Key Length Research Articles

High-performance thin-film lithium niobate electro-optic modulator based on etching slot andultrathin silicon film.

An electro-optic modulator (EOM) is an indispensable component to connect the electric and optical fields. Here, we propose a high-performance, thin-film lithium niobate-based EOM, where the modulation waveguide is formed by an etching slot on the lithium niobate film and the deposit of an ultrathin silicon film in the slot region. Therefore, a small mode size and high mode energy can be simultaneously achieved in the LN region with a high EO coefficient, which will be beneficial to increase the EO overlap and gradually decrease in the mode size. Further, we employed a waveguide structure to construct a typical Mach-Zehnder interference-type EOM. According to the requirements of high-speed traveling wave modulation, we conduct the index matching, impedance matching, and low-loss operation. From the results, the key half-wave voltage length product and 3dB modulation bandwidth are, respectively, 1.45Vcm and 119GHz in a modulation length of 4mm. Moreover, a larger 3dB bandwidth also can be achieved by shortening the modulation length. Therefore, we believe the proposed waveguide structure and EOM will provide new ways to enhance the performance of LNOI-based EOMs.

Orbit design of satellite quantum key distribution constellations in different ground stations networks

In the field of Cryptography, Quantum Key Distribution (QKD) is an application of Quantum Information theory that obtained a great deal of attention in recent years. It allows to establish secret keys between two or more parties, in a much safer way than that implemented by classic cryptography (based on discrete logarithms and factorization of prime numbers). The most promising way of realizing a QKD network (especially over great distances) in the near future is by a constellation of satellites. This paper considers the problem of optimizing the orbits of the satellites in order to maximize the minimum key length shared in a network of ground stations over a fixed amount of time. Different networks of stations are considered and the influence of their geographical disposition on the design and the performance index is highlighted. The networks considered are: a global constellation, a regional European constellation, and two in which there are groups of stations in two different narrow bands of latitude. The effect of Inter-satellite links is then taken into account and how, in some cases, they can improve the performances. Finally the daily performance of the considered constellations are analyzed.

Comparative Analysis of Ciphertext Enlargement on Generalization of the ElGamal and Multi-factor RSA

Information and communication security has become more crucial and has become a new problem in relation to security, accessibility, data management, and other information policy challenges as a result of how easy it is for all users to use communication media. One of the fields of science that has a technique or art for disguising the data sent by the sender to the recipient with the aim of maintaining the confidentiality of the data is called cryptography. In determining better cryptographic algorithms for data security systems, in addition to considering strength, key length and ciphertext enlargement are also important factors to consider. Therefore, in this study, we attempted to compare the ciphertext magnification of the generalization of the ElGamal and multi-factor RSA algorithms by utilizing the same key length. Generalization of the ElGamal and Multi-factor RSA are both asymmetric algorithms that have public and private key pairs for encryption and decryption. However, at the level of security, the RSA algorithm is based on the difficulty of finding large integer factors into two prime factors. In contrast to the ElGamal algorithm, security is based on the difficulty of calculating the discrete logarithm of a large prime modulus. The results of the comparison algorithm carried out are represented in the form of a table containing the plaintext, key length, and size of the data.

A turbo‐based encryption and coding scheme for multiple‐input multiple‐output orthogonal frequency division multiplexing wireless communication systems affected by Doppler frequency offset

AbstractMultiple‐Input Multiple‐Output Orthogonal Frequency Division Multiplexing (MIMO‐OFDM) is an essential technology in the wireless communication system. However, its performance is significantly affected by Carrier Frequency Offset (CFO), which leads to inter‐carrier interference (ICI). The CFO estimation and compensation techniques are used to mitigate the Doppler effect. In addition, the confidentiality of data is a key factor of the system. This paper proposes a Turbo‐based encryption and coding scheme to improve reliability and security for the MIMO‐OFDM wireless communication systems affected by the Doppler frequency offset. In our proposed scheme, the secret key is produced from channel parameters between legitimate users and it is used as a seed for generating a pseudo‐random bit sequence using an Advanced Encryption Standard (AES) generator with variable key lengths. The Turbo code's puncturing mechanism is controlled by this pseudo‐random bit sequence. The proposed method is applied to the system with different modulation schemes through the Rayleigh channel. The simulation results show that the system affected by the Doppler effect would obtain the best performance when using the highest key length of the AES generator, the BPSK, and a great number of receive antennas. Furthermore, the proposed solution outperforms several previous approaches for the MIMO‐OFDM systems.

Comparative Analysis of Encryption Algorithms

Purpose: Encryption algorithm allows users to extend the assurance found in the physical world to the electronic world in the carrying out of our day-to-day activities. This research attempts to make a comparative evaluation of two encryption algorithms (Advanced Encryption Standard (AES) and Rivest Shamir Algorithm (RSA) in order to ascertain the most reliable in terms of their encryption time, decryption time, Key length, and cipher length.
 Methodology: Java programming was used for the development and Mongo Db to generate data parsing.
 Findings: The results obtained from the development revealed that AES is considered more efficient because it uses lesser time for encryption and decryption, reduces cipher and key length as compared with RSA which consumes longer encryption and decryption time, and increases cipher and key length. Excel package was also used to display the pictorial representation of the comparison between these algorithms.
 Recommendation: Advanced encryption standard is recommended for security-based application developers because of the small time of encryption and decryption.

Key Generation Technique Based on Channel Characteristics for MIMO-OFDM Wireless Communication Systems

Dynamic secret key generation from wireless channel characteristics is a promising technique for physical layer security. One of the important issues in this field is extending the secret key’s length while preserving its uniformity and randomness. This paper proposes a key generation method based on time-varying and the reciprocity of wireless channels for Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) wireless communication systems. In the proposed technique, the complex impulse response (CIR) of the estimated channel state information (CSI) is extracted, and a quantization algorithm is designed to convert the maximum peaks of the CIR into secret key bits. The effectiveness of the proposed key generation technique is assessed in terms of the randomness of the produced key bits with different key lengths by using a statistical test suite of the National Institute of Standards and Technology (NIST). The proposed technique is employed in the MIMO-OFDM systems with different modulation schemes through Additive White Gaussian Noise (AWGN) and Rayleigh channels. The simulation results show that the secret keys with various key lengths generated from the proposed technique for the MIMO-OFDM systems guarantee randomness. Moreover, the proposed CSI-based key generation technique provides better effectiveness in terms of security when compared to some existing techniques.

Security Implementation on IoT using CoAP and Elliptical Curve Cryptography

IoT devices typically encompass objects or devices equipped with software and internet connectivity, allowing them to collect data. They have limited processing power, memory, and storage. These limitations can make it difficult to secure these devices, as traditional security measures may not be practical. Implementing security for IoT devices can be challenging due to these characteristics, but several steps can be taken to mitigate these challenges. Elliptic Curve Cryptography (ECC) can secure resource constrained IoT devices by providing a more efficient method of encryption and authentication than traditional methods such as RSA. In this paper, we analyzed the lightweight cryptographic algorithm ECC for securing resource-constrained devices such as IoT and evaluated its performance compared to the RSA cryptosystem. The analysis result indicates that ECC is considered to provide stronger security than RSA for the same key length. The CoAP protocol is applied to devices with limited resources, and an examination of its impact is conducted, considering three key performance metrics: CPU usage, bandwidth efficiency, and message communication latency.

EXPERIMENTAL STUDIES OF MULTICORE OPTICAL FIBER DURING TRANSMISSION CHARACTERISTICS OF CLASSICAL AND QUANTUM CHANNELS

Today, it is not possible to abandon modern sources of information; with such rapid development of technology, we need to analyze large amounts of data. To a greater extent, applications that require speed and volume of transported information are responsible for the increase in transmitted data, such as streaming and cloud data processing services, as well as traffic transfer between data centers. The experimental part of the research involves several schemes for distributing a quantum channel inside a multi-core fiber, as well as different models for placing classical channels. To transmit the quantum channel, scientific and educational complexes developed by the Qrate company were used; the transmission of the quantum channel was implemented based on the BB84 protocol. The article analyzes experimental studies on the parallel transmission of three quantum channels in a multi-core optical fiber with satisfaction of the quantum bit error rate and key length, as well as a study of the influence of classical power on the transmission of a quantum channel along the adjacent core of the fiber under study. Such research provides a new direction for the development of microstructured fibers specifically for the needs of quantum communications.

Uzamsal Alanda Bir Kripto-Stegano Hibrit Uygulama

The need for data security in communication is increasing with the developing
 technology. The best way to ensure data security is cryptography. Humanity has
 proposed many cryptography methods for hundreds of years. Today, there are
 complex cryptography algorithms, which are quite secure but require high processing
 power. Cryptography techniques used in the past are less secure but require less
 processing power. This article proposes an extended version of the Vigenère cipher,
 which is an ancient encryption method. Extended Vigenère cipher is able to encrypt
 upper and lower case letters, numeric characters, and punctuation marks. In addition,
 the method can use upper and lower case letters, numeric characters and punctuation
 marks as encryption key, and there is no key length limit. The cipher text generated
 with the extended Vigenère cipher is also hidden in an image to keep it safe in the
 transmission medium. Hiding is performed with LSB steganography, which is
 another data security method. Thus, both the readability and detectability of
 confidential data are reduced. The cryptological security of the proposed method is
 measured by the Avalanche effect. Steganographic safety is evaluated with SSIM
 and PSNR measurements. A user graphical interface has been developed and the
 maximum payload of the carrier image is measured before encryption. Proposed
 method applied on some test images with different specifications. 1 bit key
 modification avalanche effect results of proposed method with random plain texts
 between 1000-10000 characters with a key length of 8 and 16 characters is close to
 50%. Also, SSIM value calculated over 0.99 each time while maximum
 steganographic payload of the test images reached.

МЕТОД ОБЕСПЕЧЕНИЯ ЗАЩИТЫ ПЕРЕДАВАЕМЫХ СООБЩЕНИЙ В СИСТЕМЕ ADS-B С ИСПОЛЬЗОВАНИЕМ АППАРАТА КЛЕТОЧНЫХ АВТОМАТОВ

The purpose of the study is to develop a method for encoding of transmitted ADS-B messagesbetween aircraft. The open format 1090ES of transmitted data is critical in terms of carryingout various types of attacks that can lead to a violation of the safety of aircraft operations.The work is aimed at using means of encoding and decoding messages with a private key. Researchmethods are based on the application and development of streaming data encryption usingone-dimensional cellular automata. They operate as a generator of pseudo-random sequences thattransform the elementary states of a cell of a one-dimensional cellular automaton based on typicalhardware-oriented operations. The processes of encoding and decoding data fields are based onan analytical expression using typical logical operations (or, xor). This property allows parallelprocessing of message data fields. The result is the created method for ensuring the protection oftransmitted data, additionally encoding on transmission and decoding on message reception.A distinctive feature of the method is the preservation of the protocol forma. The method uses aone-dimensional cellular automaton that encodes and decodes the target fields (coordinates, heading,etc.) using a pseudo-random number generator. The developed method belongs to the class ofhardware-oriented methods. Critical for encoding and decoding properties of periodicity of datafields and key length are eliminated by choosing an initial irrational value and organizing the“streaming” work of the encoder. If the encoding automaton is running in streaming mode, thecurrent value depends on the history of some depth, determining the length of the "automatic key"from the ADS-B message will be algorithmically impossible due to data loss. The linear complexityof the method allows you to perform transformations at the data rate. Conclusion: the developmentof hardware-oriented methods of data encoding makes it possible to increase the efficiency ofusing the ADS-B system by counteracting various types of destructive actions.

Latency-Aware Accelerator of SIMECK Lightweight Block Cipher

This article presents a latency-optimized implementation of the SIMECK lightweight block cipher on a field-programmable-gate-array (FPGA) platform with a block and key lengths of 32 and 64 bits. The critical features of our architecture include parallelism, pipelining, and a dedicated controller. Parallelism splits the digits of the key and data blocks into smaller segments. Then, we use each segmented key and data block in parallel for encryption and decryption computations. Splitting key and data blocks helps reduce the required clock cycles. A two-stage pipelining is used to shorten the critical path and to improve the clock frequency. A dedicated controller is implemented to provide control functionalities. For the performance evaluation of our design, we report implementation results for two different cases on Xilinx 7-series FPGA devices. For our case one, the proposed architecture can operate on 382, 379, and 388 MHz frequencies for Kintex-7, Virtex-7, and Artix-7 devices. On the same Kintex-7, Virtex-7, and Artix-7 devices, the utilized Slices are 49, 51, and 50. For one encryption and decryption computation, our design takes 16 clock cycles. The minimum power consumption is 172 mW on the Kintex-7 device. For the second case, we targeted the same circuit frequency of 50 MHz for synthesis on Kintex-7, Virtex-7, and Artix-7 devices. With minimum hardware resource utilization (51 Slices), the least consumed power of 13.203 mW is obtained for the Kintex-7 device. For proof-of-concept, the proposed SIMECK design is validated on the NEXYS 4 FPGA with the Artix-7 device. Consequently, the implementation results reveal that the proposed architecture is suitable for many resource-constrained cryptographic applications.

An experimental study of FRP truss side plate joint

Ultra-high performance concrete (UHPC) slab - fiber reinforced polymer (FRP) truss hybrid beam has been proved as an effective and advanced bridge system. However, the limited shear strength and the significantly lower transverse properties compared with its longitudinal counterparts result in low rigidity and load carrying capacity of bolted FRP truss joints, which governs the overall performance of the UHPC slab- FRP truss hybrid beam. A FRP truss side plate joint was proposed which integrates a steel U-shaped gusset plate (SUGP) to reinforce the traditional bolted joint. The proposed joint outperformed the conventional bolted joints in terms of the failure mode, load carrying capacity, and stiffness. The load carrying capacity of the proposed joint can be improved by up to 63% and the ultimate deflection was reduced by up to 33%. The effects of a variety of key design parameters, including adhesive, bolt diameter, pre-torque, and length and thickness of the gusset plate, on the performance of the SUGP joint were evaluated. Test results showed that: (i) the adhesive between the pultruded FRP profiles and the steel gusset plate could increase both the initial stiffness and ultimate load carrying capacity of the steel SUGP joint; (ii) length and thickness of the steel gusset plate did not result in notable difference in the behavior of the steel SUGP joint for the range of parameters investigated herein; and (iii) application of pre-tightening torque within the thread of the bolts slightly improved the load carrying capacity but significantly improved the ductility of the steel SUGP joint.

An efficient, secure and verifiable conjunctive keyword search scheme based on rank metric codes over encrypted outsourced cloud data

Public key encryption with keyword search (PEKS) is a cryptographic primitive that allows a secure search for desired keywords of data users by a cloud server using a search token. To the best of our knowledge, we propose the first practical, semantic secure, and post-quantum PEKS scheme based on rank metric codes. The proposed scheme is secure against keyword guessing attack, reaction attack, and key exposure, and enjoys conjunctive keyword search, verifiability of search results using Bloom filter and garbled Bloom filter. We implement the scheme with C++ programming language on a desktop computer. At the security level of 256 bits, the scheme performs all the necessary steps for encryption, keyword search, and verification of search results for one keyword in 22.5 milliseconds. Furthermore, the public key length at this security level is about 5 kilobytes. We show that the scheme is more efficient than the existing relevant post-quantum ones.

The capillary length scale determines the influence of bubble-fin interactions and prediction of pool boiling from heat sinks

Heat sinks have the capability of increasing the operating heat flux limits of two-phase immersion cooling for passive electronics thermal management. For arrays of fins, investigation of the heat-flux-dependent variation of boiling regimes that can manifest along the fin height is required to predict performance and facilitate heat sink design. Existing methods for the prediction of fin boiling heat transfer which account for a variable heat transfer coefficient along the fin height assume single, isolated fins that behave like a boiling flat surface. When applied to fin arrays, thresholds for fin height and array spacing where this assumption holds true are not known. To establish when fins in an array can be described as isolated and follow flat surface boiling behavior, pool boiling experiments are performed using copper heat sinks in two fluids with vastly different properties: HFE-7100 and water. The spacing and height of the longitudinal fins are varied with respect to the capillary length scale, Lb, of both fluids, and high-speed visualizations enable the identification of different boiling regimes and bubble confinement between fins. Predictions based on the single, isolated fin assumption are compared to the experimental boiling curves. Heat transfer from heat sinks with both height and spacing above the capillary length scale is accurately predicted in both fluids. However, spacings smaller than Lb lead to bubble confinement, which causes the superheat at each heat flux to be lower than the predictions using the flat surface, particularly at low heat fluxes. Further, heights shorter than Lb are unable to support boiling along the fin sidewall once film boiling initiates at the base. This work firmly establishes the fluid capillary length as the key length scale at which these confinement and height effects need to be considered for accurate prediction and design of heat sinks for two-phase immersion cooling applications.

Modified ECC for Secure Data Transfer in Multi-Tenant Cloud Computing

Cloud computing technologies comprise various kinds of significant desirable constrains such as security, liability, government surveillance, telecommunications capacity, anonymity and privacy. The usage of cipher text technology is considered as a desired technique for performing the process of encryption in order to solve the issue of granting security to the data that are shared in the cloud. Similarly, the architecture of multi-tenant in the cloud computing system grants benefits to both the service providers and end-users which shares a common cloud platform to multiple tenants (i.e.) users and suitable resources are also computed by implementing proposed architecture. Therefore in this research work, the concept of cipher text multi-tenant are integrated for providing enhanced security to the data shared in the cloud environment. Hence a Modified Elliptic Curve Cryptography (MECC) based on Diffee Hellman algorithm is proposed in this research paper which provides enhanced security using alternate key generation. The encryption, decryption, upload and download time are calculated and it is concluded that the algorithm that is proposed in this research paper consumes less time for all these measures when comparing with other existing algorithms. Characteristics like less memory, high operational performance, small sized keys and rapid key generation process, and effective resource savings enable the modified ECC to obtain high efficiency. The encryption time of the proposed MECC system was 51ms with the key length 4096 bits, whereas existing method had 92ms as encryption time. Likewise With the key length of 4096 bits, the decryption time for the proposed model was 159ms. Accordingly the proposed system has reduced cipher text key size of 836KB when compared with the existing AES, Blow Fish, and Two Fish. Additionally, the key generation time (35 s) also seems to be considerably reduced when compared with the existing methods. These statements reveal that the proposed system outshine the state of art methods in terms of key generation time, encryption and decryption time and computational complexity.

Biometric-Based Key Generation and User Authentication Using Acoustic Characteristics of the Outer Ear and a Network of Correlation Neurons.

Trustworthy AI applications such as biometric authentication must be implemented in a secure manner so that a malefactor is not able to take advantage of the knowledge and use it to make decisions. The goal of the present work is to increase the reliability of biometric-based key generation, which is used for remote authentication with the protection of biometric templates. Ear canal echograms were used as biometric images. Multilayer convolutional neural networks that belong to the autoencoder type were used to extract features from the echograms. A new class of neurons (correlation neurons) that analyzes correlations between features instead of feature values is proposed. A neuro-extractor model was developed to associate a feature vector with a cryptographic key or user password. An open data set of ear canal echograms to test the performance of the proposed model was used. The following indicators were achieved: EER = 0.0238 (FRR = 0.093, FAR < 0.001), with a key length of 8192 bits. The proposed model is superior to known analogues in terms of key length and probability of erroneous decisions. The ear canal parameters are hidden from direct observation and photography. This fact creates additional difficulties for the synthesis of adversarial examples.

Effects of torsional control on the optical and electronic properties of monolayer NbS2: A first-principles study

Based on the first principle calculation, the torsional deformation control of single-layer graphene transition metal disulfide NbS 2 at different angles is systematically studied in this paper. The electronic properties include the energy gap change of the electronic band structure, the composition of the density of States, the trends of the real and imaginary parts of the dielectric function, and the electronic and optical properties such as absorption and reflection spectra. Our analysis shows that distortion can change the bond length of NbS 2 . Under torsion, the initial key length is 2.492 A, the shortest is 2.240 A, and the longest extended key is 2.744 A. On the other hand, the study of electronic and optical properties shows that the band structure of NbS 2 will have a split band gap at the Fermi level. When the torsion angle is 12 °, we notice that the electronic and optical properties of NbS 2 will change significantly, the energy band spacing will increase, and the corresponding minimum particle number will decrease significantly. The optical properties show that the torsion system can improve the storage capacity and polarizability of the material, improve the local optical response, and strongly impact the properties of the ultraviolet region. At the same time, it can improve the optical response to visible light and photocatalytic activity and effectively improve the transmittance of the material itself.

Powder spreading over realistic laser melted surfaces in metal additive manufacturing

Powder recoating is a key step in metal Additive Manufacturing (AM) processes where powder is spread across laser processed surfaces to add material for the next layer. Achieving the desired thin powder layers that are both sufficiently dense and uniform is essential for maintaining the requisite geometric tolerances and final part quality. In this study, we focus on the influence of the substrate surface topography by comparing spreading performance over a set of realistic surfaces. We simulate powder spreading over these surfaces using a calibrated non-spherical particle Discrete Element Model for Ti-6Al-4V that incorporates cohesion and Coulomb friction interactions between particles and surfaces. We identify the four key length scales of the recoating process determined by frictional contacts, powder size distribution, the layer thickness and the melted surface topography. We find that realistic AM surfaces show markedly different powder coverage compared to an idealised flat-plane. Rougher surfaces are found to be recoated with larger amounts of powder than smoother surfaces, as smaller particles get trapped by the grooves and valleys across the surface. Counterintuitively, we find that a finer more cohesive powder can achieve the best layer coverage over realistic surfaces - indicating that powder flowability is an incomplete measure of powder spreading performance on realistic AM surfaces. We also demonstrate how the recoating process can significantly size segregate the feedstock powder, favouring deposition of smaller sized particles on the melted surfaces.

A Modified Wei-Hua-He Digital Signature Scheme Based on Factoring and Discrete Logarithm

A symmetric cipher such as AES in cryptography is much faster than an asymmetric cipher but digital signatures often use asymmetric key ciphers because they provides the sender’s identity and data integrity. In this paper, a modified-He digital signature scheme is proposed using a one-way hash function. The proposed scheme, unlike the He signature technique, employs Euclid’s Division Lemma with large prime moduli p. Its security is built on large integer factoring, discrete logarithms and expanded root problems. The time complexity of the proposed scheme is O(log3p). The proposed modified-He scheme is efficient, as evidenced by the analytical results with key lengths greater than 512 bits.

New Constructions of Existential Unforgeable Aggregate Signature Scheme from CSP

In future, hundreds of years of mathematical problems that the security of public key cryptography algorithms rely on may be defeated by quantum algorithms. How can a digital signature scheme gracefully balance security and efficiency? This study uses the conjugate search problem and the left self-distributive system to combine and uses the RSA-like algorithm as the underlying structure to propose a new aggregated signature scheme. We, through the EUF game, under the random metaphor model, prove that the security of the scheme satisfies the adaptation unforgeability under selective message attack, the scheme can be finally reduced to the discrete logarithm problem or large prime number decomposition problem. In addition, we can achieve antiquantum attack and exhaustive attack by performing matrix calculations on the message, defining and changing the structure of the matrix by encoding, and setting thresholds for the matrix dimension and the length of the private key. In terms of efficiency, the message signature implementation is linear compared with the expansion rate in terms of storage and computing overhead, and the generation and verification of the final signature pair have nothing to do with the number of users. In addition, the length of the signature is fixed and the size is only the length of a single group, which effectively reduces the generation of public and private key pairs and saves a lot of storage space. The storage space and computational complexity are also effectively improved compared with other solutions.