Encryption Scheme Research Articles

An efficient and compromise-resilient image encryption scheme for resource-constrained environments.

The secret keys produced by current image cryptosystems, which rely on chaotic sequences, exhibit a direct correlation with the size of the image. As the image dimensions expand, the generation of extensive chaotic sequences in the encryption and decryption procedures becomes more computationally intensive. Secondly, a common problem in existing image encryption schemes is the compromise between privacy and efficiency. Some existing lightweight schemes reveal patterns in encrypted images, while others impose heavy computational burdens during encryption/decryption due to the need for large chaotic sequences. In this study, we introduce a lightweight image encryption scheme that involves partitioning the image into uniformly sized tiles and generating a chaotic sequence accordingly. This approach diminishes the necessity to create extensive chaotic sequences equal to the tile size, which is significantly smaller than the original image. As a result, it alleviates the processing burden associated with generating sequences equivalent to the original image size. The results confirm that our proposed scheme is lightweight and secure compared to the latest state-of-the-art image encryption schemes. Additionally, sensitivity analysis demonstrates that the proposed image encryption technique, with a UACI value of 33.48 and NPRC value of 99.96, affirms its resistance to differential attacks.

Frequency-domain image encryption based on IWT and 3D S-box

Most of the existing spatial domain image encryption techniques suffer from the difficulty of resisting cryptographic attacks. For this reason, this paper proposes a frequency-domain based digital image encryption scheme by combining Integer Wavelet Transform (IWT), three-dimensional S-box and chaotic system. First, the plaintext image is decomposed into different frequency subbands by IWT to map the digital image from spatial domain to frequency domain. Second, the plaintext hash value is selected as the dynamic key, and dynamic chaotic pseudo-random sequences with associations are generated, which are used for the encryption of each module respectively. Then, a three-dimensional S-box is designed to encrypt the information-rich low-frequency information using ‘bit-permutation three-dimensional S-box replace ciphertext interleaved diffusion’, while the high-frequency information is encrypted using a lightweight ‘XOR-row column permutation’ operation. Finally, the secure ciphertext for public channel transmission is obtained by the reconstruction method. The scheme of this paper, the frequency domain transformation is implemented through IWT, which enhances the ability to resist attacks. In addition, the diffusion encryption modules employ the introduction of ciphertext interleaved diffusion and parallel encryption mechanisms, thus the algorithm has the ability to resist plaintext attacks. Theoretical analysis and empirical results show that the algorithm has excellent numerical statistical analysis results, which corroborate that it has good confusion, diffusion and avalanche effects, and is able to resist various common cryptographic attacks. The frequency domain image encryption scheme proposed in this paper is a preferred high-security digital image privacy protection technique, so it has good application prospects.

Analysis of Multivariate Encryption Schemes: Application to Dob and $${C}^{*}$$

Analysis of Multivariate Encryption Schemes: Application to Dob and $${C}^{*}$$

Attribute-based key management for patient-centric and trusted data access in blockchain-enabled IoMT

Internet of Medical Things (IoMT) provides real-time data collection and access services to medical entities by connecting their devices to Internet. However, within such a complex architecture, achieving patient-centric data access still presents trustworthiness challenges of transmission security and usage reliability. Ciphertext-policy attribute-based encryption (CP-ABE) and blockchain are both the promising primitives that support patients with secure access control over their data. Nevertheless, both have their unique key management issues. In this paper, we propose a novel patient-centric and trusted data access (PCT-DA) system in blockchain-enabled IoMT. Firstly, we develop an online/offline encryption and verifiable outsourced decryption CP-ABE scheme to relieve the computation pressure on patients and users. Secondly, we design a flexible attribute-based key management mechanism to overcome the security drawbacks of encryption and attribute keys, such as single point of failure, key escrow and privacy leakage. Finally, we build a trusted integrity audit contract to guarantee the incentive fairness between patients and users in access services. Moreover, theoretical analyses prove that the PCT-DA system not only achieves confidentiality, integrity, traceability and forward/backward security, but also guarantees static security under random oracles. Simulation experiments indicate that our proposal reduces the time cost by approximately 14.10 seconds over state-of-the-art and is more practical in blockchain-enabled IoMT system.

High-dimensional Poincaré beams generated through cascaded metasurfaces for high-security optical encryption

Optical encryption plays an increasingly important role in the field of information security owing to its parallel processing capability and low power consumption. Employing the ultrathin metasurfaces in optical encryption has promoted the miniaturization and multifunctionality of encryption systems. Nevertheless, with the few number of degrees of freedom (DoFs) multiplexed by single metasurface, both key space and encoding space are limited. To address this issue, we propose a high-security and large-capacity optical encryption scheme based on perfect high-dimensional Poincaré beams with expanded DoFs. By cascading two arrayed metasurfaces, more beam properties can be independently engineered, which gives rise to the extensively expanded key and encoding spaces. Our work provides a promising strategy for optical encryption with high security level and large information capacity and might facilitate the applications of Poincaré beams in optical communications and quantum information.

Advanced Optical Information Encryption Enabled by Polychromatic and Stimuli-Responsive Luminescence of Sb-Doped Double Perovskites.

The smart materials with multi-color and stimuli-responsive luminescence are very promising for next generation of optical information encryption and anti-counterfeiting, but these materials are still scarce. Herein, a multi-level information encryption strategy is developed based on the polychromatic emission of Sb-doped double perovskite powders (SDPPs). Cs2NaInCl6:Sb, Cs2KInCl6:Sb, and Cs2AgInCl6:Sb synthesized through coprecipitation methods exhibit broadband emissions with bright blue, cyan, and orange colors, respectively. The information transmitted by specific SDPP is encrypted when different SDPPs are mixed. The confidential information can be decrypted by selecting the corresponding narrowband filter. Then, an encrypted quick response (QR) code with improved security is demonstrated based on this multi-channel selection strategy. Moreover, the three types of SDPPs exhibit three different water-triggered luminescence switching behaviors. The confidential information represented by Cs2NaInCl6:Sb can be erased/recovered through a simple water spray/drying. Whereas, the information collected from the green channel is permanently erased by moisture, which fundamentally avoids information leakage. Therefore, different encryption schemes can be designed to meet a variety of encryption requirements. The multicolor and stimuli-responsive luminescence greatly enrich the flexibility of optical information encryption, which leaps the level of security and confidentiality.

Exploiting high-quality reconstruction image encryption strategy by optimized orthogonal compressive sensing

Compressive sensing is favored because it breaks through the constraints of Nyquist sampling law in signal reconstruction. However, the security defects of joint compression encryption and the problem of low quality of reconstructed image restoration need to be solved urgently. In view of this, this paper proposes a compressive sensing image encryption scheme based on optimized orthogonal measurement matrix. Utilizing a combination of DWT and OMP, along with chaos, the proposed scheme achieves high-security image encryption and superior quality in decryption reconstruction. Firstly, the orthogonal optimization method is used to improve the chaotic measurement matrix. Combined with Part Hadamard matrix, the measurement matrix with strong orthogonal characteristics is constructed by Kronecker product. Secondly, the original image is sparsely represented by DWT. Meanwhile, Arnold scrambling is used to disturb the correlation between its adjacent pixels. Following this, the image is compressed and measured in accordance with the principles of compressive sensing and obtain the intermediate image to be encrypted. Finally, the chaotic sequence generated based on 2D-LSCM is used to perform on odd-even interleaved diffusion and row-column permutation at bit-level to obtain the final ciphertext. The experimental results show that this scheme meets the cryptographic requirements of obfuscation, diffusion and avalanche effects, and also has a large key space, which is sufficient to resist brute-force cracking attacks. Based on the sparse and reconstruction algorithm of compressive sensing proposed in this paper, it has better image restoration quality than similar algorithms. Consequently, the compressive sensing image encryption scheme enhances both security and reconstruction quality, presenting promising applications in the evolving landscape of privacy protection for network big data.

A color image encryption scheme based on a 2D coupled chaotic system and diagonal scrambling algorithm

Abstract A novel color image encryption scheme is developed to enhance the security of encryption without increasing the complexity. Firstly, the plain color image is decomposed into three grayscale plain images, which are converted into the frequency domain coefficient matrices (FDCM) with discrete cosine transform (DCT) operation. After that, a two-dimensional (2D) coupled chaotic system is developed and used to generate one group of embedded matrices and another group of encryption matrices, respectively. The embedded matrices are integrated with the FDCM to fulfill the frequency domain encryption, and then the inverse DCT processing is implemented to recover the spatial domain signal. Eventually, under the function of the encryption matrices and the proposed diagonal scrambling algorithm, the final color ciphertext is obtained. The experimental results show that the proposed method can not only ensure efficient encryption but also satisfy various sizes of image encryption. Besides, it has better performance than other similar techniques in statistical feature analysis, such as key space, key sensitivity, anti-differential attack, information entropy, noise attack, etc.

Drive–response asymptotic shape synchronization for a class of two-dimensional chaotic systems and its application in image encryption

This paper proposes the concept of drive–response asymptotic shape synchronization for two-dimensional chaotic systems and its application in image encryption. It overcomes the limitations of traditional shape synchronization, eliminates the restrictions on the drive system’s continuous differentiability, and the response system’s specific format, while simplifying the controller design, thereby demonstrating enhanced applicability and ease of implementation. Moreover, based on the characteristics of asymptotic shape synchronization, we propose a novel image encryption scheme. In this scheme, the drive and response systems, initialized with distinct values, achieve identical chaotic attractors through rotation and translation parameters in rigid transformation, which are utilized for encryption and decryption processes, respectively. Our encryption algorithm employs DNA coding to construct a DNA plane and incorporates the concept of Rubik’s cube rotations for scrambling and diffusion. Experimental simulations and performance analysis verify the effectiveness of the proposed encryption scheme in withstanding various attacks, ensuring a high level of security.

Chaotic Encryption Scheme for Double Grayscale Images using Sprott B Hyperchaotic Map

Image encryption become more significant since most of our data are communicated and stored as digital image form. To warrant high confidentiality, cipher image must be the produced in excellent quality to avoid any information leakage related to the original image. Since image has become one of the most used tools in information exchanges, large production and storage of cipher images are highly demanded, and this scenario could affect the production of high-quality cipher images. While most of existing encryption for images are for single image, processing multiple images simultaneously comes in handy as a fitting fast action to realize the convenience of encryption, storage, and transmission of multiple images. Inspired by those idea, we proposed a new chaotic encryption scheme using Sprott B hyperchaotic map. Using this scheme, two grayscale images are encrypted to produce a single cipher image. The encryption begins with the process of combining two images and encrypting the combined image using the hyperchaotic map. One cipher image will be produced representing and carrying information of the combination of the two images. Our experiments demonstrated significant enhancement offered by the scheme, while maintaining the quality of the recovered plain image. The proposed scheme yields cipher image with excellent quality in terms of noise-like visual of which the information of the images is concealed. While the proposed scheme satisfies the requirements of producing cipher images with excellent quality, it also achieves the credibility to decrypt the cipher image and restoring the plain image exactly similar to the original image.

Lynx: Family of Lightweight Authenticated Encryption Schemes Based on Tweakable Blockcipher

Lynx: Family of Lightweight Authenticated Encryption Schemes Based on Tweakable Blockcipher

S-box design based on logistic skewed chaotic map and modified Rabin-Karp algorithm: applications to multimedia security

A substitution box (S-box) serves as the nonlinearity component in a symmetric key encryption scheme; it directly determines the performance and security level of ciphers. Thus, the construction of an S-box with superior performance and efficiency, specifically in terms of high cryptographic properties, is critical. This research proposes a novel method to construct the S-box using the skewed logistic chaotic map and modified Rabin-Karp rolling hash function without disturbing its mathematical structure. First, iterate the skewed logistic map by selecting a seed value and specifying the parameters to generate the chaotic values. The map’s sensitivity to initial conditions and parameters results in a seemingly random and unpredictable chaotic values. Second, hash the chaotic values using Rabin-Karp for generating sequences of numbers within a specific range (0–255 for an 8-bit S-box). Then an S-box is constructed using the hash values. Performance evaluations indicate that the S-box produced through our suggested approach exhibits superior performance, demonstrating robust resistance against various security threats, including but not limited to linear attacks, differential attacks, and others. To demonstrate the effectiveness of the constructed S-box, this paper goes on to employ it in an image encryption application. Security analyses reveal that the developed image encryption algorithm successfully encrypts diverse types of images, producing cipher images characterized by uniformly distributed histograms. Performance assessments illustrate its high-security level, surpassing several state-of-the-art encryption algorithms.

A Certificateless Verifiable Bilinear Pair-Free Conjunctive Keyword Search Encryption Scheme for IoMT

With superior computing power and efficient data collection capability, Internet of Medical Things (IoMT) significantly improves the accuracy and convenience of medical work. As most communications are over open networks, it is critical to encrypt data to ensure confidentiality before uploading them to cloud storage servers (CSSs). Public key encryption with keyword search (PEKS) allows users to search for specific keywords in ciphertext and plays an essential role in IoMT. However, PEKS still has the following problems: 1. As a semi-trusted third party, the CSSs may provide wrong search results to save computing and bandwidth resources. 2. Single-keyword searches often produce many irrelevant results, which is undoubtedly a waste of computing and bandwidth resources. 3. Most PEKS schemes rely on bilinear pairings, resulting in computational inefficiencies. 4. Public key infrastructure (PKI)-based or identity-based PEKS schemes face the problem of certificate management or key escrow. 5. Most PEKS schemes are vulnerable to offline keyword guessing attacks, online keyword guessing attacks, and insider keyword guessing attacks. We present a certificateless verifiable and pairing-free conjunctive public keyword searchable encryption (CLVPFC-PEKS) scheme. An efficiency analysis shows that the performance advantage of the new scheme is far superior to that of the existing scheme. More importantly, we provide proof of security under the standard model (SM) to ensure the reliability of the scheme in practical applications.

Verifiable Encryption from MPC-in-the-Head

Verifiable encryption (VE) is a protocol where one can provide assurance that an encrypted plaintext satisfies certain properties, or relations. It is an important building block in cryptography with many useful applications, such as key escrow, group signatures, optimistic fair exchange, and others. However, the majority of previous VE schemes are restricted to instantiation with specific public-key encryption schemes or relations. In this work, we propose a novel framework that realizes VE protocols using zero-knowledge proof systems based on the MPC-in-the-head paradigm (Ishai et al. STOC 2007). Our generic compiler can turn a large class of zero-knowledge proofs into secure VE protocols for any secure public-key encryption scheme with the undeniability property, a notion that essentially guarantees binding of encryption when used as a commitment scheme. Our framework is versatile: because the circuit proven by the MPC-in-the-head prover is decoupled from a complex encryption function, the work of the prover is focused on proving the encrypted data satisfies the relation, not the proof of plaintext knowledge. Hence, our approach allows for instantiation with various combinations of properties about the encrypted data and encryption functions. We then consider concrete applications, to demonstrate the efficiency of our framework, by first giving a new approach and implementation to verifiably encrypt discrete logarithms in any prime order group more efficiently than was previously known. Then we give the first practical verifiable encryption scheme for AES keys with post-quantum security, along with an implementation and benchmarks.

On the Security of Key-Aggregate Searchable Encryption

The sharing of encrypted data in cloud computing is an essential functionality with countless applications in our everyday life. However, the issue of how to securely, efficiently and flexibly share encrypted data in multi-user settings has not been well solved. As a promising and elegant technique, the key-aggregate searchable encryption (KASE) scheme can efficiently support selective sharing of a large number of documents with a set of users using only a single, constant-size authorization key (i.e., the aggregated key). However, by conducting cryptanalysis on existing KASE schemes, we classify the attack methods into two types: offline keyword guessing attacks and authorization abuse. For the former attacks, we first employ the known keyword guessing attack methods to cryptanalyze several existing KASE schemes. Furthermore, we propose two novel keyword guessing attack methods, namely (1) Keyword guessing attack by modifying ciphertext and (2) Keyword guessing attack by constructing verification equation. For the latter attacks, we first utilized the known authorization abuse attack methods to cryptanalyze several existing KASE schemes. Furthermore, we develop a novel attack method in which the attacker can independently upgrade their own authorization and gain enhanced search privileges without colluding with multiple authorized users.

Attribute Based Signature Encryption Scheme Based on Cloud Computing in Medical Social Networks

The emergence of mobile medical social networks has provided great convenience for patients to communicate with each other about their medical conditions, promoting efficient and high-quality communication and exchange among patients. However, at the same time, it has also raised issues of confidentiality and privacy of patient data. In response to this issue, this article proposes a cloud-based attribute-based signature encryption scheme that can effectively protect the privacy of patient data. The patient encrypts their medical information and uploads it to the cloud server. When the data user wants to access the patient’s information, the cloud server helps the data user partially decrypt and verify the integrity of the data, which to some extent reduces the computational workload of the data user. Meanwhile, under the random oracle model, it has been proven that the scheme satisfies the unforgeability under selective message attacks, indistinguishability under selective cipher text attacks, and attribute privacy security. Theoretical analysis and numerical simulation experiments show that this scheme has higher efficiency than existing schemes in the signing and decryption stages.

Differential-Linear Cryptanalysis of GIFT family and GIFT-based Ciphers

At CHES 2017, Banik et al. proposed a lightweight block cipher GIFT consisting of two versions GIFT-64 and GIFT-128. Recently, there are lots of authenticated encryption schemes that adopt GIFT-128 as their underlying primitive, such as GIFT-COFB and HyENA. To promote a comprehensive perception of the soundness of the designs, we evaluate their security against differential-linear cryptanalysis. For this, automatic tools have been developed to search differential-linear approximation for the ciphers based on S-boxes. With the assistance of the automatic tools, we find 13-round differential-linear approximations for GIFT-COFB and HyENA. Based on the distinguishers, 18-round key-recovery attacks are given for the message processing phase and initialization phase of both ciphers. Moreover, the resistance of GIFT-64/128 against differential-linear cryptanalysis is also evaluated. The 12-round and 17-round differential-linear approximations are found for GIFT-64 and GIFT-128 respectively, which lead to 18-round and 19-round key-recovery attacks respectively. Here, we stress that our attacks do not threaten the security of these ciphers.

Aligning security and energy-efficiency using change detection and partial encryption for wireless camera networks

Wireless camera networks (WCNs) have seen widespread deployment in recent years, leading to an upsurge in monitoring and surveillance systems aimed at detecting foreign objects and changes within remote environments. However, wireless communication remains susceptible to cybersecurity threats, enabling eavesdroppers to access and manipulate confidential multimedia data effortlessly. Moreover, wireless cameras are low-power devices, encounter challenges as many state-of-the-art schemes adopt intricate security mechanisms, resulting in elevated costs, latency, and power consumption. This significantly compromises the stability of the node power and network lifetime and limits the applicability of security schemes in real-time implementations. This study addresses these issues by presenting DyimEnc, a dynamic image encryption scheme, to establish secure image transmission within wireless camera networks. The proposed scheme dynamically implements a security, complexity, and power consumption trade-off based on the currently available resources in each camera node. In the DyimEnc scheme, an effective in-node change-detection method is used to detect changes in the captured images and reduce the false transmission of images across the network. Additionally, a dynamic lightweight partial-encryption method is proposed to encrypt the edge maps of sensitive images that include changes. Moreover, a flexible key-management method is proposed for image encryption and transmission. Simulation results underscore DyimEnc's substantial impact, revealing significant reductions in power consumption, encryption cost, and transmission latency. It effectively achieves an average throughput of 254.9 KB/s and a remarkable 48 % decrease in network power consumption, showcasing a substantial 59 % improvement compared to a related study. Security analysis proved the robustness of our scheme in resisting attacks and satisfying the security requirements of WCNs.

Biometric identification on the cloud: A more secure and faster construction

Cloud-assisted biometric identification can benefit data owners with limited resources by offloading their storage and identification tasks to cloud servers with abundant resources. However, the adoption of this computing paradigm is hindered by security and privacy concerns. To solve the dilemma, several privacy-preserving cloud-assisted biometric identification protocols have been proposed. Nevertheless, the existing designs suffer from one or more of the following restrictions: (1) support only for data owner-online query, (2) low security level, and (3) inefficiency. Motivated by these challenges, this paper aims to explore a more secure and efficient construction. Concretely, we initialize the error weighted hashing (EWH)-based data packing technique to replace the time-consuming linear scan search during the identification process. Additionally, to ensure compatibility with the EWH-based search algorithm, we formulate an identity (id)-based scoring strategy and introduce a random split-based data encryption algorithm, which circumvents the costly homomorphic encryption scheme. Within the framework of the two non-colluding servers model, the random split-based one-time pad encryption guarantees provably indistinguishable security against chosen-plaintext attacks. Finally, since only simple hash and xor operations are involved, our novel construction exhibits significantly improved performance compared to prior designs, both in theory and in practice. This superiority is validated through rigorous theoretical analysis and extensive experimental evaluation.

A new self-embedding digital watermarking encryption scheme

A new self-embedding digital watermarking encryption scheme