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This paper conducts a security analysis on an image encryption scheme that incorporates chaos synchronization and DNA encoding techniques. The scheme adheres to the typical Substitution–Permutation structure by introducing the DNA operation as a nonlinear component. Compared to the traditional chaotic ciphers, the designer claims that the scheme achieved better nonlinear properties through the DNA operation. However, the characteristics of the differential between some pairs of plaintexts and the corresponding ciphertexts can be exploited to break the permutation operation. Meanwhile, the substitution operation can also be cracked by checking the mapping between the intermediate variables inversely permuted from ciphertext and the corresponding plaintext. Given the weaknesses of the encryption scheme, we introduce effective strategies for the known-plaintext attack. Both rigorous theoretical analyses and detailed experimental results are provided to demonstrate the effectiveness of the attacks. [ABSTRACT FROM AUTHOR]

Unmanned aerial vehicles (UAVs) have gained significant attention in robotics research during the past decade, despite their presence dating back to 1915. Unmanned Aerial Vehicles (UAVs) are capable of efficiently and successfully carrying out a range of tasks. As a result, the use of many UAVs to fulfill a specific mission has grown into a popular area of research. Researchers have conducted investigations on the use of numerous UAVs in various fields such as remote sensing, disaster relief, force protection, military warfare, and surveillance. Efficiency and robustness are crucial factors for carrying out key operations. Multiple groups of UAVs, through appropriate interaction and concerted procedures, can achieve these objectives. The unpredictable features of UAVs and their reliance on unprotected and widely available wireless networks create challenges in establishing secure communication between a private edge cloud and a UAV. Consequently, secret UAV networks that utilize edge computing necessitate supplementary precautions to safeguard their networks. This research paper talks about a simple, lightweight, certificate-free, heterogeneous online/offline aggregate signing scheme called CL-PFASC. It comes from the discrete logarithm problem. The concert scheme enables UAVs to communicate with a GS without the need for a bilinear coupling operation. We classify the UAVs as identity-based cryptography (IBC) and the ground station GS as public-key infrastructure (PKI). We verify the security features of the suggested scheme using a formal security evaluation method, the random oracle model, under confidentiality and unforgeability. We also evaluate its communication and computation costs and compare them to those of similar existing schemes. The performance and security study indicate that the suggested approach improves both efficiency and security.

In recent years, various chaotic image encryption algorithms have been proposed, but their security issues still need to be studied and reviewed. This paper implements a cryptographic security analysis on a color image encryption algorithm based on bit-level and improved one-dimensional chaotic map (CIEA-IOCM). In CIEA-IOCM, using the pseudo-random sequences generated by an improved one-dimensional chaotic map, bit-level permutation-diffusion and linear transformation are successively performed to get its cipher image from a plain image. Based on some seemingly good performance analysis results, CIEA-IOCM claimed that it can withstand various common attacks. However, after a cryptanalysis, we found that it can be completely cracked by a chosen-plaintext attack method. The most essential reason is that there are equivalent keys for both bit-level permutation and diffusion processes, and its linear transformation can be combined and simplified. Thus, we achieved a successful security attack by obtaining the equivalent keys. Moreover, the experimental results verify the effectiveness and efficiency of our method. Therefore, our research work can provide some positive and valuable references for improving the security of chaotic image encryption algorithms. [ABSTRACT FROM AUTHOR]

This paper proposes two attack methods to break the encryption algorithm using minimax differential evolution-based 7D hyper-chaotic map. In attack method 1, the secret keys generated by the 7D hyper-chaotic map can be directly revealed through two pairs of plain/cipher images. Once the secret keys are known, any cipher image can be decrypted easily. In attack method 2, we build three dictionary matrices of R, G and B channels firstly, and the corresponding plain image pixel value can be queried in the dictionary matrix one by one without using the secret keys or any system parameter. Experimental results demonstrate that the cryptosystem can be broken successfully by either of the proposed methods, thus avoiding the potential unexpected loss caused by the use of insecure encryption schemes. [ABSTRACT FROM AUTHOR]

An Image Encryption Algorithm with the Quantum logistic and lorenz Chaotic map, and DNA Coding (IEA-QCDC) was proposed. Relying on some empirical analyzes and experimental results, the designers of IEA-QCDC claimed that this strategy can led to a significant enhancement in reliability and security. However, we investigate the essential properties of IEA-QCDC, and then propose an efficient chosen-plaintext attack to crack its equivalent permutation and diffusion key. By analyzing the encryption effect of continuous DNA encryption operations, the mathematical properties of some DNA codes were summarized. In addition, we find out that the iterative sequence obtained by the non-chaotic state is not even resistant to only-ciphertext attacks by analyzing the Lyapunov exponent and bifurcation diagrams of the quantum Logistic map. Aiming at the security vulnerabilities existing in IEA-QCDC, suggestions are put forward to improve the security and practicability of encryption algorithms, which will promote the development of cryptographic design to a certain extent. [ABSTRACT FROM AUTHOR]

Chaos-based cryptosystems are considered a secure mode of communication due to their reliability. Chaotic maps are associated with the other domains to construct robust encryption algorithms. There exist numerous encryption schemes in the literature based on chaotic maps. This work aims to propose an attack on a recently proposed hyper-chaotic map-based cryptosystem. The core notion of the original algorithm was based on permutation and diffusion. A bitlevel permutation approach was used to do the permutation row-and column-wise. The diffusion was executed in the forward and backward directions. The statistical strength of the cryptosystem has been demonstrated by extensive testing conducted by the author of the cryptosystem. This cryptanalysis article investigates the robustness of this cryptosystem against a chosen-plaintext attack. The secret keys of the cryptosystem were retrieved by the proposed attack with 258 chosen-plain images. The results in this manuscript suggest that, in addition to standard statistical evaluations, thorough cryptanalysis of each newly suggested cryptosystem is necessary before it can be used in practical application. Moreover, the data retrieved is also passed through some statistical analysis to compare the quality of the original and retrieved data. The results of the performance analysis indicate the exact recovery of the original data. To make the cryptosystem useful for applications requiring secure data exchange, a few further improvement recommendations are also suggested. [ABSTRACT FROM AUTHOR]

Cryptanalysis is important to the design of image cryptographic system. Recently, a two-round image cryptographic system is proposed and the authors claim that it is security. However, we find that the diffusion equation causes certain cipher images to appear period. According to this feature, we analyze one-round encryption by chosen-plaintext attack at first. And the encrypted image is successfully cracked. Then, we analyze two-round encryption in the same way. Although the encrypted image cannot be fully cracked, some equivalent keys are obtained. To remedy the loophole, the original encryption scheme is improved and the security analysis is performed. Experiments show that the improved cryptosystem can better resist chosen-plaintext attack while maintaining the same encryption performance as the original encryption scheme. [ABSTRACT FROM AUTHOR]

Recently, an efficient pixel-level chaotic image encryption algorithm has been proposed. In this encryption algorithm, they adopted a permutation-rewriting-diffusion (PRD) encryption structure, which enhanced the relationship between permutation and diffusion. At the same time, the generation of the keystream is related to the pixels square sum of the plaintext image. However, there are still two security risks in their encryption scheme. First, both the rewriting and the diffusion operations are performed by modular addition, which makes the two operations equivalent to one-step diffusion operation. Second, the rewriting parameters and the diffusion matrix are both independent of the plaintext. Therefore, the rewriting-diffusion process can be represented by an equivalent modular addition formula, and the PRD structure is equal to the classic PD structure. The separate attack method is used in this paper to crack the encryption scheme. At first, the equivalent diffusion process is cracked by performing the modulo subtraction operation on the target deciphered image and the cipher-text of an all-zero image. Then, the permutation rule is deciphered by constructing several images with the same square sum of pixels. In addition, some improvements for Ye' s encryption scheme are provided to enhance the security. [ABSTRACT FROM AUTHOR]

Recently, an image encryption scheme based on a 2D hyperchaotic map is proposed. It adopts the permutation–diffusion architecture and consists of three steps, which are permutation, forward diffusion, and backward diffusion. In this paper, we break this cipher with both the chosen-plaintext attack (CPA) and the chosen-ciphertext attack (CCA). According to our analysis, we found the two complex diffusion processes could be simplified into two simple diffusions and a modular addition operation. Based on this, the equivalent key can be obtained with CPA and CCA. Detailed theoretical derivations and the results of experiments confirmed the feasibility of our attack methods. When the image size was 256 × 256 , the running time of the attacks was less than 2 hours on a laptop with a 2.59 GHz Intel Core i7 and 16 GB DDR3 memory. Other sizes of images were also tested, and some rules were found. In addition, the probability of other attacks has also been discussed, and some suggestions for improvements are given. The source codes are publicly available and can be found online. [ABSTRACT FROM AUTHOR]

The Cloud Computing Environment (CCE) developed for using the dynamic cloud is the ability of software and services likely to grow with any business. It has transformed the methodology for storing the enterprise data, accessing the data, and Data Sharing (DS). Big data frame a constant way of uploading and sharing the cloud data in a hierarchical architecture with different kinds of separate privileges to access the data. With the requirement of vast volumes of storage area in the CCEs, capturing a secured data access framework is an important issue. This paper proposes an Improved Secure Identification-based Multilevel Structure of Data Sharing (ISIMSDS) to hold the DS of big data in CCEs. The complex file partitioning technique is proposed to verify the access privilege context for sharing data in complex CCEs. An access control Encryption Method (EM) is used to improve the encryption. The Complexity is measured to increase the authentication standard. The active attack is protected using this ISIMSDS methodology. Our proposed ISIMSDS method assists in diminishing the Complexity whenever the user's population is increasing rapidly. The security analysis proves that the proposed ISIMSDS methodology is more secure against the chosen-PlainText (PT) attack and provides more efficient computation and storage space than the related methods. The performance of the proposed ISIMSDS methodology provides more efficiency in communication costs such as encryption, decryption, and retrieval of the data. [ABSTRACT FROM AUTHOR]

In 2019, a chaotic image encryption scheme based on a variant of the Hill cipher (VHC-CIES) was proposed by the Moroccan scholars. VHC-CIES introduces a Hill cipher variant and three improved one-dimensional chaotic maps to enhance the security. In this paper, we conduct a comprehensive cryptanalysis, and find that VHC-CIES can resist neither chosen-plaintext attack nor chosen-ciphertext attack due to its inherent flaws. When it comes to chosen-plaintext attack, firstly, we select a plaintext with the pixel values are all 0 and its corresponding ciphertext, and then use algebraic analysis to obtain the equivalent key stream for cracking VHC-CIES. Secondly, we select a plaintext which the pixel values are invariably 1 and obtain its corresponding ciphertext to obtain some Hill cipher variant parameters of VHC-CIES. Finally, we use the resulting steps of the first two to recover the original plain image from a given target cipher image. Similarly, a chosen-ciphertext attack method can also break VHC-CIES. Theoretical analysis and experimental results show that both chosen-plaintext attack and chosen-ciphertext attack can effectively crack VHC-CIES with data complexity of only O (2). For color images of size 256 × 256 × 3 , when our simulation encryption time is 0.3150 s, the time for complete breaking by chosen-plaintext attack and chosen-ciphertext attack is about 0.6020 s and 0.9643 s, respectively. To improve its security, some suggestions for further improvement are also given. The cryptanalysis work in this paper may provide some reference for the security enhancement of chaos-based image cryptosystem design. [ABSTRACT FROM AUTHOR]

Many encryption algorithms are designed to decrease the probability of cyberattacks by assuring data security as well as system and participant authentication. However, in the development of computer resources cryptanalytical techniques have been developed and performed competitively in information security with good results. In this paper, we reported security flaws in the recently offered encryption technique based on a chaotic map for Internet of Health Things (IoHT) security. The scheme was based on a new chaotic map, modified Mandelbrot set, and conditional shift algorithm asserting the encryption algorithm is secure. We have performed some cryptographic attacks to retrieve the key from the understudy cryptosystem. The key was retrieved in little computation by using a chosen-plaintext attack and one known plaintext ciphertext pair. The minimum execution time of performed attacks indicates the vulnerability of the diffusion-based encryption algorithm. To enhance the security of the understudy cryptographic algorithm, we have also suggested certain improvements.

The security system engaged to transfer securely the sensitive information over wireless channels must posses some innate features such as high resistivity to various cryptographic attacks, high sensitivity to secret key and plaintext, and strong statistical characteristics of encrypted content. Recently, an image cryptosystem is investigated to secure color images while transmission. The cryptosystem is based on permutation only cipher and employed synchronized 4D hyperchaotic systems. The cryptosystem has credibility of providing ample statistical encryption quality of ciphertext. This paper aims to investigate and analyze the security of this image cryptosystem in terms of its defects and attack resistivity. The security analysis uncovers that cryptosystem holds certain serious security defects and incapable to secure encrypted content. To support the claim, the inherent defects are highlighted; thereby an attack procedure is proposed to show that the cryptosystem is breakable under the proposed cryptanalysis. The attacker can recover complete plaintext image from ciphertext image without knowing secret key. Computer simulations are performed to justify the success of cryptanalysis. The image cryptosystem is all insecure for use in practical applications of image-based secure wireless communication. As a remedy, this paper also suggests security enhancements and an enhanced cryptosystem is proposed to make it completely resistive against above and other types of cryptanalytic attacks and increase on its plain image sensitivity and statistical encryption strength.

In current years many chaos-based Substitution boxes (S-boxes) have been proposed. Recently, an image encryption technique based on multiple chaotic S-box was offered. This encryption method was based on the concept of confusion only produced by the implementation of the S-box. The concept of confusion utilized in the understudy technique can be smashed by using just one chosen-plaintext attack and a chosen-ciphertext attack. This article presents a detailed structure of two types of cryptographic attacks on the diffusion-based encryption scheme. The proposed attacks are successfully performed to retrieve the key with very little execution time by using just one chosen image which indicates the vulnerability of multiple chaotic S-boxes-based cryptosystems. The retrieved data is passed through some statistical analysis such as correlation, histogram, and entropy to check the correctness of recovered data.

In order to improve the security and efficiency of image encryption, many researchers have continuously proposed new image encryption schemes in recent years. However, these image encryption schemes have not been fully analyzed and evaluated. In this paper, a newly reported image encryption scheme based on Feistel network and dynamic Deoxyribonucleic Acid (DNA) encoding is deeply and comprehensively investigated. This encryption scheme mainly adopts four encryption steps to encrypt the plain image, which are Generation of chaotic sequences, Hill encryption, Feistel network, and Pixel diffusion. Our analyses show that there are some problems in the secret key design and encryption process of this encryption scheme. After pointing out and analyzing these problems, we have made several necessary improvements to this encryption scheme and proposed the corresponding chosen-plaintext attack algorithm. The subsequent simulation tests and analyses have confirmed the effectiveness and feasibility of the proposed attack algorithm. Finally, for the problems in this encryption scheme and some current image encryption schemes, improvement suggestions are presented to provide references for the designers of future image encryption schemes.

Recently, an encryption technique depending on discrete dynamical chaotic maps and Brownian motion was offered. The authors of the understudy cryptosystem claim the security of encryption structure by some statistical analysis. We report cryptanalysis of a recently proposed scheme by using some cryptographic attacks. The attacks performed in this work are chosen-plaintext attack, known-plaintext attack, and chosen-ciphertext attack. The offered procedure is cryptanalyzed by taking just one chosen-plain image, one chosen-cipher image, and only one pair of plaintext and ciphertext, which shows the scheme's vulnerability. Moreover, we have offered an improved cryptosystem depending on the Basin chaotic map, Gingerbread man map, and Brownian motion, providing a robust security level. [ABSTRACT FROM AUTHOR]

Security is a key problem for the transmission, interchange, and storage process of multimedia systems and applications. In 2018, Li et al. proposed in-depth security analysis on an image encryption algorithm based on a first-order time-delay system (IEATD) and gave a specific chosen-plaintext attack on it. Moreover, an enhanced version called as IEACD was designed to fix the reported security defects. This article analyzes the essential structures of the two algorithms and evaluates their real security performances: 1) no efficient nonlinear operations are adopted to assure the sensibility of keystream; 2) the equivalent secret key of IEATD can be efficiently recovered from one known plain-image and the corresponding cipher-image; and 3) IEACD can still be efficiently cracked with a chosen-plaintext attack. Both rigorous theoretical analyses and detailed experimental results are provided to demonstrate effectiveness of the advanced cryptanalytic methods. [ABSTRACT FROM AUTHOR]

Recently, a new secure image encryption scheme was proposed based on a novel 2D sine–cosine cross‑chaotic map. The authors claimed that the encryption scheme they proposed was secure enough to resist all the existing cryptanalytic attacks. However, the multi-round original cryptosystem with permutation–bit diffusion structure (PBDS) was found to have three security vulnerabilities and was proved to be equivalent to the one-round cryptosystem with PBDS, which would lead to the original cryptosystem being successfully cracked by chosen-plaintext attack (CPA). Subsequently, two efficient and feasible attack schemes were proposed in this paper, and they require log 2 W × H + 1 and log 256 W × H + 1 times of CPA in total, respectively. Simulation and experimental results have verified the effectiveness and feasibility of the two attack schemes. [ABSTRACT FROM AUTHOR]

HHL algorithm is a quantum algorithm for solving linear equation system. It can achieve an exponential improvement over the best classical algorithm. In this paper, we analyze the quantum security of Grain-128/Grain-128a stream cipher by using the HHL algorithm. Our algorithm is based on Chen and Gao's research on solving nonlinear equation system in Chen et al. (Quantum algorithm for optimization and polynomial system solving over finite field and application to cryptanalysis, 2018. arXiv:1802.03856) and Chen et al. (Quantum algorithms for Boolean equation solving and quantum algebraic attack on cryptosystems, 2017. arXiv:1712.06239). Firstly, we build a nonlinear Boolean equation system by choosing any keystream. Then, the nonlinear equation system is transformed into a special linear equation system that can be solved with the HHL algorithm. Finally, we solve the system by the HHL quantum algorithm. Our attack requires N > 2 8 -bit keystream, and the complexity is O (2 21 N 3.5 κ 2 e ϵ / ϵ 0.5) for Grain-128, and O (2 21.5 N 3.5 κ 2 e ϵ / ϵ 0.5) for Grain-128a where κ is the condition number of the matrix of the corresponding linear systems and ϵ is a given error bound. Then we give a toy example of Grain family to estimate κ and briefly analyze the security of Grain-128/Grain-128a against HHL algorithm. [ABSTRACT FROM AUTHOR]

As we know, improving security is one of the most important motivations for designing new image encryption schemes. However, the security of some new image encryption schemes has not been fully analyzed and evaluated. In view of this, a novel image encryption scheme based on the pixel-level filtering and the DNA-level diffusion (PFDD) is analyzed and evaluated in this paper. After comprehensive analysis and study, we find that PFDD does not have its claimed ability to resist chosen-plaintext attacks (CPAs). Therefore, under the conditions of CPAs, we cryptanalyze the entire encryption process of PFDD, and successfully crack it by our proposed attack algorithm. Then, The effectiveness and feasibility of the proposed attack algorithm are verified theoretically and experimentally. Finally, for several representative problems in current chaotic image encryption schemes, we put forward some improvement suggestions for future researchers.

This paper presents an efficient and secure chaotic S-Box based image encryption algorithm. Firstly, by cryptanalyzing a multiple chaotic S-Boxes based image encryption algorithm, we successfully cracked the cryptosystem by using chosen-plaintext attack (CPA). Secondly, we put forward a new image encryption scheme based on a novel compound chaotic map and single S-Box. In the new scheme, a novel discrete compound chaotic system, Logistic-Sine system (LSS), is proposed, which has wider chaotic range and better chaotic properties. And a new S-Box is constructed by using LSS, which has satisfactory cryptographic performance. Based on the new S-Box and the chaotic key stream, the new image encryption algorithm is designed, which consist of a round of permutation and two rounds of substitution process. The permutation and substitution key sequences are related to the plaintext image content, this strategy enables the cryptosystem to resist CPA. The simulation results and security analysis verified the effectiveness of the proposed image encryption scheme. Especially, the new scheme has obvious efficiency advantages, showing that it has better application potential in real-time image encryption.

This paper analyzed the security of an image encryption algorithm based on compound chaotic sequence, the proposed algorithm adopted three-level encryption structure of permutation-forward diffusion-reverse diffusion. Due to the forward diffusion and the reverse diffusion used the same one-dimensional diffusion sequence, therefore, this paper simplified the two level encryption structure of the forward diffusion and reverse diffusion to one-level diffusion encryption structure, further, simplified the three-level encryption structure of permutation-forward diffusion-reverse diffusion to two-level encryption structure of permutation and diffusion. Moreover, the chaotic sequences generated by the encryption algorithm were independent of the plaintext images or ciphertext images, consequently, it could crack the corresponding equivalent diffusion keys and equivalent permutation keys by chosen-plaintext attack. Theoretical analysis and numerical simulation experiment results verify the effectiveness of the analytical method. Finally, this paper proposed some improved suggestions for the original encryption algorithm to promote the security. [ABSTRACT FROM AUTHOR]

Recently, a new image encryption-scheme for embedded systems based on continuous third-order hyperbolic sine chaotic system, has been proposed. The cryptosystem's main objective was to provide a lightweight cryptographic application for use in embedded systems, especially on a UAV (unmanned aerial vehicle) program. In this paper, we scrutinized the design and structure of this cryptosystem, and we evaluated its immunity against usual attacks (e.g., chosen-plaintext attack, differential attack, known-plaintext attack). The system was proven to be weak against the differential attack with only two required chosen plain-images, and against the chosen-plaintext attack with only one 3 × 400 pixel image. A brief description of the feasibility of a known-plaintext attack was given as well. To address these vulnerabilities, some recommendations are drawn in order to be considered for enhancing the underlying scheme or for further proposals to avoid the outlined weaknesses. [ABSTRACT FROM AUTHOR]

Recently, a novel image encryption based on Arnold scrambling and Lucas series has been proposed in the literature. The scheme design is based on permutation-substitution operations, where Arnold map is used to permute pixels of the image for T rounds, and Lucas sequence is used to mask the image and substitute pixel's values. The authors of the cryptosystem have already tested their system against several statistical tests to show its robustness from a statistical view. This cryptanalytic paper scrutinizes the security of this cryptosystem in order to evaluate its immunity against conventional attacks. The results and methods adopted in this paper show that besides the statistical tests, we may need a deep cryptanalysis of every newly proposed cryptosystem before possible adoption in real applications. Those security results should be considered in further proposals. [ABSTRACT FROM AUTHOR]

Fairly recently, a new audio encryption scheme has been proposed. The cryptosystem is based on a substitution-permutation algorithm using DNA encoding. The key-generation of this proposed scheme is based on a key chaining mode, that generates a new key block for every plain block using the chaotic logistic map. After several statistical tests, handled by the authors of the scheme, they claimed that their cryptosystem is robust. In this paper, we scrutinize the cryptosystem from a cryptanalytic perspective, and we handle several security attacks to evaluate the immunity of the system, and to assess its possible adoption in real-world applications. We demonstrate two successful conventional attacks on the scheme, which are: the chosen ciphertext and chosen-plaintext attacks. The cryptosystem's shuffling process design is scrutinized as well, and a cycle attack is described using the drawn results. Lessons learned from this cryptanalytic paper, are then outlined in order to be considered in further designs and proposals. [ABSTRACT FROM AUTHOR]

According to the research works of the literatures on chaotic cryptanalysis, many recent chaotic image encryption algorithms cannot resist chosen-plaintext attack. Although some chaotic image encryption algorithms introduce plain-image information, they still violate some design requirements of modern cryptosystems. Therefore, after analyzing many literatures related to chaotic image encryption, we propose a plain-image-related chaotic image encryption algorithm based on the deoxyribonucleic acid (DNA) sequence operation and discrete logarithm. As we know, the discrete logarithm calculation is a complex non-linear calculation, introducing it can increase the complexity of the encryption process. More importantly, discrete logarithm values are significantly different under different generators, and the multiplicative group adopted in the proposed algorithm has as many as 128 generators. Therefore, by using two generators determined by the secret key and the hash value of the plain-image respectively, we not only expand the key space, but also greatly improve the plain-image sensitivity and plain-image relevancy of the encryption process. In addition, the proposed algorithm improves the way of using the hash value of the plain-image. In this way, once the secret key is selected, chaotic sequences can be generated in advance and reused to improve the encryption efficiency. Similarly, the proposed algorithm also introduces the DNA sequence operation with high parallelism to further improves the encryption efficiency. Simulation tests and comparative analyses show that the proposed algorithm can not only resist common attacks, but also outperform some recent chaotic image encryption algorithms in many aspects.

Recently, a novel bit-level color image encryption scheme based on improved one-dimension (1D) chaotic map has been proposed. It was claimed that the proposed scheme is secure due to the improved 1D chaotic map with better chaotic performance. Some security analyses and simulation experiments were presented to show that it could resist various attacks. However, we found that there are some security loopholes in the original scheme, and then proposed an effective attack strategy utilizing chosen-plaintext attack (CPA) in this paper. The proposed strategy mainly includes two attacks. The first is to obtain the equivalent secret key of the diffusion right shift phase, and the second is to obtain the permutation right shift rule. The effectiveness and feasibility of the proposed method are verified by both theoretical analyses and experimental results. Some proposals are also given for improving the security of the original encryption scheme.

In this paper, a five-dimensional discrete hyperchaotic map is constructed by combining Logistic map and 3D discrete Lorenz map. Based on this chaotic system, a block-based image encryption scheme related to plaintext is designed. The encryption scheme includes scrambling operation and diffusion operation. In the scrambling operation, the scrambling sequence is related to the pixels of the plaintext image, while in the diffusion operation, two rounds of diffusion are carried out for intra-block diffusion, and the generation of random diffusion sequence is related to a pixel value in the block in each round of diffusion, which makes the algorithm resist chosen-plaintext attack. When the next block is diffused, the generation of the diffusion sequence is related to the first and last pixels of the previous block, which makes the block and block interact with each other and enhances the sensitivity of the algorithm to plaintext. Theoretical analysis and experimental results demonstrate the security and practicability of the cryptosystem.

In recent years, with the rapid development of the network communication, information security issues have become increasingly prominent. As an important carrier of information, image plays an important role in the transmission process. Therefore, lots of image encryption algorithms have been proposed. However, these algorithms are not designed in accordance with the unified security standards and requirements, so there may be a lot of security risks, and what is the worst thing is that some encryption algorithms may be cracked in an acceptable time complexity by some cryptographic analysis. This paper focuses on one of the most influential algorithm proposed by Zhang, which improved Zhu's algorithm. The non-fixed parameter and diffusion-permutation strategy are adopted by Zhang, but there are still problems that cannot resist chosen-plaintext attack and the key space is not enough to resist brute-force attack. We use chosen-plaintext attack to crack Zhang algorithm, and then propose a further improved scheme.

The security system engaged to transfer securely the sensitive information over wireless channels must posses some innate features such as high resistivity to various cryptographic attacks, high sensitivity to secret key and plaintext, and strong statistical characteristics of encrypted content. Recently, an image cryptosystem is investigated to secure color images while transmission. The cryptosystem is based on permutation only cipher and employed synchronized 4D hyperchaotic systems. The cryptosystem has credibility of providing ample statistical encryption quality of ciphertext. This paper aims to investigate and analyze the security of this image cryptosystem in terms of its defects and attack resistivity. The security analysis uncovers that cryptosystem holds certain serious security defects and incapable to secure encrypted content. To support the claim, the inherent defects are highlighted; thereby an attack procedure is proposed to show that the cryptosystem is breakable under the proposed cryptanalysis. The attacker can recover complete plaintext image from ciphertext image without knowing secret key. Computer simulations are performed to justify the success of cryptanalysis. The image cryptosystem is all insecure for use in practical applications of image-based secure wireless communication. As a remedy, this paper also suggests security enhancements and an enhanced cryptosystem is proposed to make it completely resistive against above and other types of cryptanalytic attacks and increase on its plain image sensitivity and statistical encryption strength. [ABSTRACT FROM AUTHOR]

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Searchable encryption (SE) has been a promising technology which allows users to perform search queries over encrypted data. However, the most of existing SE schemes cannot deal with the shared records that have hierarchical structures. In this paper, we devise a basic cryptographic primitive called as attribute-based keyword search over hierarchical data (ABKS-HD) scheme by using the ciphertext-policy attribute-based encryption (CP-ABE) technique, but this basic scheme cannot satisfy all the desirable requirements of cloud systems. The facts that the single keyword search will yield many irrelevant search results and the revoked users can access the unauthorized data with the old or outdated secret keys make this basic scheme not scale well in practice. To this end, we also propose two improved schemes (ABKS-HD-I, ABKS-HD-II) for the sake of supporting multi-keyword search and user revocation, respectively. In contrast with the state-of-the-art attribute-based keyword search (ABKS) schemes, the computation overhead of our schemes almost linearly increases with the number of users’ attributes rather than the number of attributes in systems. Formal security analysis proves that our schemes are secure against both chosen-plaintext attack (CPA) and chosen-keyword attack (CKA) in the random oracle model. Furthermore, empirical study using a real-world dataset shows that our schemes are feasible and efficient in practical applications. [ABSTRACT FROM AUTHOR]

Recently, a color image encryption scheme based on the Sine-Sine chaotic system has been proposed by Wang et al. (Signal Processing 144:444–452, 2018). In their scheme, a private parameter E is defined based on global plain information in hope of resisting the chosen-plaintext attack. However, we find that the private parameter is dependent purely on average intensity of a plain image, thereby leaving an open door for cryptanalysis. In this paper, we propose a collision-based inference algorithm to effectively break Wang's image cipher. Then, in order to enhance the security, we develop a hash-based cryptosystem under the permutation-and-diffusion architecture. We conduct experiments and perform extensive comparative studies.The qualitative and quantitative results demonstrate the effectiveness of the collision-based inference algorithm, and the superiority of the proposed image cipher especially in terms of plaintext sensitivity. [ABSTRACT FROM AUTHOR]

In 2017, an efficient chaotic image cipher with dynamic lookup table driven by bit-level permutation strategy (ICDLT) was proposed (Hu et al. Nonlinear Dyn 87:1359–1375). The chaotic cipher adopts a plaintext-related image encryption mechanism as an efficient measure against chosen-plaintext/ciphertext attack. ICDLT is composed of four basic parts: inter-pixel permutation, sequential addition, intra-pixel permutation and diffusion processes, where two kinds of permutation are both related to the plaintext. Although ICDLT is built on complex nonlinear dynamics, we found that it is still vulnerable against chosen-plaintext attack and its individual sub-keys can be recovered using a divide-and-conquer strategy. Benefiting from the essential structure of ICDLT and the intrinsic properties of Latin square, the proposed attack requires only (8 · N 2 + 256 + n c · (2 · N - 1)) plain images, where N 2 is the size of the image and n c is the number of cipher images that need to be cracked. Furthermore, we summarize a more general framework which is beneficial for cryptanalyzing a class of plaintext-related image ciphers. Finally, we propose an improved scheme based on the designed plaintext-related XOR encryption (PR-XOR) module to enhance the security of ICDLT. Theoretical analysis and experiments prove that the improved scheme not only maintains the excellent statistical performances of the original one, but also can resist various attacks. [ABSTRACT FROM AUTHOR]

Recently, Behzad et al. designed a 1-D chaotic coupled Sine map (CCSM) and a dynamic scrambling process based on the size of blocks and then constructed an image encryption algorithm (CSMIE) based on CCSM and the scrambling method. However, we find that the algorithm cannot be used for secure communication because it cannot resist chosen-plaintext attacks. In this paper, we first analyze the real structure of CCSM generated in a digital computer with limited precision and then propose a chosen-plaintext attack to break CSMIE according to the number of blocks. Moreover, we enhance CSMIE by designing a synchronous scrambling and diffusion mechanism which utilizes a three-dimensional hyper-chaotic system and employs the hash values of the plain-image. A series of simulation experiments are conducted to evaluate our enhanced encryption scheme. The experimental results demonstrate that the enhanced encryption scheme performs well in various test indicators and can resist the chosen-plaintext attack. [ABSTRACT FROM AUTHOR]

Security of image communication is more and more important in many applications such as the transmission of military and medical images. To meet the requirement, a new color image encryption algorithm using a new one-dimension (1D) chaotic map was proposed recently, which can resist various attacks because the range of the new chaotic map is larger than that of the previous ones. In our study, the security of the new original method is analyzed and a novel attack method is proposed. It is demonstrated that the scheme is not secure under chosen-plaintext attack, by which the encrypted image can be successfully converted into the corresponding plaintext image without any error. [ABSTRACT FROM AUTHOR]

Recently, a new color image encryption scheme based on hybrid hyper-chaotic system and cellular automata was proposed. In order to generate different key streams according to different plaintexts, the sum of pixel values of each component of the original color image apart from the secret keys is used to determine the initial value of logistic map for encryption. It was claimed that the scheme can resist kinds of attacks. However, this paper found out three security drawbacks about the original encryption scheme and proposed an effective attack method using chosen-plaintext attack by cryptanalysis. The equivalent permutation key stream can be obtained by adjusting individual pixel values of the chosen plaintexts while keeping the sum of pixel values of each color channel unchanged, and all 256 possibilities of equivalent diffusion key streams can be obtained by using 512 specific chosen plaintexts. In addition, the main stages of the proposed attack method, including breaking diffusion and breaking permutation, are exchangeable. The effectiveness of our method is supported by both theoretical analyses and experimental results.

Recently, a new chaotic image encryption technique was proposed based on multiple discrete dynamic maps. The authors claim that the scheme can provide excellent privacy for traditional digital images. However, in order to minimize the computational cost, the encryption scheme adopts one-round encryption and a traditional permutation–diffusion structure. Through cryptanalysis, there is no strong correlation between the key and the plain image, which leads to the collapse of cryptosystem. Based on this, two methods of chosen-plaintext attacks are proposed in this paper. The two methods require 3 pairs and 258 pairs of plain and cipher images, respectively, to break the original encryption system. The simulation results show the effectiveness of the two schemes.

This paper proposes a more efficient attack method on an image fusion encryption algorithm based on DNA operation and hyperchaos. Although several references have reported some methods to crack the image encryption algorithm, they are not the most efficient. The proposed chosen-plaintext attack method can break the encryption scheme with (4×N/M+1) or (M/(4×N)+1) chosen-plaintext images, which is much less than the number of chosen-plaintext images used in the previous cracking algorithms, where M and N represent the height and width of the target ciphertext image, respectively. The effectiveness of the proposed chosen-plaintext attack is supported by theoretical analysis, and verified by experimental results.

In recent years, reversible data hiding in encrypted images (RDH-EI) has attracted more and more attention, and many RDH-EI algorithms have been proposed. Scholars focus on improving embedded capacity and decreasing bit error rate, but the security issue of algorithms has not been paid enough attention to. However, the security of algorithms is a core problem. Recently, a RDH-EI algorithm based on compressed sensing and discrete wavelet transform is proposed. And considering the watermark embedding position keystream is related to the plain-image, the proposed algorithm is supposed to have high security. However, we find its security flaw, and by using chosen-plaintext attacks and differential cryptanalysis, we can extract all the encryption keys and all the embedding keys with merely 14 spatial images. In particular, compared with other methods, the number of images required in our method is independent of image size, which means that it requires less cost to break the algorithm. Finally, to resist the proposed attack, two improved suggestions are put forward. Simulation results demonstrate that the security of the improved algorithm is enhanced. [ABSTRACT FROM AUTHOR]

Cryptanalysis is significant for the design of secure image cryptosystem. Recently, a chaotic image encryption scheme using two rounds of Latin square-based permutation and diffusion was proposed. Although two-round encryption is used, the cryptosystem has still been cracked successfully by the combined attack using both chosen-plaintext attack (CPA) and chosen-ciphertext attack due to the inherent flaw that the same key was used in both permutation and diffusion phases of each round. Therefore, different keys are used in each encryption phase of the improved cryptosystem. However, in this paper, we further attacked the two-round encryption with different keys using only CPA. By counting the number of the diffused pixels in the first diffusion phase from the processed encrypted image, the first permutation of one pixel is confirmed, and then the whole equivalent key stream of the first permutation can be obtained by limited CPA. Based on this, the key stream of the third permutation phase is obtained in a similar way. Meanwhile, all the mappings of the fourth diffusion are collected by 256 CPA, and 17 possible mappings in average are selected by verification. Finally, the key stream of the second diffusion is obtained using two pairs of chosen images. Experiments show that the encrypted image can be cracked successfully by the proposed attack. This work is instructive to the cryptanalysis of multi-round encryption. In order to remedy the security weakness, an improved cryptosystem is also proposed, followed by thorough security analysis. [ABSTRACT FROM AUTHOR]

This paper analyzes the security of image encryption systems based on bit plane extraction and multi chaos. It includes a bit-level permutation for high, 4-bit planes and bit-wise XOR diffusion, and finds that the key streams in the permutation and diffusion phases are independent of the plaintext image. Therefore, the equivalent diffusion key and the equivalent permutation key can be recovered by the chosen-plaintext attack method, in which only two special plaintext images and their corresponding cipher images are used. The effectiveness and feasibility of the proposed attack algorithm is verified by a MATLAB 2015b simulation. In the experiment, all the key streams in the original algorithm are cracked through two special plaintext images and their corresponding ciphertext images. In addition, an improved algorithm is proposed. In the improved algorithm, the generation of a random sequence is related to ciphertext, which makes the encryption algorithm have the encryption effect of a “one time pad”. The encryption effect of the improved algorithm is better than that of the original encryption algorithm in the aspects of information entropy, ciphertext correlation analysis and ciphertext sensitivity analysis.

Based on orthogonal Latin cubes, an image cryptosystem with confusion–diffusion–confusion cipher architecture has been proposed recently (Inf. Sci.2019, 478, 1–14). However, we find that there are four fatal vulnerabilities in this image cryptosystem, which leave open doors for cryptanalysis. In this paper, we propose a reference-validation inference algorithm and design screening-based rules to efficiently break the image cryptosystem. Compared with an existing cryptanalysis algorithm, the proposed method requires fewer pairs of chosen plain-cipher images, and behaves stably since different keys, positions of chosen bits and contents of plain images will not affect the cryptanalysis performance. Experimental results show that our cryptanalysis algorithm only requires 8×H×W3+3 pairs of chosen plain-cipher images, where H×W represents the image’s resolution. Comparative studies demonstrate effectiveness and superiority of the proposed cryptanalysis algorithm.

In this paper, we construct a five dimensional continuous hyperchaotic system and propose an image encryption scheme based on the hyperchaotic system, which adopts DNA dynamic coding mechanism and classical scrambling diffusion encryption structure. In the diffusion stage, two rounds of diffusion are adopted and the rules of DNA encoding (DNA decoding) are dynamically changed according to the pixel value of the plaintext image, that is, the rules of DNA encoding (DNA decoding) used to encrypt different images are different, which makes the algorithm can resist chosen-plaintext attack. The encryption (decryption) key is only the initial value of the chaotic system, which overcomes the difficulty of key management in the “one time pad” encryption system. The experimental results and security analysis show that the algorithm has some advantages of large key space, no obvious statistical characteristics of ciphertext, sensitivity to plaintext and key and able to resist differential attacks and chosen plaintext attack. It has good application prospects.

Security of image communication is more and more important in many applications such as the transmission of military and medical images. To meet the requirement, a new color image encryption algorithm using a new one-dimension (1D) chaotic map was proposed recently, which can resist various attacks because the range of the new chaotic map is larger than that of the previous ones. In our study, the security of the new original method is analyzed and a novel attack method is proposed. It is demonstrated that the scheme is not secure under chosen-plaintext attack, by which the encrypted image can be successfully converted into the corresponding plaintext image without any error.

In order to meet the requirement of secure image communication in a resource-constrained network environment, a novel lightweight chaotic image encryption scheme based on permutation and diffusion has been proposed. It was claimed that this scheme can resist differential attacks, statistical attacks, etc. However, the original encryption scheme is found to be vulnerable and insecure to chosen-plaintext attack (CPA). In this paper, the original encryption scheme is analyzed comprehensively and attacked successfully. Only by choosing a full zero image as the chosen-plaintext of the diffusion phase, the encrypted image can be restored into permutation-only phase, and by applying the other chosen images as the chosen-plaintexts of the permutation phase, the map matrix which is equivalent to the secret key of the permutation phase can be further revealed. Experiments and analysis verify the feasibility of our proposed attack strategy. [ABSTRACT FROM AUTHOR]

This paper introduces a six-dimensional discrete chaotic systems (SDDCS) with some simple sine functions and a chaotic pseudorandom number generator (CPRNG) that is designed based on the SDDCS. A encryption scheme with both key avalanche effect and plaintext avalanche effect (SESKPAE) is proposed by using the random sequence generated by the CPRNG. The algorithm has three advantages: First, the initial values of the chaotic system are calculated by using the SHA-256 hash value of the plain image and the given values, there are different initial values for different plain images. Thus, our algorithm can resist against the chosen-plaintext and known-plaintext attacks effectively. Second, the new algorithm adopts ciphertext feedback mechanism to further strengthen the safety. Third, our new algorithm has an “avalanche effect”, in other words, the decrypted ciphertext will become a “white” image with a few “black spots” rather than a random chaotic image as a result of the wrong key. The experimental results and security analysis show that the algorithm has the advantages of large key space, no obvious statistical characteristics of ciphertext, sensitive to plaintext and keys, and able to resist chosen-plaintext attack and active attacks. [ABSTRACT FROM AUTHOR]

Data outsourcing service can shift the local data storage and maintenance to cloud service provider (CSP) to ease the burden from data owner, but it brings the data security threats as CSP is always considered to honest-but-curious. Therefore, searchable encryption (SE) technique which allows cloud clients (including data owner and data user) to securely search over ciphertext through keywords and selectively retrieve files of interest is of prime importance. However, in practice, data user’s access permission always dynamically varies with data owner’s preferences. Moreover, existing SE schemes which are based on attribute-based encryption (ABE) incur heavy computational burden through attribution revocation and policy updating. To allow data owner to flexibly grant access permissions, we design a secure cryptographic primitive called as efficient data owner authorized search over encrypted data scheme through utilizing identity-based encryption (IBE) technique. The formal security analysis proves that our scheme is secure against chosen-plaintext attack (CPA) and chosen-keyword attack (CKA) without random oracle. Besides, empirical experiments over real-world dataset show that our scheme is efficient and feasible with regard to data access control. [ABSTRACT FROM AUTHOR]