Key Bits Research Articles

Cryptanalysis and Improvement to the Quantum Private Query Protocol for Enhancing Database Privacy

Abstract In order to protect the privacy of query user and database, some QKD-based quantum private query (QPQ) protocols were proposed. One example is the protocol proposed by Zhou et al., in which the user makes initial quantum states and derives the key bit by comparing the initial quantum state and the outcome state returned from the database by ctrl or shift mode instead of announcing
two non-orthogonal qubits as others which may leak part secret information. In some extent, the security of the database and the privacy of the user are strengthened. Unfortunately, we find that in this protocol, the dishonest user can obtain, utilizing unambiguous state discrimination, much more database information than that is analyzed in Zhou et al.’s original research. To strengthen the database security, we improved the mentioned protocol by modifying the information returned by the database in various ways. The analysis indicates that the security of the improved protocols is greatly enhanced.

Loss tolerance quantum key distribution based on the signal extraction model and advantage distillation technology.

Compared with traditional networks, quantum key distribution (QKD) offers the ultimate resources, allowing two remote users to share secret symmetric keys regardless of the capabilities of eavesdroppers. However, the widespread application of commercial QKD is still challenging due to the low photon detection efficiency and the extremely high transmission loss. Here we demonstrate a fully commercial phase-encoding QKD system using a signal extraction model and advantage distillation technology to suppress detector noise and perform real-time pre-error correction. 1.89 × 10-10 in the asymptotic case and 7.43 × 10-12 in the nonasymptotic case secret key bits per pulse are achieved with a total loss of 70.05 dB. This method not only increases the transmission loss tolerance but also provides a more realistic deployment of quantum communication.

Combined and General Methodologies of Key Space Partition for the Cryptanalysis of Block Ciphers

This paper proposes two new methods of key space partitioning for the cryptanalysis of block ciphers. The first one is called combined methodology of key space partition (CoMeKSPar), which allows us to simultaneously set some of the first and last consecutive bits of the key. In this way, the search is performed using the remaining middle bits. CoMeKSPar is a combination of two methods already proposed in the scientific literature, the Borges, Borges, Monier (BBM) and the Tito, Borges, Borges (TBB). The second method is called the general algorithm of key space reduction (GAKSRed), which makes it possible to perform a genetic algorithm search in the space formed by the unknown bits of the key, regardless of their distribution in the binary block. Furthermore, a method of attacking block ciphers is presented for the case where some key bits are known; the basic idea is to deduce some of the remaining bits of the block. An advantage of these methods is that they allow parallel computing, which allows simultaneous searches in different sub-blocks of key bits, thereby increasing the probability of success. The experiments are performed with the KLEIN (Small) lightweight block cipher using the genetic algorithm.

Free‐space quantum key distribution transmitter system using WDM filter for channel integration

AbstractIn this study, we report a transmitter system for free‐space quantum key distribution (QKD) using the BB84 protocol, which does not require an internal alignment process, by using a wavelength‐division multiplexing (WDM) filter and polarization‐encoding module. With a custom‐made WDM filter, the signals required for QKD can be integrated by simply connecting fibers, thus avoiding the laborious internal alignment required for free‐space QKD systems using conventional bulk‐optic setups. The WDM filter is designed to multiplex the single‐mode signals from 785‐nm quantum and 1550‐nm synchronization channels for spatial‐mode matching while maintaining the polarization relations. The measured insertion loss and isolation are 1.8 dB and 32.6 dB for 785 nm and 0.7 dB and 28.3 dB for 1550 nm, respectively. We also evaluate the QKD performance of the proposed system. The sifted key rate and quantum bit error rate are 1.6 Mbps and 0.62%, respectively, at an operating speed of 100 MHz, rendering our system comparable to conventional systems using bulk‐optic devices for channel integration.

A secure image steganography based on LSB technique and 2D chaotic maps

This paper introduces a pioneering, effective data-hiding algorithm using different sizes of cover images and different types of secret data (image, txt, and audio). The proposed algorithm is based on a hybrid 1D chaotic map combined with a 2D composite chaotic map paired with optimization and Least Significant Bits (LSB) techniques. We employ chaotic maps to create the initial embedding position vector, and LSB to hide the secret message in the cover image. The optimization technique utilizes the chaotic maps to optimize the random embedding sites, looking for value matches between the cover image pixels and the secret data bits. This partial improvement leads to a high-quality stego-image, a large embedding capacity, imperceptibility to the human eye, undetectability, and enhanced security. The outcomes of the extensive experiments show that when the payload is 4.2 bits per pixel, the peak signal-to-noise ratio value (PSNR), which expresses the visual quality, is above 30 dB. Furthermore, the experimental results illustrate that the system exhibits robustness against various types of attacks. As a final point of strength, the large key space (2^206) prevents the secret data from being resolved if stego-images are accessed by intruders or third parties. Even minor changes in key bits can significantly alter the extracted secret data, resulting in entirely different secret data.

Color Image Encryption Model Based on 3-D Chaotic Logistic Map and JAYA Algorithm

In this research, we have proposed a color image encryption model based on a three-dimensional chaotic logistic map and the JAYA algorithm. The 3-D chaotic logistic map generates three random keys for the color image. Further, the JAYA algorithm is utilized to find the parameter values of a 3-D chaotic logistic map based on the objective function. The JAYA algorithm is chosen because no parameter tuning is required and it has a better convergence rate to find the best solution over others. After generating the random key, exclusive-OR, and pixel-level bits are shuffled to get the final encrypted image. With the typical collection of color images, the simulation assessment was performed. The outcome indicates that the distorted image is entirely noisy. In comparison to best-practice approaches described in the literature, the suggested model outperforms them in terms of entropy while demonstrating poor PSNR and CC.

Cryptanalysis of Selected ARX-Based Block Ciphers

The security of digital communication and information systems is mostly dependent on block ciphers. ARX-based ciphers are widely used due to their simplicity and efficiency. This paper provides an exhaustive cryptanalysis of a subset of ARX-based block ciphers, with particular emphasis on SIMON, SPECK, and IDEA. These ciphers need to be exposed for their weaknesses in algebraic attack resistance and cryptographic properties such as key sensitivity. In addition, we assess the resource utilization and speed of these ciphers, both of which are critical for practical implementation. SMT (Satisfiability Modulo Theories) framework is utilized to tackle constraint fulfillment problems based on first-order logic. The following cryptographic steps use SMT solvers: differential cryptanalysis, collision attack, pre-image attack, modular root-finding, and cryptographic primitive verification. We show that SMT solvers can solve block cipher cryptanalysis constraints. In a cryptanalytic attack, we convert block cipher boolean equations to Z3py. The proposed cryptanalysis method evaluates ARX cipher performance. This method recovers the partial secret key using plaintext and ciphertext pairs, partial key bits, and a predetermined number of rounds. To determine whether SIMON, SPECK, or IDEA are appropriate for distinct security requirements, we conducted a comparative analysis of the results and presented them in tabulated form. This research builds a better understanding of ARX-based block ciphers and allows us to develop more robust and efficient cryptographic algorithms to protect sensitive data in modern communication systems.

Finite-Resource Performance of Small-Satellite-Based Quantum-Key-Distribution Missions

In satellite-based quantum-key-distribution (QKD), the number of secret bits that can be generated in a single satellite pass over the ground station is severely restricted by the pass duration and the free-space optical channel loss. High channel loss may decrease the signal-to-noise ratio due to background noise, reduce the number of generated raw key bits, and increase the quantum bit error rate (QBER), all of which have detrimental effects on the output secret key length. Under finite-size security analysis, a higher QBER increases the minimum raw key length necessary for nonzero secret-key-length extraction due to less efficient reconciliation and postprocessing overheads. We show that recent developments in finite-key analysis allow three different small-satellite-based QKD projects, CQT-Sat, the United Kingdom QUARC-ROKS, and QEYSSat, to produce secret keys even under conditions of very high loss, improving on estimates based on previous finite-key bounds. This suggests that satellites in low Earth orbit can satisfy finite-size security requirements but that this remains challenging for satellites further from Earth. We analyze the performance of each mission to provide an informed route toward improving the performance of small-satellite QKD missions. We highlight the short- and long-term perspectives on the challenges and potential future developments in small-satellite-based QKD and quantum networks. In particular, we discuss some of the experimental and theoretical bottlenecks and the improvements necessary to achieve QKD and wider quantum networking capabilities in daylight and at different altitudes. Published by the American Physical Society 2024

GMC-crypto: Low latency implementation of ECC point multiplication for generic Montgomery curves over GF(p)

Elliptic Curve Cryptography (ECC) is the front-runner among available public key cryptography (PKC) schemes due to its potential to offer higher security per key bit. All ECC-based cryptosystems heavily rely on point multiplication operation where its efficient realization has attained notable focus in the research community. Low latency implementation of the point multiplication operation is frequently required in high-speed applications such as online authentication and web server certification. This paper presents a low latency ECC point multiplication architecture for Montgomery curves over generic prime filed GF(p). The proposed architecture is able to operate for a general prime modulus without any constraints on its structure. It is based on a new novel pipelined modular multiplier developed using the Montgomery multiplication and the Karatsuba-Offman technique with a four-part splitting methodology. The Montgomery ladder approach is adopted on a system level, where a high-speed scheduling strategy to efficiently execute GF(p) operations is also presented. Due to these circuit and system-level optimizations, the proposed design delivers low-latency results without a significant increase in resource consumption. The proposed architecture is described in Verilog-HDL for 256-bit key lengths and implemented on Virtex-7 and Virtex-6 FPGA platforms using Xilinx ISE Design Suite. On the Virtex-7 FPGA platform, it performs a 256-bit point multiplication operation in just 110.9 us with a throughput of almost 9017 operations per second. The implementation results demonstrate that despite its generic nature, it produces low latency as compared to the state-of-the-art. Therefore, it has prominent prospects to be used in high-speed authentication and certification applications.

High-rate intercity quantum key distribution with a semiconductor single-photon source

Quantum key distribution (QKD) enables the transmission of information that is secure against general attacks by eavesdroppers. The use of on-demand quantum light sources in QKD protocols is expected to help improve security and maximum tolerable loss. Semiconductor quantum dots (QDs) are a promising building block for quantum communication applications because of the deterministic emission of single photons with high brightness and low multiphoton contribution. Here we report on the first intercity QKD experiment using a bright deterministic single photon source. A BB84 protocol based on polarisation encoding is realised using the high-rate single photons in the telecommunication C-band emitted from a semiconductor QD embedded in a circular Bragg grating structure. Utilising the 79 km long link with 25.49 dB loss (equivalent to 130 km for the direct-connected optical fibre) between the German cities of Hannover and Braunschweig, a record-high secret key bits per pulse of 4.8 × 10−5 with an average quantum bit error ratio of ~ 0.65% are demonstrated. An asymptotic maximum tolerable loss of 28.11 dB is found, corresponding to a length of 144 km of standard telecommunication fibre. Deterministic semiconductor sources therefore challenge state-of-the-art QKD protocols and have the potential to excel in measurement device independent protocols and quantum repeater applications.

Dynamic Cube Attacks against Grain-128AEAD

In this paper, we revisit the division property based dynamic cube attack on the full Grain-128 presented by Hao et al. at FSE 2020 and demonstrate that their attack on the full Grain-128 is invalid, that is, no key information could be successfully recovered. The theoretical framework for the dynamic cube attack provided by Hao et al. is correct, but the technique for building the MILP model in the dynamic cube attack has flaws. Besides, strong evidence indicates that their bias estimation method is not applicable to Grain-128AEAD and Grain-128. Accordingly, we introduce the three-subset division property without unknown subset (3SDP/u) into dynamic cube attacks and present a correct MILP modeling technique. In addition, we propose a heuristic technique called Polynomial Approximation with regard to Bias (PAB) to evaluate the bias in superpolies in the dynamic cube attack, which can provide a more accurate bias evaluation for high-dimension cubes. As a result, we implemented the dynamic cube attack based on 3SDP/u on 190-round Grain-128AEAD, and we could recover 3 key bits with a complexity 2103.44 and the success probability was evaluated to be 99.68%. For Grain-128, some zero-sum distinguishers of cube size 80 are given for the first time.

End‐to‐end demonstration for CubeSatellite quantum key distribution

AbstractQuantum key distribution (QKD) provides a method of ensuring security using the laws of physics, avoiding the risks inherent in cryptosystems protected by computational complexity. Here, the authors investigate the feasibility of satellite‐based quantum key exchange using low‐cost compact nano‐satellites. The first prototype of system level quantum key distribution aimed at the Cube satellite scenario is demonstrated. It consists of a transmitter payload, a ground receiver and simulated free space channel to verify the timing and synchronisation (T&S) scheme designed for QKD and the required high loss tolerance of both QKD and T&S channels. The transmitter is designed to be deployed on various up‐coming nano‐satellite missions in the UK and internationally. The effects of channel loss, background noise, gate width and mean photon number on the secure key rate (SKR) and quantum bit error rate (QBER) are discussed. The authors also analyse the source of QBER and establish the relationship between effective signal noise ratio (ESNR) and noise level, signal strength, gating window and other parameters as a reference for SKR optimisation. The experiment shows that it can tolerate the 40 dB loss expected in space to ground QKD and with small adjustment decoy states can be achieved. The discussion offers valuable insight not only for the design and optimisation of miniature low‐cost satellite‐based QKD systems but also any other short or long range free space QKD on the ground or in the air.

Encryption of Card Details Using AES with a 128-bit Key a Secure Approach to Data Protection

Data security is a critical concern in today's digital age, particularly regarding the protection of sensitive information such as cardholder data. This research paper explores the implementation of Advanced Encryption Standard (AES) encryption with a 128-bit key as a means of safeguarding card details. The project demonstrates the encryption and decryption process, ensuring data confidentiality and integrity. Utilizing the pycryptodome library in Python, the AES encryption technique is applied to encrypt card details, offering a secure approach to data protection. The methodology section outlines the AES encryption process, emphasizing key generation, encryption, and decryption. A detailed explanation of the Python implementation highlights the importance of key length and randomness in the encryption process. The results section presents the outcomes of encrypting and decrypting card details using AES encryption, analyzing the efficiency and security of the encryption process. Additionally, potential vulnerabilities and challenges encountered during implementation are discussed, along with their resolutions. In the discussion section, the research findings are interpreted in the context of data security and encryption standards. A comparison between AES encryption and other encryption algorithms is provided, evaluating performance and security aspects. Consideration is given to future research directions in the field of data encryption and security. Overall, this research paper underscores the significance of AES encryption with a 128-bit key for protecting cardholder information. By implementing AES encryption, organizations can enhance data security measures, ensuring the confidentiality and integrity of sensitive data in digital transactions. This abstract provides a concise overview of the research paper, summarizing the objectives, methodology, results, and implications of implementing AES encryption for card data protection. It highlights the importance of data security and encryption techniques in safeguarding sensitive information in digital transactions. Tokenizing cards enhances security, ensures regulatory compliance, boosts customer trust, and streamlines payment processes while reducing liability for organizations. Future developments may involve tokenizing cards even without customer consent. Keywords: Tokenization, Payment systems, Encryption, Fraud prevention

Gleeok: A Family of Low-Latency PRFs and its Applications to Authenticated Encryption

In this paper, we propose a new family of low-latency pseudorandom functions (PRFs), dubbed Gleeok.Gleeok utilizes three 128-bit branches to achieve a 256-bit key size while maintaining low latency. The first two branches are specifically designed to defend against statistical attacks, especially for differential attacks, while the third branch provides resilience against algebraic attacks. This unique design enables Gleeok to offer ultralow latency while supporting 256-bit keys, setting it apart from existing ciphers dedicated to low-latency requirements. In addition, we propose wide-block variants having three 256-bit branches. We also present an application of Gleeok to short-input authenticated encryption which is crucial for memory encryption and various realtime communication applications. Furthermore, we present comprehensive hardware implementation results that establish the capabilities of Gleeok and demonstrate its competitiveness against related schemes in the literature. In particular, Gleeok achieves a minimum latency of roughly 360 ps with the NanGate 15 nm cell library and is thus on par with related low-latency schemes that only feature 128-bit keys while maintaining minimal overhead when equipped in an authenticated mode of operation.

Square impossible differential attack and security of AES in known plaintext scenario

In this work, we examine the security of the 8-round AES, under the known plaintext attack scenario, a type of cryptographic attack in which an attacker has access to the plaintext and corresponding ciphertext pairs. We present an innovative impossible differential (ID) attack technique, which utilizes a specific ID characteristic, to perform the first known plaintext attack on the 8-round AES with a 256-bit key. Additionally, we propose a new attack methodology, known as the Square Impossible Differential (SID) attack, to enhance the effectiveness of the ID attacks on AES in chosen ciphertext or plaintext scenarios. The SID attack is a combination of a square attack and an ID attack. Our methodology introduces various new approaches, including the key indicator vectors, eliminating the key candidate through the Meet-in-The-Middle technique and mounting the guess and determine attack through the hash tables for the two-round decryption of one column of AES while determining the subkeys constituting the impossible differential characteristic for a given plaintext/ciphertext difference pair. Our approach demonstrates lower computational complexity compared to previous methods, and our analysis shows that the complexities of our known plaintext attack and SID attack are estimated to be 2220 and 2209, respectively.

Reference‐Frame‐Independent Mode‐Pairing Quantum Key Distribution with Advantage Distillation

AbstractThe coordination between distance and the secure key rate is one of the main challenges in the practical application of quantum key distribution (QKD). Mode‐pairing quantum key distribution is one of the schemes that can surpass the secret key capacity for repeaterless QKD. However, the protocol utilizes phase to encode the information, which leads to the problem of active stabilization in the interferometer. In this paper, a reference‐frame‐independent mode‐pairing quantum key distribution (RFI‐MP‐QKD) is proposed as an effective scheme to solve this problem. Moreover, the performance of the RFI‐MP‐QKD protocol is improved by applying the Advantage Distillation (AD) method in data post‐processing, which separates the highly correlated raw key bits from the weakly correlated information. The simulation results show that the secure key rate of RFI‐MP‐QKD has almost no degradation for reference frame deviation angles of . Compared to RFI‐MP‐QKD without AD method, the AD method decreases the quantum bit error rate from 0.04 to 0.012 and increases the maximum transmission distance from 406 to 450 km. The scheme proposed is expected to facilitate the practical implementation of RFI‐MP‐QKD, especially in cases of concerning reference frame alignment and high channel loss.

Lorenz Kaotik Devre Tabanlı Entropi Kaynağı ile Özgün Gerçek Rasgele Sayı Üretimi ve Ses Şifreleme Uygulaması

This paper introduces a methodology for generating secure cryptographic key bits from analog values obtained from the Lorenz chaotic circuit. The analog values are transferred from the chaotic circuit to the computer via an Analog Discovery-2 device and then post-processed by using a fixed-point number representation format and Von-Neumann corrector for the sampled values on the MATLAB program. By employing this method, the analog values are digitized and randomized as the main idea is to obtain secure and efficient statistically random bits. Furthermore, the generated random bits are utilized for secure audio transmission by demonstrating a practical application of the proposed methodology. In addition to the classical randomness test criteria, and NIST 800.22 statistical test suite, the throughput bit stream is also subjected to Chi-square and FIPS 140-1 tests to further evaluate its effectiveness. The results of these comprehensive tests confirm the successful performance of the proposed system in generating statistically random bits and its secure audio encryption system. The utilization of the Lorenz chaotic circuit as an entropy source in generating true random bits for secure audio transmission applications showcases the potential of the proposed system.

MILP-based differential cryptanalysis on full-round shadow

Shadow (Guo et al., 2021) is a lightweight block cipher based on a new logical combination method of AND-RX operation and the generalized Feistel structure with high diffusion and excellent performance in hardware implementation. In this paper, the components and structure of Shadow cipher are researched, and based on MILP automatic search algorithms for differential trails the 2-round iterative differential characteristics are obtained, then the full-round differential characteristics of both Shadow-32 and Shadow-64 are given. Moreover, targeting Shadow-32, we conduct 32-bit round-key recovery attack by using four 13.5-round differential trails, and the experimental verification shows that the time complexity is 226.02 and space complexity is 214.1. Recovering the 64 master key bits need to solve a system of multivariate equations over F2 with the time complexity more than 250.69. For Shadow-64, the process of recovering the master key is similar. Finally, we analyze the reasons for the insecurity of the Shadow cipher that may help to improve the cryptographic performance of the Shadow or provide help for a new block cipher design.

Designing hardware for a robust high-speed cryptographic key generator based on multiple chaotic systems and its FPGA implementation for real-time video encryption

Recent advancements in communication technologies have highlighted the pivotal role of information security for all individuals and entities. In response, researchers are increasingly focusing on cryptographic solutions to ensure the reliability of confidential information. Recognizing the superiority of chaotic systems preference as entropy source of cryptographic systems, this paper proposes a novel true random number generator (TRNG) design by combining four different chaotic systems outputs, tailored for real-time video encryption application. These chaotic systems are continuous-time Lorenz and fractional-order Chen-Lee systems, as well as discrete-time Logistic and Tent maps. This study generates true random bit (TRB) sequences at a high bit rate (25 Mbps) through the hardware implementations of four distinct chaotic systems to have the best statistical randomness in the resulting output. Then, the cryptographic true random key bits (8-bit at 25 MHz frequency) are employed in the post-processing with real-time video data by using the XOR operation, a fundamental post-processing algorithm. The real-time video encryption application is executed on an experimental assembly, composed of a Field Programmable Gate Array (FPGA) development kit, an OV7670 camera module, a VGA monitor, and prototype circuit boards for the chaotic systems. To evaluate the effectiveness of the proposed encryption system, several security assessments are conducted. These include NIST SP 800 − 22 statistical tests, FIPS 140-1 standards, chi-square tests, histogram and correlation analysis, and NPCR and UACI differential attack resilience tests. Consequently, the findings suggest that the presented real-time embedded cryptosystem is robust and suitable for secure communications, particularly in the realm of video transmission.

MieWC: Medical image encryption using wavelet transform and multiple chaotic maps

AbstractRecently, digital images have been widely used in several applications through advanced wearable devices and networks. Despite several benefits of digital images, such as easy distribution, storage, and reproduction, it is difficult to prevent the issue of identity theft, privacy leakage, and ownership conflicts. We present a wavelet‐based encryption technique, MieWC, to solve the above issues using multiple chaotic keys. This work uses multiple keys for the encryption process, which ensures high security and authenticity. Lorenz and logistic maps are used for chaotic key generation for diffusion and confusion processes. Further, the technique is tested for two different wavelet transforms, including integer wavelet transform (IWT) and discrete wavelet transform, with IWT giving better results. Hence, it is being used for further analysis. The proposed technique is easy to implement and provides high security with improved results. It has low time complexity and high key bit sensitivity. The result analysis further ensures resistance against crop attacks.