Search Results (1,572)

Blind signatures are one of the key techniques of Privacy-Enhancing Technologies (PETs). They appear as a component of many schemes, including, in particular, the Privacy Pass technology. Blind-signature schemes provide provable privacy: the signer cannot derive any information about a message signed at user’s request. Unfortunately, in practice, this might be just an illusion. We consider a novel but realistic threat model where the user does not participate in the protocol directly but instead uses a provided black-box device. We then show that the black-box device may be implemented in such a way that, despite a provably secure unblinding procedure, a malicious signer can link the signing protocol transcript with a resulting unblinded signature. Additionally, we show how to transmit any short covert message between the black-box device and the signer. We prove the stealthiness of these attacks in anamorphic cryptography model, where the attack cannot be detected even if all private keys are given to an auditor. At the same time, an auditor will not detect any irregular behavior even if the secret keys of the signer and the device are revealed for audit purposes (anamorphic cryptography model). We analyze the following schemes: (1) Schnorr blind signatures, (2) Tessaro–Zhu blind signatures, and their extensions. We provide a watchdog countermeasure and conclude that similar solutions are necessary in practical implementations to defer most of the threats. Full article

A semigroup S is termed a generalized Clifford semigroup (GC-semigroup) if it forms a strong semilattice of π-groups. This paper explores necessary and sufficient conditions for a GC-monoid to be nearly complete within certain subclasses. These subclasses are distinguished by the nature of their linking homomorphisms, which may be bijective, surjective, injective, or image trivial. The findings provide a deeper understanding of the structural integrity and completeness of GC-monoids, contributing valuable insights to the theoretical framework of semigroup theory. Applications of this study span various fields, including cryptography for secure algorithm design, coding theory and quantum computing for advanced quantum algorithms. The established criteria also support further research in mathematical biology and automorphic theory, demonstrating the broad relevance and utility of nearly complete GC-monoids. Full article

With the advent of cloud computing and the era of big data, there is an increasing focus on privacy computing. Consequently, homomorphic encryption, being a primary technique for achieving privacy computing, is held in high regard. Nevertheless, the efficiency of homomorphic encryption schemes is significantly impacted by bootstrapping. Enhancing the efficiency of bootstrapping necessitates a dual focus: reducing the computational burden of outer product operations integral to the process while rigorously constraining the noise generated by bootstrapping within predefined threshold limits. The FINAL scheme is a fully homomorphic encryption scheme based on the number theory research unit (NTRU) and learning with errors (LWE) assumptions. The performance of the FINAL scheme is better than that of the TFHE scheme, with faster bootstrapping and smaller bootstrapping and key-switching keys. In this paper, we introduce ellipsoidal Gaussian sampling to generate keys f and g in the bootstrapping of the FINAL scheme, so that the standard deviations of keys f and g are different and reduce the bootstrapping noise by 76%. However, when q is fixed, the boundary for bootstrapping noise remains constant. As a result, larger decomposition bases are used in bootstrapping to reduce the total number of polynomial multiplications by 47%, thus improving the efficiency of the FINAL scheme. The optimization scheme outperforms the original FINAL scheme with 33.3% faster bootstrapping, and the memory overhead of blind rotation keys is optimized by 47%. Full article

In this study, we present the Response-Based Key Encapsulation Mechanism (R-KEM), an ephemeral key encapsulation and recovery scheme tailored for cryptographic systems in high-noise, high-jamming network environments. By adopting the Challenge–Response Pair (CRP) mechanism for both key encapsulation and authentication, R-KEM eliminates the need to store secret keys on the device, favoring on-demand key generation. By maintaining only encrypted data on the device, R-KEM significantly enhances security, ensuring that in the event of an attack, no sensitive information can be compromised. Its novel error-correcting strategy efficiently corrects 20 to 23 bits of errors promptly, eliminating the need for redundant helper data and fuzzy extractors. R-KEM is ideally suited for terminal devices with constrained computational resources. Our comprehensive performance analysis underscores R-KEM’s ability to recover error-free cryptographic keys in noisy networks, offering a superior alternative to conventional methods that struggle to maintain secure data transmission under such challenges. This work not only demonstrates R-KEM’s efficacy but also paves the way for more resilient cryptographic systems in noise-prone environments. Full article

This paper introduces two information-theoretically quantum secure direct communication protocols that accomplish information exchange between Alice and Bob in the first case, and among Alice, Bob, and Charlie in the second case. Both protocols use a novel method, different from existing similar protocols, to embed the secret information in the entangled compound system. This new way of encoding the secret information is one of the main novelties of this paper, and a distinguishing feature compared to previous works in this field. A second critical advantage of our method is its scalability and extensibility because it can be seamlessly generalized to a setting involving three, or more, players, as demonstrated by the second protocol. This trait is extremely beneficial in many real-life situations, where many spatially separated players posses only part the secret information that must be transmitted to Alice, so that she may obtain the complete secret. Using the three-player protocol, this task can be achieved in one go, without the need to apply a typical QSDC protocol twice, where Alice first receives Bob’s and then Charlie’s information. The proposed protocol does not require pre-shared keys or quantum signatures, making it less complicated and more straightforward. Finally, in anticipation of the coming era of distributed quantum computing, our protocols offer the important practical advantage of straightforward implementation on contemporary quantum computers, as they only require standard CNOT and Hadamard gates. Full article

The incorporation of Internet of Things (IoT) edge nodes into assistive technologies greatly improves the daily lives of individuals with disabilities by facilitating real-time data processing and seamless connectivity. However, the increasing adoption of IoT edge devices intended for individuals with disabilities presents significant security challenges, particularly concerning the safeguarding of sensitive data and the heightened risk of cyber vulnerabilities. To effectively mitigate these risks, advanced cryptographic protocols, including those based on elliptic curve cryptography, have been proposed to establish robust security measures. While these protocols are effective in reducing the risk of data exposure, they often demand considerable computational resources, which poses challenges for cost-effective IoT devices. Therefore, it is essential to prioritize the effective execution of cryptographic algorithms, as they rely on finite field operations such as multiplication, inversion, and division. Among these computations, field multiplication is particularly critical, serving as the backbone for the other operations. This study intends to create an innovative hybrid systolic array design for the Dickson basis multiplier, which integrates both serial and parallel inputs to enhance overall performance. The proposed design is anticipated to significantly reduce space and power consumption, thereby enabling the secure execution of complex cryptographic algorithms on resource-limited IoT devices designed for disabled people. By addressing these pressing security issues, the study aspires to fully leverage IoT technologies to enhance the living standards of individuals with disabilities, while ensuring that their privacy and security are meticulously maintained. Full article

Immersive environments have brought a great transformation in human–computer interaction by enabling realistic and interactive experiences within simulated or augmented spaces. In these immersive environments, virtual assets such as custom avatars, digital artwork, and virtual real estate play an important role, often holding a substantial value in both virtual and real worlds. However, this value also makes them attractive to fraudulent activities. As a result, ensuring the authenticity and integrity of virtual assets is of concern. This study proposes a cryptographic solution that leverages digital signatures and hash algorithms to secure virtual assets in immersive environments. The system employs RSA-2048 for signing and SHA-256 hashing for binding the digital signature to the asset’s data to prevent tampering and forgery. Our experimental evaluation demonstrates that the signing process operates with remarkable efficiency; over ten trials, the signing time averaged 17.3 ms, with a narrow range of 16–19 ms and a standard deviation of 1.1 ms. Verification times were near-instantaneous (0–1 ms), ensuring real-time responsiveness. Moreover, the signing process incurred a minimal memory footprint of approximately 4 KB, highlighting the system’s suitability for resource-constrained VR applications. Simulations of tampering and forgery attacks further validated the system’s capability to detect unauthorized modifications, with a 100% detection rate observed across multiple trials. While the system currently employs RSA, which may be vulnerable to quantum computing in the future, its modular design ensures crypto-agility, allowing for the integration of quantum-resistant algorithms as needed. This work not only addresses immediate security challenges in immersive environments but also lays the groundwork for broader applications, including regulatory compliance for financial virtual assets. Full article

The article proposes a cryptographic system with absolute security features for use in authenticating access to resources in smart grid systems, taking into account prosumer solutions to ensure a high level of security of transactions on the energy market that meet the requirements established in the Directive of the European Parliament of 14 December 2022 no. 2555 NIS2, requiring “dynamic authentication” prior to the release of transaction data for key services, covers energy market operators as a key service and is particularly important for ensuring security. The article presents an innovative cryptographic system that, according to the authors’ knowledge, is the only one in the world that meets the NIS2 requirements in the field of “dynamic authentication” and the Quantum-Resistant requirements intended for distributed systems and smart grids. The proposed solution eliminates vulnerabilities related to digital identity theft and its reuse, i.e., practically eliminates the possibility of impersonation. Full article

Quantum cryptography continues to be an area of significant research and educational interest. Here, a straightforward and reliable approach to both the experimental and theoretical aspects of quantum key distribution is presented, tailored for senior undergraduate students. Focusing on illustrating the essential concepts of the B92 protocol through a combination of optical experiments and custom-developed computational tools, this work offers a thorough exploration of quantum cryptography according to the principles of the B92 protocol. Full article

Steganography serves a crucial role in secure communications by concealing information within non-suspicious media, yet traditional methods often lack resilience and efficiency. Distributed steganography, which involves fragmenting messages across multiple containers using secret sharing schemes, offers improved security but increases complexity. This paper introduces a novel two-phase embedding algorithm that mitigates these issues, enhancing both security and practicality. Initially, the secret message is divided into shares using Shamir’s Secret Sharing and embedded into distinct media containers via pseudo-random LSB paths determined by a unique internal stego key. Subsequently, this internal key is further divided and embedded using a shared stego key known only to the sender and receiver, adding an additional security layer. The algorithm effectively reduces key management complexity while enhancing resilience against sophisticated steganalytic attacks. Evaluation metrics, including Peak Signal-to-Noise Ratio (PSNR) and Structural Similarity Index Measure (SSIM), demonstrate that stego images maintain high quality even when embedding up to 0.95 bits per pixel (bpp). Additionally, robustness tests with StegoExpose and Aletheia confirm the algorithm’s stealthiness, as no detections are made by these advanced steganalysis tools. This research offers a secure and efficient advancement in distributed steganography, facilitating resilient information concealment in sophisticated communication environments. Full article

Randomness plays a crucial role in numerous applications, with cryptography being one of the most significant areas where its importance is evident. A major challenge in cryptographic applications is designing a reliable key generator that meets stringent security requirements. Existing methods often suffer from predictability and fail to provide robust randomness, necessitating novel mathematical approaches. In this study, we propose an innovative mathematical framework that integrates quantum wave functions with chaotic systems to enhance the unpredictability and security of random number generation. The proposed approach leverages the inherent uncertainty of quantum mechanics and the dynamic behavior of chaos to generate statistically strong random sequences. The analysis results confirm that the proposed generator successfully passes all standard statistical randomness tests, demonstrating its effectiveness in cryptographic applications. Additionally, we present a practical implementation of the proposed method as an image encryption algorithm, showcasing its potential for real-world information security solutions. The findings suggest that this approach can contribute significantly to secure communication systems, financial transactions, and other domains requiring high-level cryptographic security. Full article

The emergence of the Internet of Things (IoT) technologies has greatly enhanced the lives of individuals with disabilities by leveraging radio frequency identification (RFID) systems to improve autonomy and access to essential services. However, these advancements also pose significant security risks, particularly through side-channel attacks that exploit weaknesses in the design and operation of RFID tags and readers, potentially jeopardizing sensitive information. To combat these threats, several solutions have been proposed, including advanced cryptographic protocols built on cryptographic algorithms such as elliptic curve cryptography. While these protocols offer strong protection and help minimize data leakage, they often require substantial computational resources, making them impractical for low-cost RFID tags. Therefore, it is essential to focus on the efficient implementation of cryptographic algorithms, which are fundamental to most encryption systems. Cryptographic algorithms primarily depend on various finite field operations, including field multiplication, field inversion, and field division. Among these operations, field multiplication is especially crucial, as it forms the foundation for executing other field operations, making it vital for the overall performance and security of the cryptographic framework. The method of implementing field multiplication operation significantly influences the system’s resilience against side-channel attacks; for instance, implementation using unidirectional systolic array structures can provide enhanced error detection capabilities, improving resistance to side-channel attacks compared to traditional bidirectional multipliers. Therefore, this research aims to develop a novel unidirectional systolic array structure for the Dickson basis multiplier, which is anticipated to achieve lower space and power consumption, facilitating the efficient and secure implementation of computationally intensive cryptographic algorithms in RFID systems with limited resources. This advancement is crucial as RFID technology becomes increasingly integrated into various IoT applications for individuals with disabilities, including secure identification and access control. Full article

The Internet of Things is used in many application areas in our daily lives. Ensuring the security of valuable data transmitted over the Internet is a crucial challenge. Hash functions are used in cryptographic applications such as integrity, authentication and digital signatures. Existing lightweight hash functions leverage task parallelism but provide limited scalability. There is a need for lightweight algorithms that can efficiently utilize multi-core platforms or distributed computing environments with high degrees of parallelization. For this purpose, a data-parallel approach is applied to a lightweight hash function to achieve massively parallel software. A novel structure suitable for data-parallel architectures, inspired by basic tree construction, is designed. Furthermore, the proposed hash function is based on a lightweight block cipher and seamlessly integrated into the designed framework. The proposed hash function satisfies security requirements, exhibits high efficiency and achieves significant parallelism. Experimental results indicate that the proposed hash function performs comparably to the BLAKE implementation, with slightly slower execution for large message sizes but marginally better performance for smaller ones. Notably, it surpasses all other evaluated algorithms by at least 20%, maintaining a consistent 20% advantage over Grostl across all data sizes. Regarding parallelism, the proposed PLWHF achieves a speedup of approximately 40% when scaling from one to two threads and 55% when increasing to three threads. Raspberry Pi 4-based tests for IoT applications have also been conducted, demonstrating the hash function’s effectiveness in memory-constrained IoT environments. Statistical tests demonstrate a precision of ±0.004, validate the hypothesis in distribution tests and indicate a deviation of ±0.05 in collision tests, confirming the robustness of the proposed design. Full article

With the rapid development of quantum computers and quantum computing, Internet of Things (IoT) networks equipped with traditional cryptographic algorithms have become very weak against quantum attacks. This paper focuses on the privacy-preserving problem in IoT networks and proposes a certificateless ring signature (CLRS) scheme. This CLRS is constructed with lattice theories, which show promising advantages in resisting quantum attacks. Meanwhile, the certificateless mechanism reduces the key control ability of the key generation center (KGC) by adding personal secret keys to the private key generated by the system. Meanwhile, the ring signature mechanism protects users’ privacy information through a non-central control mechanism. Next, the security proof in a random oracle model is given, which shows that this CLRS scheme can obtain unforgeability and ensure the signer’s anonymity. Its security properties include non-repudiation, traceability, and post-quantum security. Then, the efficiency comparison and performance results show that this CLRS scheme is more efficient and practical than similar schemes. Moreover, this work presents an exploration of the post-quantum cryptographic algorithm and its application in IoT networks. Full article

The development of quantum computers presents a great challenge for current cryptographic algorithms. Post-quantum cryptography has been proposed to secure against quantum computers in the near future. Modular polynomial multiplication is a frequent arithmetic operation in post-quantum cryptography. In this paper, a low-cost and efficient pipelined architecture for modular polynomial multiplication in Saber has been proposed and synthesized with the Virtex UltraScale + xcu200-fsgd2104-2-e board. It can achieve a frequency of 250 MHz and only uses 11,499 LUTs, 7034 FFs and 32 IOs. Full article