Security Of Cipher Research Articles

Improved Perceptual Video Encryption Technique using Residue Number System

In this paper, we propose an enhanced perceptual video encryption technique to speed-up and secure cipher video transmitted across networks using Residue Number System (RNS). The technique proposes a new reverse converter with smaller dynamic range using the moduli set {2n-1, 2n, 2n+1} that is integrated into our previous work of [2]. After encryption, cipher video is encoded into three residual videos that have smaller pixel values and ideal for transmission across networks. Instead of transmitting the three (3) residual videos, the technique effectively transmits and decodes only two (2) of them back into the original video with same visual quality. Experimental results show that the technique enhances transmission speed and security of cipher video across networks.

On the extension and security of key schedule of GOST

A type of simple key schedule especially suitable for lightweight block ciphers is defined as straightforward key schedule in this study. As a typical example, GOST-type key schedule, which is an extension of the key schedules of Russian Standard GOST and its newly modified version GOST2, is introduced and classified. GOST2 is designed based on the GOST encryption structure with different but the same type of key schedule to overcome the weakness of GOST against self-similarity properties-based attacks. However, it has been shown in Fast Software Encryption 2017, the simple change in the key schedule is insufficient to offer 256-bit security. By constructing an evaluation framework combining self-similarity properties and meet-in-the-middle attack, properties of GOST-type key schedules are evaluated, and candidate key schedules are provided in this work. These candidate key schedules are able to provide much better security for GOST and GOST2 ciphers than their original key schedules, and the pre-existing self-similarity properties-based attacks of full round GOST and GOST2 can be avoided. The designers of GOST and GOST2 should have been more cautious choosing the parameters of key schedules. The evaluation framework proposed can be used for reference in the design of other Feistel ciphers with straightforward key schedules.

Variation and security enhancement of block ciphers by embedding

This paper proposes a method of embedding block cipher algorithms in a new algorithm in order to create variations and improving security of the original algorithm. The method is concretely explained for embedding AES128 block cipher. In practice there is often a need to develop a bank of secure cipher algorithms in short time. Designing such algorithms from first principles is a very long drawn process. The embedding method allows creating a family of ciphers which have an upgraded level of security over a chosen original algorithm and have the same key length with an option to extend the key length. The embedding method is chosen such that the efficiency of operation of the new algorithm is kept close to that of the original algorithm.

A Method to Bound the Number of Active S-Boxes for a Kind of AES-Like Structure

AbstractDue to the strong security and high performance of the AES block cipher, many hash functions take AES-like structures as building blocks. To evaluate the security of these AES-like structures against differential cryptanalysis, giving the lower bounds on the number of active S-boxes in a differential trail, is an important perspective. However, the original ‘wide-trail strategy’ for AES becomes less effective to get tight bounds for these AES-like structures, because of the different state dimensions (M×M2, instead of M×M) and different round functions from AES. In this paper, we focus on a kind of AES-like structure with state dimensions M×M2, diffusion-optimal permutations and MixColumns transformations using MDS matrices. Inspired by the ‘wide-trail strategy’, we propose a theoretical method to count active S-boxes, by which we prove that there are at least rBd(Bd−1) active S-boxes in any 2r(r≥3) rounds of such an AES-like structure, where Bd is the differential branch number of the MixColumns transformation and equals to M+1. What’s more, this lower bound can be achieved by some diffusion layers. As examples, we apply our method to the LANE hash function and 3D block cipher, optimal lower bounds are both got.

Cryptanalysis of Round-Reduced Fantomas, Robin and iSCREAM

In this work, we focus on LS-design ciphers Fantomas, Robin, and iSCREAM. LS-designs are a family of bitslice ciphers aimed at efficient masked implementations against side-channel analysis. We have analyzed Fantomas and Robin with a technique that previously has not been applied to both algorithms or linear cryptanalysis. The idea behind linear cryptanalysis is to build a linear characteristic that describes the relation between plaintext and ciphertext bits. Such a relationship should hold with probability 0.5 (bias is zero) for a secure cipher. Therefore, we try to find a linear characteristic between plaintext and ciphertext where bias is not equal to zero. This non-random behavior of cipher could be converted to some key-recovery attack. For Fantomas and Robin, we find 5 and 7-round linear characteristics. Using these characteristics, we attack both the ciphers with reduced rounds and recover the key for the same number of rounds. We also apply linear cryptanalysis to the famous CAESAR candidate iSCREAM and the closely related LS-design Robin. For iScream, we apply linear cryptanalysis to the round-reduced cipher and find a 7-round best linear characteristics. Based on those linear characteristics we extend the path in the related-key scenario for a higher number of rounds.

Type-preserving matrices and security of block ciphers

We introduce a new property for mixing layers which guarantees protection against algebraic attacks based on the imprimitivity of the group generated by the round functions. Mixing layers satisfying this property are called non-type-preserving. Our main result is to characterize such mixing layers by providing a list of necessary and sufficient conditions on the structure of their underlying binary matrices. Then we show how several families of linear maps are non-type-preserving, including the mixing layers of AES, GOST and PRESENT. Finally we prove that the group generated by the round functions of an SPN cipher with addition modulo \begin{document}$ 2^n $\end{document} as key mixing function is primitive if its mixing layer satisfies this property.

Effects of Limited Computational Precision on the Discrete Chaotic Sequences and the Design of Related Solutions

In this paper, we analyzed the periodicity of discrete Logistic and Tent sequences with different computational precision in detail. Further, we found that the process of iterations of the Logistic and Tent mapping is composed of transient and periodic stages. Surprisingly, for the different initial iterative values, we first discovered that all periodic stages have the same periodic limit cycles. This phenomenon has seriously affected the security of chaotic cipher. To solve this problem, we designed a novel discrete chaotic sequence generator based on m‐sequence and discrete chaotic mapping. The experimental results indicated that the chaotic sequence generator can generate pseudorandom chaotic sequences with large periodicity and good performance under the condition of limited computational precision.

Modified Hill Cipher Secure Technique using Latin Square and Magic Square

Modified Hill Cipher Secure Technique using Latin Square and Magic Square

Collusion-Resistant Processing of SQL Range Predicates

Prior solutions for securely handling SQL range predicates in outsourced Cloud-resident databases have primarily focused on passive attacks in the Honest-but-Curious adversarial model, where the server is only permitted to observe the encrypted query processing. We consider here a significantly more powerful adversary, wherein the server can launch an active attack by clandestinely issuing specific range queries via collusion with a few compromised clients. The security requirement in this environment is that data values from a plaintext domain of size N should not be leaked to within an interval of size H. Unfortunately, all prior encryption schemes for range predicate evaluation are easily breached with only O(log _2psi ) range queries, where psi = N{/}H. To address this lacuna, we present SPLIT, a new encryption scheme where the adversary requires exponentially more—{mathbf{O}}(psi )—range queries to breach the interval constraint and can therefore be easily detected by standard auditing mechanisms. The novel aspect of SPLIT is that each value appearing in a range-sensitive column is first segmented into two parts. These segmented parts are then independently encrypted using a layered composition of a secure block cipher with the order-preserving encryption and prefix-preserving encryption schemes, and the resulting ciphertexts are stored in separate tables. At query processing time, range predicates are rewritten into an equivalent set of table-specific sub-range predicates, and the disjoint union of their results forms the query answer. A detailed evaluation of SPLIT on benchmark database queries indicates that its execution times are well within a factor of two of the corresponding plaintext times, testifying its efficiency in resisting active adversaries.

Efficient and secure cipher scheme for multimedia contents

The impact of confidentiality and privacy breaches are more pronounced when dealing with multimedia contents. One of the obvious techniques to counter these threats is the use of encryption. A number of algorithms for robust image encryption, targeted for real-time applications with tight resource constraints, has been proposed in the literature. In this paper, first, we analyze two recent cipher schemes for image contents, which are based on two rounds. We show that the schemes are designed to ensure maximum avalanche effect in the whole image by employing the chaining block code mode (CBC) in forward and backward directions. However, they do not lend themselves to parallel implementation and they have a problem with error propagation, which is not desirable for wireless multimedia transmission. As such, we propose to redesign the underlying algorithm to make it practical when used with applications that either suffer from a high error percentage or from real-time constraints. The modified cipher employs the counter mode to eliminate the chaining process (forward and backward), which allows for parallel computations and minimizes the effect of error propagation. According to the security and performance results, the proposed scheme can respond better to the applications and/or system requirements and limitations by ensuring a better performance and an equally high level of security compared to both ciphers in addition to minimum error propagation. To the best of our knowledge, the proposed scheme is the first dynamic key-dependent stream cipher scheme with a pseudo-random key-stream generation for re-ordering of sub-matrices.

A new Color image Encryption based on multi Chaotic Maps

This paper presents a new RGB image encryption scheme using multi chaotic maps. Encrypting an image is performed via chaotic maps to confirm the properties of secure cipher namely confusion and diffusion are satisfied. Also, the key sequence for encrypting an image is generated using a combination of 1D logistic and Sine chaotic maps. Experimental results and the compassion results indicate that the suggested scheme provides high security against several types of attack, large secret keyspace and highly sensitive.

Double-block Hash-then-Sum: A Paradigm for Constructing BBB Secure PRF

SUM-ECBC (Yasuda, CT-RSA 2010) is the first beyond birthday bound (BBB) secure block cipher based deterministic MAC. After this work, some more BBB secure deterministic MACs have been proposed, namely PMAC_Plus (Yasuda, CRYPTO 2011), 3kf9 (Zhang et al., ASIACRYPT 2012) and LightMAC_Plus (Naito, ASIACRYPT 2017). In this paper, we have abstracted out the inherent design principle of all these BBB secure MACs and present a generic design paradigm to construct a BBB secure pseudo random function, namely Double-block Hash-then- Sum or in short (DbHtS). A DbHtS construction, as the name implies, computes a double block hash on the message and then sum the encrypted output of the two hash blocks. Our result renders that if the underlying hash function meets certain security requirements (namely cover-free and block-wise universal advantage is low), DbHtS construction provides 2n/3-bit security. We demonstrate the applicability of our result by instantiating all the existing beyond birthday secure deterministic MACs (e.g., SUM-ECBC, PMAC_Plus, 3kf9, LightMAC_Plus) as well as a simple two-keyed variant for each of them and some algebraic hash based constructions.

Observations on the truncated differential of SP block ciphers and their applications to mCrypton and CRYPTON V1.0

Truncated differential attack (TDA) proposed by Knudsen in Fast Software Encryption 1995 (FSE'95) has been widely used in the analysis of block ciphers. In this study, the authors specifically study the security of SP block ciphers against TDA. In FSE'15, Li et al. introduced a meet-in-the-middle technique to construct truncated differential for Feistel ciphers. They first apply Li's technique to SP block ciphers and get some further results. Second, they introduce the concept of generalised truncated difference to control the diffusion of active S-boxes in the truncated differential. On the basis of these, two 5-round truncated differential distinguishers for mCrypton and CRYPTON V1.0 have been constructed. Using these two 5-round distinguishers, they present the first 8-round DA on mCrypton-64 and improve the former best TDA on CRYPTON V1.0 by one round.

A dynamic approach for a lightweight and secure cipher for medical images

Protecting the contents of medical records is of paramount importance when it comes to preserving patients’ privacy. Most existing cryptographic-based solutions rely on traditional encryption algorithms having a multi-round structure, which introduces processing latency and requires increased resources. Medical images possess special characteristics compared to other types of images. The main goal of this paper is to leverage these characteristics to design and implement an efficient and secure encryption algorithm for such images. The proposed solution defines three variants of encryption algorithms: (a) full, (b) middle-full, and (c) selective. The full approach encrypts all sub-matrices of an image, while the middle-full variant is a middle solution between the selective and full algorithms and its goal is to just hide the type of the medical image. Selective encryption identifies a set of sub-matrices of an image according to a statistical average test, known as region of interest (ROI). In the three approaches, a high security level is ensured since each image is encrypted independently of the previous and next images. Also, all primitives of the proposed cipher, such as permutation and substitution, depend on a dynamic key. Furthermore, the encryption scheme is efficient since the proposed round function is lightweight and applied for only one round. This reduces the latency and the required resources as compared to traditional cryptographic schemes. The proposed approach is flexible as it can be applied in either selective, middle-full, or full mode. Also, the size of a sub-matrix is variable and can be changed according to the available memory size. Several security and performance tests are conducted to evaluate the effectiveness of the proposed solution. The results validate the robustness of the proposed scheme against almost all considered types of attacks and show an improvement in terms of latency and resources compared to current image-encryption schemes. Also, the results confirm the robustness of the proposed algorithm in protecting the contents of medical images.

Cryptanalysis and improvement in an image encryption scheme using combination of the 1D chaotic map

In this paper, we evaluate the security of an image cipher recently proposed. Three different cryptographic primitives, i.e., permutation, diffusion, and cyclic rotation, were integrated in this cipher so as to obtain a satisfactory security performance within a single encryption round. It is found that the equivalent key stream elements can be derived under chosen-plaintext attack. Both mathematical proof and experimental validation are given in detail. Concerning the presented analysis and some common defects of chaos-based image ciphers, an enhanced image cryptosystem based on the single-round permutation–diffusion structure is further developed. Natural and medical images are introduced for experimental verification and performance comparison. The results demonstrate the security superiority of the improved cryptosystem.

Trade-off of security and performance of lightweight block ciphers in Industrial Wireless Sensor Networks

Lightweight block ciphers play an indispensable role for the security in the context of pervasive computing. However, the performance of resource-constrained devices can be affected dynamically by the selection of suitable cryptalgorithms, especially for the devices in the resource-constrained devices and/or wireless networks. Thus, in this paper, we study the trade-off between security and performance of several recent top performing lightweight block ciphers for the demand of resource-constrained Industrial Wireless Sensor Networks. Then, the software performance evaluation about these ciphers has been carried out in terms of memory occupation, cycles per byte, throughput, and a relative good comprehensive metric. Moreover, the results of avalanche effect, which shows the possibility to resist possible types of different attacks, are presented subsequently. Our results show that SPECK is the software-oriented lightweight cipher which achieves the best performance in various aspects, and it enjoys a healthy security margin at the same time. Furthermore, PRESENT, which is usually used as a benchmark for newer hardware-oriented lightweight ciphers, shows that the software performance combined with avalanche effect is inadequate when it is implemented. In the real application, there is a need to better understand the resources of dedicated platforms and security requirement, as well as the emphasis and focus. Therefore, this case study can serve as a good reference for the better selection of trade-off between performance and security in constrained environments.

On stream ciphers with provable beyond-the-birthday-bound security against time-memory-data tradeoff attacks

Most stream ciphers are vulnerable against generic time-memory-data tradeoff (TMD-TO) attacks, which reduce their effective key length to the birthday bound $n/2$ , where n denotes the inner state length of the underlying keystream generator. This implies the necessity of a comparatively large inner state length for practical stream ciphers (e.g., $n = 288$ and $n = 160$ for the eSTREAM portfolio members Trivium and Grain v1, respectively). In this paper, we propose and analyze the Lizard-construction, a new way to build stream ciphers. We prove a tight $2n/3$ bound on its security against TMD-TO key recovery attacks, where the security lower bound refers to chosen-IV attacks. The security against TMD-TO distinguishing attacks remains at the birthday-bound level $n/2$ . The lower bound refers to a random oracle model which allows to derive formal security results w.r.t. generic TMD-TO attacks. While similar frameworks have already been widely used for analyzing the security of block cipher, MAC, and hash function constructions, to the best of our knowledge this is the first time that such a model is considered in the context of stream ciphers. The security analysis presented in this paper is also of immediate practical relevance as, with the stream cipher Lizard, a first instantiation of our new design principle (which we hence named Lizard-construction) was introduced at FSE 2017. Lizard has an inner state length of only 121 bits and surpasses Grain v1, the most hardware efficient member of the eSTREAM portfolio, in important metrics for lightweight ciphers such as chip area and power consumption.

ABC Optimization Based Construction of Strong Substitution-Boxes

Most of the block ciphers contain substitution-boxes as their cornerstone primitive to add requisite nonlinearity. S-boxes are responsible to ensure strong confusion and resistance to linear and differential assaults. The security of such ciphers relies on the strength of S-boxes deployed during substitution stage. It is challenging to construct cryptographically strong S-boxes that satisfy several properties such as high nonlinearity, good avalanche effect, bit-independent criteria, low differential uniformity and linear probability, etc. In this paper, we proposed to construct an S-box based on artificial bee colony optimization and chaotic map. The algorithm is designed to optimize an initial S-box to satisfy many properties. The simulation outcomes and comparison with recent proposals show that the proposed ABC optimization based algorithm performs reasonably well and construct S-box that exhibits higher security strength.

A novel encryption scheme for high-contrast image data in the Fresnelet domain.

In this paper, a unique and more distinctive encryption algorithm is proposed. This is based on the complexity of highly nonlinear S box in Flesnelet domain. The nonlinear pattern is transformed further to enhance the confusion in the dummy data using Fresnelet technique. The security level of the encrypted image boosts using the algebra of Galois field in Fresnelet domain. At first level, the Fresnelet transform is used to propagate the given information with desired wavelength at specified distance. It decomposes given secret data into four complex subbands. These complex sub-bands are separated into two components of real subband data and imaginary subband data. At second level, the net subband data, produced at the first level, is deteriorated to non-linear diffused pattern using the unique S-box defined on the Galois field . In the diffusion process, the permuted image is substituted via dynamic algebraic S-box substitution. We prove through various analysis techniques that the proposed scheme enhances the cipher security level, extensively.

Tweaking a block cipher: multi-user beyond-birthday-bound security in the standard model

In this paper, we present a generic construction to create a secure tweakable block cipher from a secure block cipher. Our construction is very natural, requiring four calls to the underlying block cipher for each call of the tweakable block cipher. Moreover, it is provably secure in the standard model while keeping the security degradation minimal in the multi-user setting. In more details, if the underlying blockcipher E uses n-bit blocks and 2n-bit keys, then our construction is proven secure against multi-user adversaries using up to roughly $$2^n$$ time and queries as long as E is a secure block cipher.