Random Strings Research Articles

EPAKA: An efficient and privacy-preserving authenticated key agreement scheme based on physical security for VANET

Vehicular ad hoc network (VANET) has been a promising technology in smart transportation system, which can enable information exchange between vehicles and roadside units (RSUs). However, the privacy of vehicles and RSUs is a critical challenge in VANET, as they may expose sensitive information to malicious attackers or unauthorized parties. Many existing authenticated key agreement (AKA) schemes aim to protect the privacy of vehicles and RSUs, but they often neglect the physical security of the devices involved in the communication. Therefore, we propose an efficient and privacy-preserving AKA scheme in VANET, which embeds physical unclonable function (PUF) and fuzzy extraction (FE) technology. PUF is a physical device that generates random strings based on their intrinsic characteristics and external inputs, which can protect the secrets in the devices from being stolen by attackers. FE can compensate for the drawbacks of PUF affected by environmental factors. Our scheme preserves the identity privacy of legitimate RSUs and vehicles, as well as intercepts and traces the identity of malicious attackers. In addition, we eliminate the involvement of the third party (TP) in the AKA phase to better meet the high-speed driving of vehicles. Finally, we conduct formal and informal security analyses in random oracle model (ROM), which prove that our scheme can resist various attacks. We also show in the performance analysis that our scheme has the lowest computational cost, communication overhead, and total energy consumption.

Quantum-Secured Data Centre Interconnect in a field environment

In the evolving landscape of quantum technology, the increasing prominence of quantum computing poses a significant threat to the security of conventional public key infrastructure. Quantum key distribution (QKD), an established quantum technology at a high readiness level, emerges as a viable solution with commercial adoption potential. QKD facilitates the establishment of secure symmetric random bit strings between two geographically separated, trustworthy entities, safeguarding communications from potential eavesdropping. In particular, data centre interconnects can leverage the potential of QKD devices to ensure the secure transmission of critical and sensitive information in preserving the confidentiality, security, and integrity of their stored data. In this article, we present the successful implementation of a QKD field trial within a commercial data centre environment that utilises the existing fibre network infrastructure. The achieved average secret key rate of 2.392 kbps and an average quantum bit error rate of less than 2% demonstrate the commercial feasibility of QKD in real-world scenarios. As a use case study, we demonstrate the secure transfer of files between two data centres through the Quantum-Secured Virtual Private Network, utilising secret keys generated by the QKD devices. %This demonstration marks a significant milestone in the deployment of QKD across Singapore, establishing a foundation for widespread adoption and enhancing the infrastructure for practical, quantum-safe communication in commercial environments.

PDQRRFF: Poisson-distributed quantum random reversible flip flop generator for BIST

Reversible logic has gained popularity recently because it allows circuits to use significantly less power. Due to the inherent reversibility of quantum operation, there is enormous interest in designing and optimizing reversible circuits. In this work, a new gate named as transvidkan gate, Quantum Random Reversible Flip Flop, Sequence generator, and Build in Self-Test (BIST) has been proposed. Quantum Random Reversible Flip Flop (QRRFF) is an emerging technology that is used in a variety of apps that use modern security and encryption systems. For creating a random string, typical approaches combine an entropy source with an elimination or bit-generation system. Quantum computing reversible logic chips and Low-power design are emerging as intriguing research topics. A classical logic-based 8-bit reversible comparator is represented using existing reversible gates. This study provides a BIST-based architecture for a comparator design that reduces the garbage outputs, quantum cost, and constant inputs. According to simulation result, the proposed approach outperforms traditional methods in terms of hardware complexity and quantum cost.

Implement quantum random number generation on the IBM quantum computer platform

Random numbers are a crucial component of any encryption activity in modern cryptography. Quantum Random Number Generators (QRNGs) produce truly random output strings to replace pseudo-random ones. The principle of QRNG relies on measuring qubit states, which excel in quantum computing applications, particularly on IBM's quantum computing platform. To construct a random number generator, the authors utilized IBM Q Experience's Qiskit quantum development toolkit. We developed QRNG applications on IBM quantum computers (7-qubit, 16-qubit, and 127-qubit) and tested the program's functionality on these quantum computing platforms. The quality assessment of the random strings was conducted according to NIST and AIS-31 standards. For NIST standards, to achieve good quality, the output string must reach a minimum of 1,593,088 bits to pass 16 tests per SP800-22 standard. According to AIS-31 standards, to achieve good quality, the output string must reach a minimum of 8,000,000 bits to pass 8 tests of the standard

Entropically secure encryption with faster key expansion

Entropically secure encryption is a way to encrypt a large plaintext with a small key and still have information-theoretic security, thus in a certain sense circumventing Shannon’s result that perfect encryption requires the key to be at least as long as the entropy of the plaintext. Entropically secure encryption is possible when a lower bound is known on the entropy of the plaintext from the adversary’s point of view. The typical implementation is to expand the short key to the size of the plaintext, e.g. by multiplication with a public random string, and then use one-time pad encryption. This works in the classical as well as the quantum setting. In this paper, we introduce a new key expansion method that is faster than existing ones. We prove that it achieves the same security. The speed gain is most notable when the key length is a sizeable fraction of the message length. In particular, a factor of 2 is gained in the case of approximate randomization of quantum states. In the classical case, we obtain a reduction of the ciphertext size.

Bayesian estimation of the Kullback-Leibler divergence for categorical systems using mixtures of Dirichlet priors.

In many applications in biology, engineering, and economics, identifying similarities and differences between distributions of data from complex processes requires comparing finite categorical samples of discrete counts. Statistical divergences quantify the difference between two distributions. However, their estimation is very difficult and empirical methods often fail, especially when the samples are small. We develop a Bayesian estimator of the Kullback-Leibler divergence between two probability distributions that makes use of a mixture of Dirichlet priors on the distributions being compared. We study the properties of the estimator on two examples: probabilities drawn from Dirichlet distributions and random strings of letters drawn from Markov chains. We extend the approach to the squared Hellinger divergence. Both estimators outperform other estimation techniques, with better results for data with a large number of categories and for higher values of divergences.

ESTIMAREA INTENSITĂȚII ALEATORII A FORȚELOR DE TRACȚIUNE ÎN SUPORTURILE ORGANELOR DE LUCRU ALE UNUI CULTIVATOR

The investigation on the unpredictability of the distribution of traction resistance forces on the working bodies of a specific type of MCLS complex cultivator is presented in the paper. The validation of the random character of the force that loads the active bodies is used to indicate the mathematical model that must be followed for the research of the soil processing system. Also, the research results elucidate some hypotheses issued in the conception and design of the machine: the more intense load for the working bodies from the lines of working bodies located immediately after the tractor, the existence of working bodies that are constantly more intensively requested and the causes. According to the literature, it is to be assumed that the forces that demand the working bodies, the supports, and the machine frame have a random nature. The conclusions of the descriptive, inferential statistical study (which do not quantify the random intensity) are explained together with the results. The experimental loads are compared to some of the most random strings to produce a quantitative estimate of the random intensity. As a result, processes that use random functions and the entirety of their approach are recommended in mathematical modelling for further research

Optimal Reference for DNA Synthesis

In recent years, DNA has emerged as a potentially viable storage technology. DNA synthesis, which refers to the task of writing the data into DNA, is perhaps the most costly part of existing storage systems. Consequently, the high cost and low throughput limit the practical use of available DNA synthesis technologies. It has been found that the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">homopolymer run</i> (i.e., the repetition of the same nucleotide) is a major factor affecting the synthesis and sequencing errors. Recently, [26] raised and studied the coding problem for efficient synthesis for DNA-based storage systems. Among other things, they studied the maximal code size under synthesis constraints. In [29], the authors studied the role of batch optimization in reducing the cost of large-scale DNA synthesis, for a given pool <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> of random quaternary strings of fixed length. This problem is related to the problem posed in [26] which can be viewed as the opposite side of the coin. Instead of seeking the largest code in which every codeword can be synthesized in a certain amount of time, they asked what is the average synthesis time of a randomly chosen string. Following the lead of [29], in this paper, we take a step forward towards the theoretical understanding of DNA synthesis, and study the homopolymer run of length <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> ≥ 1. Specifically, we are given a set of DNA strands <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> , randomly drawn from a Markovian distribution modeling a general homopolymer run length constraint, that we wish to synthesize. For this problem, we derive asymptotically tight high probability lower and upper bounds on the cost of DNA synthesis, for any <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> ≥ 1. Our bounds imply that, perhaps surprisingly, the periodic sequence ACGT is asymptotically optimal in the sense of achieving the smallest possible cost. Our main technical contribution is the representation of the DNA synthesis process as a certain constrained system, for which string techniques can be applied.

An Unbiased Quantum Random Number Generator Based on Boson Sampling

AbstractIt is proven that Boson sampling is a much promising model of optical quantum computation, which is applied to designing quantum computer successfully, such as “Jiuzhang”. However, the meaningful randomness of Boson sampling results has not been utilized or exploited. In this research, Boson sampling is applied to design a quantum random number generator (QRNG) by fully exploiting the randomness of Boson sampling results, and its prototype system is constructed with the programmable silicon photonic processor, which can generate unbiased random sequences and overcome the shortcomings of the existing discrete QRNGs such as source‐restricted, high demand for the photon number resolution capability of detector and slow self‐detection generator speed. Boson sampling is implemented as a random entropy source, and random bit strings with satisfactory randomness and uniformity can be obtained after post‐processing the sampling results. It is the first approach for applying the randomness of Boson sampling results to develop a practical prototype system for actual tasks, and the experiment results demonstrate that the designed Boson sampling‐based QRNG prototype system passes 15 tests of the NIST SP 800‐22 statistical test component, which proves that Boson sampling has great potential for practical applications with desirable performance besides quantum advantage.

Improved device-independent randomness expansion rates using two sided randomness

A device-independent randomness expansion (DIRE) protocol aims to take an initial random string and generate a longer one, where the security of the protocol does not rely on knowing the inner workings of the devices used to run it. In order to do so, the protocol tests that the devices violate a Bell inequality and one then needs to bound the amount of extractable randomness in terms of the observed violation. The entropy accumulation theorem lower bounds the extractable randomness of a protocol with many rounds in terms of the single-round von Neumann entropy of any strategy achieving the observed score. Tight bounds on the von Neumann entropy are known for the one-sided randomness (i.e. where the randomness from only one party is used) when using the Clauser–Horne–Shimony–Holt game. Here we investigate the possible improvement that could be gained using the two-sided randomness. We generate upper bounds on this randomness by attempting to find the optimal eavesdropping strategy, providing analytic formulae in two cases. We additionally compute lower bounds that outperform previous ones and can be made arbitrarily tight (at the expense of more computation time). These bounds get close to our upper bounds, and hence we conjecture that our upper bounds are tight. We also consider a modified protocol in which the input randomness is recycled. This modified protocol shows the possibility of rate gains of several orders of magnitude based on recent experimental parameters, making DIRE significantly more practical. It also enables the locality loophole to be closed while expanding randomness in a way that typical spot-checking protocols do not.

Round efficient privacy-preserving federated learning based on MKFHE

Federated learning (FL) was created with the intention of enabling collaborative training of models without the need for direct data exchange. However, data leakage remains an issue in FL. Multi-Key Fully Homomorphic Encryption (MKFHE) is a promising technique that allows computations on ciphertexts encrypted by different parties. MKFHE’s aptitude to handle multi-party data makes it an ideal tool for implementing privacy-preserving federated learning.We present a multi-hop MKFHE with compact ciphertext. MKFHE allows computations on data encrypted by different parties. In MKFHE, the compact ciphertext means that the size of the ciphertext is independent of the number of parties. The multi-hop property means that parties can dynamically join the homomorphic computation at any time. Prior MKFHE schemes were limited by their inability to combine these desirable properties. To address this limitation, we propose a multi-hop MKFHE scheme with compact ciphertext based on the random sample common reference string(CRS). We construct our scheme based on the residue number system (RNS) variant CKKS17 scheme, which enables efficient homomorphic computation over complex numbers due to the RNS representations of numbers.We construct a round efficient privacy-preserving federated learning based on our multi-hop MKFHE. In FL, there is always the possibility that some clients may drop out during the computation. Previous HE-based FL methods did not address this issue. However, our approach takes advantage of multi-hop MKFHE that users can join dynamically and constructs an efficient federated learning scheme that reduces interactions between parties. Compared to other HE-based methods, our approach reduces the number of interactions during a round from 3 to 2. Furthermore, in situations where some users fail, we are able to reduce the number of interactions from 3 to just 1.

Visual word processing efficiency for Chinese characters and English words

The Word Superiority Effect (WSE) refers to the phenomenon where a single letter is recognized more accurately when presented within a word, compared to when it is presented alone or in a random string. However, previous research has produced conflicting findings regarding whether this effect also occurs in the processing of Chinese characters. The current study employed the capacity coefficient, a measure derived from the Systems Factorial Technology framework, to investigate processing efficiency and test for the superiority effect in Chinese characters and English words. We hypothesized that WSE would result in more efficient processing of characters/words compared to their individual components, as reflected by super capacity processing. However, contrary to our predictions, results from both the “same” (Experiment 1) and “different” (Experiment 2) judgment tasks revealed that native Chinese speakers exhibited limited processing capacity (inefficiency) for both English words and Chinese characters. In addition, results supported an English WSE with participants integrating English words and pseudowords more efficiently than nonwords, and decomposing nonwords more efficiently than words and pseudowords. In contrast, no superiority effect was observed for Chinese characters. To conclude, the current work suggests that the superiority effect only applies to English processing efficiency with specific context rules and does not extend to Chinese characters.

A binary embedding of the stable line-breaking construction

We embed Duquesne and Le Gall’s stable tree into a binary compact continuum random tree (CRT) in a way that solves an open problem posed by Goldschmidt and Haas. This CRT can be obtained by applying a recursive construction method of compact CRTs as presented in earlier work to a specific distribution of a random string of beads, i.e. a random interval equipped with a random discrete measure. We also express this CRT as a tree built by replacing all branch points of a stable tree by i.i.d. copies of a Ford CRT, each rescaled by a factor intrinsic to the stable CRT.

A new lattice-based online/offline signatures framework for low-power devices

Lattice-based online/offline signature scheme enjoys the advantage of resisting quantum feature besides the short online response time. The existing Fiat-Shamir with aborts paradigm candidates do not have perfect online/offline property, and the hash-sign-switch ones usually increase the signature sizes. In this paper we mainly address its online time and the length of signature issues, and propose a new and efficient paradigm of its construction for lattice assumptions over rings. In this paradigm the signer tries to sign for a random string and the message respectively. Specifically, we first discuss the generic construction of Fiat-Shamir lattice-based signatures. Then for a large class of lattice-based relations over rings, we propose an improved framework designed for low-power devices. This new framework allows the signer to extract a part of the signature only for a random string chosen in offline time, and thus can obtain the whole signature by less online time. In addition, the resulting scheme slightly reduces the signature size compared to the Fiat-Shamir counterparts. The performance analysis shows that our construction is efficient.

Asymptotic normality for -dependent and constrained -statistics, with applications to pattern matching in random strings and permutations

AbstractWe study (asymmetric) $U$ -statistics based on a stationary sequence of $m$ -dependent variables; moreover, we consider constrained $U$ -statistics, where the defining multiple sum only includes terms satisfying some restrictions on the gaps between indices. Results include a law of large numbers and a central limit theorem, together with results on rate of convergence, moment convergence, functional convergence, and a renewal theory version.Special attention is paid to degenerate cases where, after the standard normalization, the asymptotic variance vanishes; in these cases non-normal limits occur after a different normalization.The results are motivated by applications to pattern matching in random strings and permutations. We obtain both new results and new proofs of old results.

An Efficient Threshold Access-Structure for RLWE-Based Multiparty Homomorphic Encryption

We propose and implement a multiparty homomorphic encryption (MHE) scheme with a t-out-of-N-threshold access-structure that is efficient and does not require a trusted dealer in the common random string model. We construct this scheme from the ring-learning-with-error assumptions and as an extension of the MHE scheme of Mouchet et al. (PETS 21). By means of a specially adapted share re-sharing procedure, this extension can be used to relax the N-out-of-N-threshold access-structure of the original scheme into a t-out-of-N-threshold one. This procedure introduces only a single round of communication during the setup phase, after which any set of at least t parties can compute a t-out-of-t additive sharing of the secret-key with no interaction; this new sharing can be used directly in the scheme of Mouchet et al. We show that, by performing Shamir re-sharing over the MHE ciphertext-space ring with a carefully chosen exceptional set, this reconstruction procedure can be made secure and has negligible overhead. Moreover, it only requires the parties to store a constant-size state after its setup phase. Hence, in addition to fault tolerance, lowering the corruption threshold also yields considerable efficiency benefits, by enabling the distribution of batched secret-key operations among the online parties. We implemented and open-sourced our scheme in the Lattigo library.

Exploring the carry-over of top-down attentional settings in dynamic conditions.

A top-down attentional set can persist from a relevant task to an irrelevant task, influencing allocation of attentional resources, visual search, and performance. While this "carry-over" effect has been found across numerous experiments, past studies have utilised paradigms that present similar tasks to the same spatial location. The present research explored whether attentional settings persist in more dynamic situations. In Experiment 1, participants played a computer game that encouraged a horizontal, vertical, or random spread of search. After 10 or 30 s, they moved 90° to their right and monitored a driving video for hazards. Eye movements to the videos were not affected by the characteristics of the preceding game, revealing no carry-over of attentional settings. One possible explanation for this was the visuospatial shift between the tasks. To explore this further, Experiment 2 adopted a similar paradigm to previous research; participants searched horizontal, vertical, or random letter strings before completing an image search. In one block the tasks were presented to the same screen, and in one block the tasks were presented to different screens (incorporating a 90° visuospatial shift mid-trial). Carry-over was found in the one-screen block, with a significantly wider horizontal search and a narrower vertical search in the pictures after a horizontal letter search. However, there was no carry-over from the letter to the picture task in the two-screen block. This indicates the flexibility of attentional control in dynamic situations, and it is suggested that persistence of attentional settings will be most costly under stable conditions.

Private Randomness Agreement and its Application in Quantum Key Distribution Networks

We define a variation on the well-known problem of private message transmission. This new problem called <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">private randomness agreement</i> (PRA) gives two participants access to a public, authenticated channel alongside the main channels, and the ‘message’ is not fixed a priori. Instead, the participants’ aim to agree on a random string completely unknown to a computationally unbounded adversary. We define privacy and reliability, and show that PRA cannot be solved in a single round. We then show that it can be solved in three rounds, albeit with exponential cost, and give an efficient four-round protocol based on polynomial evaluation.

Robust and Reusable Fuzzy Extractors from Non-Uniform Learning with燛rrors Problem

A fuzzy extractor can extract an almost uniform random string from a noisy source with enough entropy such as biometric data. To reproduce an identical key from repeated readings of biometric data, the fuzzy extractor generates a helper data and a random string from biometric data and uses the helper data to reproduce the random string from the second reading. In 2013, Fuller et al. proposed a computational fuzzy extractor based on the learning with errors problem. Their construction, however, can tolerate a sub-linear fraction of errors and has an inefficient decoding algorithm, which causes the reproducing time to increase significantly. In 2016, Canetti et al. proposed a fuzzy extractor with inputs from low-entropy distributions based on a strong primitive, which is called digital locker. However, their construction necessitates an excessive amount of storage space for the helper data, which is stored in authentication server. Based on these observations, we propose a new efficient computational fuzzy extractor with small size of helper data. Our scheme supports reusability and robustness, which are security notions that must be satisfied in order to use a fuzzy extractor as a secure authentication method in real life. Also, it conceals no information about the biometric data and thanks to the new decoding algorithm can tolerate linear errors. Based on the non-uniform learning with errors problem, we present a formal security proof for the proposed fuzzy extractor. Furthermore, we analyze the performance of our fuzzy extractor scheme and provide parameter sets that meet the security requirements. As a result of our implementation and analysis, we show that our scheme outperforms previous fuzzy extractor schemes in terms of the efficiency of the generation and reproduction algorithms, as well as the size of helper data.

Improving image deblurring

In this paper, we present a new model to improve image deblurring for the Helsinki Deblur Challenge, promoted by the Finnish Inverse Problems Society in the year of 2021. The challenge consisted in deblurring photographs of random strings of text with varying levels of blur caused by misfocusing the camera. This problem is usually referred to in the literature as out-of-focus deblur. A set of blurred and sharp images was available and also images of dots and other technical targets (horizontal and vertical lines) with the same camera settings. From the observation that the convolution of the sharp images with a uniform disk, which is commonly used as the point spread function (PSF) for the out-of-focus deblur problem, resulted in a image different from the observed blurred images, we observed a pattern that could be modeled as a contrast map. By multiplying this map to the observed images it was possible to significantly improve the image deblurring algorithms, specially for high levels of blur. This map was obtained from the blurred and sharp images that were available. Also, we propose a new deblurring function to be used with the fixed point Regularization by Denoise (RED) algorithm and the results were compared with the Least Absolute Shrinkage and Selection Operator (LASSO) algorithm.