8‐branch generalized Feistel structure (GFS) to realize that the bits of all branches are affected in one encryption round. The problem of slow diffusion in the standard Feistel structure is solved. The key schedule adopts the nonlinear design and reuses the encryption process of LPHD. It improves the security of the cipher and reduces hardware overhead. Moreover, we evaluate the hardware implementation and security of LPHD. The results show that LPHD for the unified encryption and decryption circuits requires only 1276 Gate Equivalents (GEs) and 1.914 μ$$ \upmu $$W on UMC 0.18 μ$$ \upmu $$m, which is better than other lightweight block ciphers such as SKINNY, PRESENT, and IVLBC. In summary, LPHD provides sufficient security for the master control chip of the smart door lock terminal. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, an inverse problem of constructing a linear n degree of freedom mass-spring system from part of its physical parameters and part of modality of its maximal or minimal natural frequencies is considered. The solvability and the expression of the solution is derived. The numerical algorithms and some numerical examples are given. [Copyright &y& Elsevier]

The low-latency property is becoming increasingly crucial in response to the demand for data processing in the Internet of Things (IoT) environment, especially in lightweight cryptography. A low-latency lightweight block cipher called LTLBC is proposed in this paper. In particular, we propose a hybrid approach of word-wise involutive mapping and a bit-wise permutation, with careful selection of the shift and permutation parameters. This scheme enables LTLBC to achieve better diffusion than Midori and MANTIS. Also, a 4×4\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$4\times 4$$\end{document} S-box which is constructed through a gate-level bottom-up circuit search has good security and latency characteristics. LTLBC mainly focuses on the hardware environment of fully unrolled architecture. LTLBC achieves a minimum latency of around 4.73 ns, with a total area of only 10007.6 μm2\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\mu m^2$$\end{document} based on NanGate 45nm technology. The comprehensive safety analysis shows LTLBC has sufficient redundancy rounds to resist attacks, such as differential cryptanalysis, linear cryptanalysis, impossible differential cryptanalysis, etc. [ABSTRACT FROM AUTHOR]

This paper concerns about the regularity criteria for the three-dimensional Navier–Stokes equations. By establishing a more subtle estimate of the crucial convective term in Navier–Stokes equations, we improve [4] and [10] a lot. [ABSTRACT FROM AUTHOR]

Lightweight block ciphers are important for implementing security services on constrained devices today. In this paper, we propose a novel ultra-lightweight block cipher DULBC based on a dynamic SPN structure. The round function of DULBC adopts an unfixed F-function and a bit-based permutation. The choice of the F-function depends on 2 bits of the round keys. This means the encryption process of the cipher is uncertain and its security is greatly improved. Also, a strong 4 × 4 S-box with fewer logic gates is proposed, which costs low hardware resources and ensures excellent performances. We have conducted FPGA implementation and ASIC implementation on DULBC. The throughput of DULBC-80/128 is 555.03/443.84 Mbps and the area of the 16-bit serial architecture of DULBC-80/128 is 1075/1351 GEs, respectively. DULBC is secure and efficient according to our experiments and comparisons. • A novel lightweight block cipher with dynamic structure to improve security and privacy. • Performance of the 4 × 4 S-box with fewer logic gates is even better compared with the isomorphic S-boxes. • High throughput and low area consumption in hardware implementation. [ABSTRACT FROM AUTHOR]

In this paper we develop a fast multiscale Galerkin method solving ill-posed integral equations with not exactly given input data via Tikhonov regularization. The method leads to fast solutions of discrete Tikhonov regularization. The convergence rates of the Tikhonov regularization are achieved by using a modified discrepancy principle. Finally, numerical experiments are given to illustrate the efficiency of the method. [ABSTRACT FROM AUTHOR]

To toughen the Al 2 O 3 matrix ceramic materials, Al 2 O 3 /(W, Ti)C/graphene multi-phase composite ceramic materials were fabricated via hot pressing. The effects of the graphene nanoplates (GNPs) content on microstructure and mechanical properties were investigated. Results showed that the fracture toughness and flexural strength of the composite added with just 0.2 wt% GNPs were markedly improved by about 35.3% (~ 7.78 MPa m 1/2 ) and 49% (~ 608.54 MPa) respectively compared with the specimens without GNPs while the hardness was kept about 24.22 GPa. However, the mechanical properties degrade with the further increase of GNPs’ content owing to the increased defects caused by agglomeration of GNPs. Synergistic toughening effects of (W, Ti)C and GNPs played an essential role in improving the fracture toughness of composites. By analyzing the microstructures of fractured surface and indentation cracks, besides GNPs pull-out, crack deflection, crack bridging, crack branching and crack arrest, new toughening mechanisms such as break of GNPs and crack guiding were also identified. Furthermore, interface stress can be controlled by means of stagger distributed strong and weak bonding interfaces correlated with the distribution of GNPs. [ABSTRACT FROM AUTHOR]

Cationic metal ion-coordinated N-diisopropyloxyphosphoryl dipeptides (DIPP-dipeptides) were analyzed by electrospray ionization multistage tandem mass spectrometry (ESI-MS). Two novel rearrangement reactions with hydroxyl oxygen or carbonyl oxygen migrations were observed in ESI-MS/MS of the metallic adducts of DIPP-dipeptides, but not for the corresponding protonated DIPP-dipeptides. The possible oxygen migration mechanisms were elucidated through a combination of MS/MS experiments, isotope (O, N, and H) labeling, accurate mass measurements, and density functional theory (DFT) calculations at the B3LYP/6-31 G(d) level. It was found that lithium and sodium cations catalyze the carbonyl oxygen migration more efficiently than does potassium and participation through a cyclic phosphoryl intermediate. In addition, dipeptides having a C-terminal hydroxyl or aromatic amino acid residue show a more favorable rearrangement through carbonyl oxygen migration, which may be due to metal cation stabilization by the donation of lone pair of the hydroxyl oxygen or aromatic π-electrons of the C-terminal amino acid residue, respectively. It was further shown that the metal ions, namely lithium, sodium, and potassium cations, could play a novel directing role for the migration of hydroxyl or carbonyl oxygen in the gas phase. This discovery suggests that interactions between phosphorylated biomolecules and proteins might involve the assistance of metal ions to coordinate the phosphoryl oxygen and protein side chains to achieve molecular recognition. [ABSTRACT FROM AUTHOR]