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Worker selection in crowdsensing plays an important role in the quality control of sensing services. The majority of existing studies on worker selection {\color{red}were} largely dependent on a trusted centralized server, which might suffer from single point of failure, the lack of transparency and so on. Some works recently proposed blockchain-based crowdsensing, which {\color{red}utilized} reputation values stored on blockchains to select trusted workers. However, the transparency of blockchains enables attackers to effectively infer private information about workers by the disclosure of their reputation values. In this paper, we {\color{red}proposed} the TrustWorker, a trustworthy and privacy-preserving worker selection scheme for blockchain-based crowdsensing. By taking the advantages of blockchains such as decentralization, transparency and immutability, our TrustWorker {\color{red}could} make the worker selection process trustworthy. To protect workers' reputation privacy in our TrustWorker, we {\color{red}adopted} a deterministic encryption algorithm to encrypt reputation values and then {\color{red}selected} the top N workers in the light of secret minimum heapsort scheme. Finally, we theoretically {\color{red}analyzed} the effectiveness and efficiency of our TrustWorker, and then {\color{red}conducted} a series of experiments. The theoretical analysis and experiment results demonstrate that our TrustWorker can achieve trustworthy worker selection, while ensuring the workers' privacy and the high quality of sensing services.

An increasing demand of secure data transmission over internet leads to the challenge of implementing a consistent cryptosystem. In 2004, USA navy published the patent which highlights the importance of fractal as an encryption/decryption key in a cryptosystem [1]. Fractal possess butterfly effect i.e. sensitivity to initial condition, due to which small change in input produces a major change in output. This paper summarizes the various recent image encryption techniques in which fractal key is used to encrypt/decrypt followed by substitution, scrambling and diffusion techniques to provide strong cryptosystem. The algorithms covered both private key encryption as well as public key encryption technique in the paper. The analysed algorithms include a set of fractal function such as Mandelbrot set, Julia set, Hilbert curve, 3D fractal, multi-fractal, IFS and chaotic function to generate a complex key used in the encryption process. Corresponding performance of each algorithm is analysed by PSNR test, key space, sensitivity analysis and correlation coefficient value between the adjacent pixels of both images (Original image and encrypted image) which shows significant improvement in performance over the traditional encryption methods.

Encrypted deduplication combines encryption and deduplication to simultaneously achieve both data security and storage efficiency. State-of-the-art encrypted deduplication systems mainly build on deterministic encryption to preserve deduplication effectiveness. However, such deterministic encryption reveals the underlying frequency distribution of the original plaintext chunks. This allows an adversary to launch frequency analysis against the ciphertext chunks and infer the content of the original plaintext chunks. In this paper, we study how frequency analysis affects information leakage in encrypted deduplication storage, from both attack and defense perspectives. Specifically, we target backup workloads, and propose a new inference attack that exploits chunk locality to increase the coverage of inferred chunks. We further combine the new inference attack with the knowledge of chunk sizes and show its attack effectiveness against variable-size chunks. We conduct trace-driven evaluation on both real-world and synthetic datasets and show that our proposed attacks infer a significant fraction of plaintext chunks under backup workloads. To defend against frequency analysis, we present two defense approaches, namely MinHash encryption and scrambling. Our trace-driven evaluation shows that our combined MinHash encryption and scrambling scheme effectively mitigates the severity of the inference attacks, while maintaining high storage efficiency and incurring limited metadata access overhead., 31 pages, Accepted by ACM Transactions on Storage

In this era of big data, data transactions are becoming more frequent and bringing new benefits for both data buyers and providers. However, there are no data transaction schemes to satisfy the special security and business requirements of data transactions. In this paper, we introduce the requirements in practical data transaction processes and compare the differences of requirements and techniques between data transaction and traditional data sharing. Next, we propose and implement the first data transaction scheme based on a newly defined concept probabilistic commutative encryption, which makes the decryption order of a probabilistic encryption algorithm and a deterministic encryption algorithm commutative. Since the security concerns of both sides can be achieved in a malicious model, our scheme is fair to both data buyers and data providers from a business perspective. Furthermore, our scheme allows data transaction to be partly outsourced to a semi-honest cloud storage platform.

Multivariate Polynomial Public Key (MPPK) is a cryptographic system, over a prime Galois field. A key pair is generated using a multiplier multivariate polynomial and two multiplicand univariate solvable polynomials. They yield two product multivariate polynomials. The first variable is used for carrying the message or secret and others are used as noise sources. The public key consists of all the coefficients of the product multivariate polynomials, except the two constant coefficients, in terms with coefficients attached to the message variable, and a noise function or a polynomial of only noise variables generated from the constant term of the multiplier multivariate polynomial by multiplying a private random variable R. The private key is made of both univariate solvable multiplicand polynomials and the private R. Encryption takes a secret message and random numbers for noises, adding noise that is automatically cancelled by decryption. Decryption is achieved evaluating a solvable equation. We review security analysis that can be employed to crack MPPK secrets and private keys. Finally, we discuss indistinguishability and non-deterministic encryption, key properties of MPPK.

Securing cloud databases is a challenge in the cloud computing paradigm. Several research studies have been conducted to improve the security level in cloud computing. Many security schemes do not preserve mathematical or logical operations over encrypted data. Order Preserving Encryption schemes (OPEs) preserve the ordering (logical) operations over encrypted data. However, many OPE schemes leak information. Mutable Order Preserving Encoding (MOPE) algorithm achieves ideal security when it uses Randomized Encryption (RND) rather than Deterministic Encryption (DET) Scheme. RND and DET can be implemented with any standard cipher such as AES. This research proposes to use DET for MOPE and achieves the same security level when it uses RND. This paper proposes to change the encryption key on a certain time or a certain number of transactions. MOPE keeps its search tree balanced on each transaction applied by the system to maintain the performance. To enhance the security level without degrading the performance, this paper is utilizing the time consumed by rebalancing part of the tree in MOPE algorithm. This paper finds an optimal window to change the encryption key with an acceptable loss of performance.

With the development of cloud computing, people prefer to outsource images to cloud service for saving storage and convenient retrieval. For privacy-preserving purposes, sensitive images, such as medical and personal images, need to be encrypted before outsourcing, which causes the content-based image retrieval technology on plaintext domain unusable. In order to achieve similarity search on encrypted domain, this paper proposes reversible cellular automata image encryption for similarity search. We firstly define the similarity search on encrypted images, and analyze its feasibility when implementing pixel-based deterministic encryption. According to this, we introduce a deterministic encryption based on reversible cellular automata (DERCA). Then we put forward a two-level-granularity image encryption which supports extracting color histogram from encrypted image for similarity search, based on DERCA. The pixels in an image are encrypted in pixel-granularity or pixel-set-granularity to solve utility-security dilemma. And block-based permutation method is used to improve the image security and retrieval accuracy. Experiments on Corel-1000 demonstrate that the proposed method not only offers high image security, but also yields superior retrieval accuracy on encrypted images compared with other image encryption algorithms for similarity search.

We study how to make any deterministic encryption scheme probabilistic and secure against adaptively chosen ciphertext attacks. A new transpositional padding encryption scheme is proposed, with which we construct a universal scheme, namely, a transpositional padding encryption scheme, which has three novel attributes: 1) it can pad a given plaintext into several different values once the randomness is chosen while the previous padding schemes only pad a given plaintext into a fixed value; 2) it introduces the randomness into a ciphertext without employing hash function or random oracle, and; 3) it enables the encrypted message to contain more useful information that may exceed the upper limit of plaintext space. Then, we give this encryption scheme an instantiation of RSA, which is proven to be indistinguishable under adaptively chosen ciphertext attacks without random oracle that assumes a variant of the standard RSA problem. The variant problem is a novel arithmetic problem, and it is weaker than the standard RSA problem.

We study the encryption and decryption processes of color images using the synchronization of polarization dynamics in a free-running vertical-cavity surface-emitting laser (VCSEL). Here, we consider a bidirectional master-slave configuration or two-way coupling with two VCSELs. The latter are shown to exhibit hyperchaos and synchronization with a high level of similarity between their emission characteristics. The coupled VCSELs are then used as a transmitter and a receiver for the communication of image or data. Furthermore, we propose a modified chaos-based image encryption algorithm using the pixel- and bit-level permutations which provides robust, faster and simpler encryption/decryption compared to many other chaos-based cryptosystems. The performances of the new cryptosystem are analyzed and compared with a recently developed scheme [Opt. Las. Eng. 90 (2017) 238-246]. The security analysis and some statistical investigations show that the proposed cryptosystem is resistant to various types of attacks and is efficient for secure communications in nonlinear optical media., 13 pages, 11 figures, 7 tables

Classically, selective-opening attack (SOA) has been studied for randomized primitives, like randomized encryption schemes and commitments. The study of SOA for deterministic primitives, which presents some unique challenges, was initiated by Bellare et al. (PKC 2015), who showed negative results. Subsequently, Hoang et al. (ASIACRYPT 2016) showed positive results in the non-programmable random oracle model. Here we show the first positive results for SOA security of deterministic primitives in the standard (RO devoid) model. Our results are: Any 2t-wise independent hash function is SOA secure for an unbounded number of “t-correlated” messages, meaning any group of up to t messages are arbitrarily correlated. A construction of a deterministic encryption scheme with analogous security, combining a regular lossy trapdoor function with a 2t-wise independent hash function. The one-more-RSA problem of Bellare et al. (J. Cryptology 2003), which can be seen as a form of SOA, is hard under the \(\varPhi \)-Hiding Assumption with large enough encryption exponent.

The study of sending and receiving secret messages is called cryptography. Generally, senders and receivers are unaware about the process of encryption and decryption. Hence, encryption plays an important role in data communication and data security. The meaning of encryption is not only to keep data confidential from unwanted access but also ensuring the data integrity through available way. As the capacity of breaking the security is increasing rapidly, so, the process that hides information is one of the most concerned topics. Advanced Encryption Standard is a popular, widely used and efficient encryption algorithm, which has been used since it was invented. This paper focuses on the AES key generation process and Substitution box. It modifies the conventional key generation technique and builds the dynamic 3-Dimensional S-box of Advance Encryption Standard. The proposed approach suggests 3-Dimensioanl Key Generation Matrix and S-box. As per shown this novel technique increases the amount of time it needs during encryption and decryption. The experimental result shows that it also enhances the strength of AES algorithm. The proposed approach illustrates the theoretical analysis and corresponding experimented results., 7 pages, 14 figures, 4 tables. Published in IJCSA in 2017

International audience; Functional encryption lies at the frontiers of the current research in cryptography; some variants have been shown sufficiently powerful to yield indistinguishability obfuscation (IO), while other variants have been constructed from standard assumptions such as LWE. Indeed, most variants have been classified as belonging to either the former or the latter category. However, one mystery that has remained is the case of secret-key functional encryption with an unbounded number of keys and ciphertexts. On the one hand, this primitive is not known to imply anything outside of minicrypt, the land of secret-key cryptography, but, on the other hand, we do no know how to construct it without the heavy hammers in obfustopia. In this work, we show that (subexponentially secure) secret-key functional encryption is powerful enough to construct indistinguishability obfuscation if we additionally assume the existence of (subexponentially secure) plain public-key encryption. In other words, secret-key functional encryption provides a bridge from cryptomania to obfustopia. On the technical side, our result relies on two main components. As our first contribution, we show how to use secret-key functional encryption to get “exponentially efficient indistinguishability obfuscation” (XIO), a notion recently introduced by Lin et al. (PKC’16) as a relaxation of IO. Lin et al. show how to use XIO and the LWE assumption to build IO. As our second contribution, we improve on this result by replacing its reliance on the LWE assumption with any plain public-key encryption scheme. Lastly, we ask whether secret-key functional encryption can be used to construct public-key encryption itself and therefore take us all the way from minicrypt to obfustopia. A result of Asharov and Segev (FOCS’15) shows that this is not the case under black-box constructions, even for exponentially secure functional encryption. We show, through a non-black-box construction, that subexponentially secure-key functional encryption indeed leads to public-key encryption. The resulting public-key encryption scheme, however, is at most quasi-polynomially secure, which is insufficient to take us to obfustopia.

Recently, database users have begun to use cloud database services to outsource their databases. This is due to the high computation speed and the huge storage capacity the cloud owners provide at low prices. Despite cloud computing being an attractive environment for database users, privacy issues are cause for concern for database owners since the data access will be out of their control. Encryption is the only way of assuaging users’ fears surrounding data privacy. However, executing Structured Query Language (SQL) queries over encrypted data is a challenging task, especially if the data are encrypted by a randomized encryption algorithm. Many researchers have addressed the privacy issues by using deterministic encryption, onion layers encryption, or homomorphic encryption to encrypt data. But, even with these systems, the encrypted data can still be subject to attack. In this research, we propose a model to execute SQL queries over encrypted data, where the data are encrypted by a single randomized encryption algorithm–namely, Advanced Encryption Standard AES-CBC. We move most of the computations to the cloud and leave users with no crypto computation. Our model intends to narrow the range of retrieved encrypted records from the cloud to a small set of records that are candidates for the user’s query. We implement and evaluate our model and find that it is both practical and efficient. Our experiments show that our model succeeds in minimizing the decryption processes to less than 30% of decryption the whole set of encrypted records in a table.

Chaotic synchronization has suffered from demodulating information by hackers via the public channel. Different methods have been developed to hide the contents of a message using chaotic signals. Nevertheless, many studies have shown that most of the existing methods are unreliable in the aspect of security. According to the above, in order to enhance the strength of the cryptosystem and provide greater security, we carry out double encryption which combines chaotic synchronization with RSA algorithm. In this study, a design methodology for neural-network (NN)-based secure communications in multiple time-delay chaotic (MTDC) systems is proposed to obtain double encryption via RSA algorithm and chaotic synchronization. RSA algorithm is an asymmetric encryption and its strength is based on the tremendous difficulty of factorizing two large prime numbers. Accordingly, it takes much more time to process RSA algorithm if the length of the key is much longer. A shorter key is used to decrease the processing time of RSA algorithm in this work. Nevertheless, it will result in a lower security of the cryptosystem. In order to enhance the strength of the cryptosystem, we carry out double encryption which combines chaotic synchronization with RSA algorithm. Moreover, an IGA is proposed in this study to effectively overcome the weakness of the traditional GA. On the basis of the IGA, a fuzzy controller is synthesized to not only realize the exponential synchronization, but also achieve optimal H ∞ performance by minimizing the disturbances attenuation level. Finally, a numerical example with simulations is given to illustrate the effectiveness of our approach.

Image encryption is rapidly increased recently by the increasing use of the internet and communication media. Sharing important images over unsecured channels is liable for attacking and stealing. Encryption techniques are the suitable methods to protect images from attacks. Hill cipher algorithm is one of the symmetric techniques, it has a simple structure and fast computations, but weak security because sender and receiver need to use and share the same private key within a non-secure channels. A new image encryption technique that combines Elliptic Curve Cryptosystem with Hill Cipher (ECCHC) has been proposed in this paper to convert Hill cipher from symmetric technique to asymmetric one and increase its security and efficiency and resist the hackers. Self-invertible key matrix is used to generate encryption and decryption secret key. So, no need to find the inverse key matrix in the decryption process. A secret key matrix with dimensions 4 × 4 will be used as an example in this study. Entropy, Peak Signal to Noise Ratio (PSNR), and Unified Average Changing Intensity (UACI) will be used to assess the grayscale image encryption efficiency and compare the encrypted image with the original image to evaluate the performance of the proposed encryption technique. Keywords: Elliptic Curve Cryptography, Hill cipher, Self-invertible, Entropy, Peak Signal to Noise Ratio, Unified Average Changing Intensity

In order to resolve the key escrow in identity-based scheme and the significant cost of using a PKI system in traditional public key scheme, the notion of certificateless public key cryptography (CL-PKC) was introduced. The first certificateless public key encryption scheme (CL-PKE) was proposed by Al-Riyami and Paterson, and then further schemes were developed. However, most of them are constructed from the bilinear pairing which is a time costing operation. In this paper, we construct an efficient CL-PKE scheme from RSA since RSA is the de facto Internet standard and is widely used in many applications. The security is based on Kilian–Petrank’s RSA assumption which is a variant of RSA.

In this paper, by using Logistic, Sine and Tent systems we define a combination chaotic system. Some properties of the chaotic system are studied by using figures and numerical results. A color image encryption algorithm is introduced based on new chaotic system. Also this encryption algorithm can be used for gray scale or binary images. The experimental results of the encryption algorithm show that the encryption algorithm is secure and practical.

Bellare, Boldyreva, and O’Neill (CRYPTO ’07) initiated the study of deterministic public-key encryption as an alternative in scenarios where randomized encryption has inherent drawbacks. The resulting line of research has so far guaranteed security only for adversarially-chosen plaintext distributions that are independent of the public key used by the scheme. In most scenarios, however, it is typically not realistic to assume that adversaries do not take the public key into account when attacking a scheme.

In this paper, enhancement of an existing optical simultaneous fusion, compression and encryption (SFCE) scheme in terms of real-time requirements, bandwidth occupation and encryption robustness is proposed. We have used and approximate form of the DCT to decrease the computational resources. Then, a novel chaos-based encryption algorithm is introduced in order to achieve the confusion and diffusion effects. In the confusion phase, Henon map is used for row and column permutations, where the initial condition is related to the original image. Furthermore, the Skew Tent map is employed to generate another random matrix in order to carry out pixel scrambling. Finally, an adaptation of a classical diffusion process scheme is employed to strengthen security of the cryptosystem against statistical, differential, and chosen plaintext attacks. Analyses of key space, histogram, adjacent pixel correlation, sensitivity, and encryption speed of the encryption scheme are provided, and favorably compared to those of the existing crypto-compression system. The proposed method has been found to be digital/optical implementation-friendly which facilitates the integration of the crypto-compression system on a very broad range of scenarios.

Database encryption is essential for cloud database systems. For a large database, decryption could take a lot of computational time. Therefore, verifying an encryption that contains a correct plaintext without decryption becomes significant for a large database system. Plaintext-checkable encryption (PCE) is a potential tool for such database systems, which is first proposed by Canard et al. in CT-RSA 2012. Although the generic PCE in the random oracle model has been studied intensively, the generic PCE in the standard model and its efficient implementation are still challenging problems. This paper presents the first generic PCE in the standard model using smooth projective hash function (SPHF) and prove its s-priv1-cca security, which is independent of current unlink security. Based on the instantiated SPHF from DDH assumption, we obtain the most efficient PCE in the standard model, without any pairing operation. Finally, we improve two existing generic constructions in the random oracle model so that they are secure under chosen ciphertext attack.

Generally, most image encryption algorithms transform original images into texture-like or noise-like ones. Unfortunately the feature like texture or noise is just a hint of the existence of encryption for attackers. To solve this problem, Bao et al. [Inf. Sci. 324(2015)197-207] proposed a new image encryption algorithm which can transform original images into visually meaningful ones. However, the resulting cipher images have some texture features which may be a hint of the existence of encryption to some extent. To overcome this flaw, we present a new visually meaningful image encryption algorithm based on discrete wavelet transform and discrete quantum walks. Numerical simulation, security analysis and performance comparison demonstrate that our proposal is superior to Bao et al.’s scheme. It promotes the combination of image encryption and quantum computation.

In this paper, a new two-dimensional Logistic ICMIC cascade map (2D-LICM) is proposed based on cascade modulation couple (CMC) model. Performance evaluations show that it has hyperchaotic behavior, wide chaotic range and large complexity. Based on this map, a novel image encryption algorithm is designed by employing bit-level permutation and diffusion simultaneously. The bit-level permutation is performed by circular shifting, and the bit-level diffusion is carried out by exclusive or ( xor ) and reverse operations. In addition, the initial values of chaotic system are updated in real time according to the obtained ciphertext and it greatly improves the ability of resisting known plaintext attack and chosen plaintext attack. Simulation results and performance analysis show that this algorithm has good encryption effect and high efficiency. It can resist typical attacks including statistical, brute-force, differential attacks and so forth.

In this paper, the problem on a memristor-based chaotic system and its application in image encryption is discussed. A new memristive chaotic system is presented, corresponding dynamical behaviors are analyzed. Then encryption method based on the new memristive chaotic system is proposed to achieve the image encryption, Finally encrypted image analysis is carried out to demonstrate the effectiveness of the image encryption method.

This paper presents a solution for secure and efficient image encryption with the help of self-adaptive permutation–diffusion and DNA random encoding. The plain image is firstly converted to DNA sequence using random encoding rules, so as to disarrange the bit distribution of the plaintext. A self-adaptive permutation–diffusion procedure is subsequently introduced for further encryption. The quantization processes of the permutation and diffusion procedures are disturbed by the intrinsic features of the plaintext, with the introduced disturbances can be automatically retrieved in the decryption end. The security of the system originates from the plaintext-related quantization of the encryption process which makes the cryptosystem secure against plaintext attack. Besides, the reusability of the random variables can dramatically promote the efficiency of the cryptosystem, which renders great potential for real-time secure image applications.

Image encryption techniques aims to protect the content of image with higher efficiency and security than conventional cryptographic methods by making use of special properties of image. This paper presents an image encryption model based on two-dimensional partitioned cellular automaton. The model has the same topology as a digital image and is flexible to images with different color depth; it is efficient as only substitution and permutation operations are involved; the properties of cellular automata make the model easy for Very Large Scale Integration (VLSI) implementation. Moreover, unlike most known image encryption algorithms, this model can support parallel computing. A probability cellular automaton called coloring model, is proposed to study the sensitivity of the encryption model. It shows that the model meets the global strict avalanche criterion in at most M + N + 7 rounds of encryption for an M × N image. Several approaches are proposed to estimate the minimal number of rounds to fulfill the global strict avalanche criterion; simulation shows that the maximal error is only one round. An image encryption algorithm based on this model is presented, which is demonstrated by experiments to own the properties of randomness and sensitivity.

Cloud and remote storage, which has become the preferred method for reducing the security risk and safeguarding our data, is widely used for backups or outsourcing. Thus, for effective utilization of data, it is desirable to perform keyword queries directly over the encrypted data. In the single-data owner architecture, it is common to use symmetric encryption cryptography and allows only the holder who has the secret key to create searchable ciphertexts and trapdoors. In the multi-data owner (MDO) architecture, the scheme uses asymmetric encryption cryptography and allows anyone to create searchable ciphertexts under the public key, while the corresponding private key creates the trapdoors. In the real world, the data come from different providers. Thus, the MDO architecture may meet more applications. However, the existing solutions, in the MDO architecture, do not guarantee security for the trapdoors and provide only linear time search. In this paper, we present a comprehensive study of searching over encrypted data in the MDO architecture, and we propose a novel scheme that supports the inverted index structure, complex search, and dynamic update. After extensive analysis and several experiments, the results indicate that our proposed method is both efficient and secure. We believe that this is the first work that achieves trapdoor security and logarithmic time pairing free search over encrypted data in the MDO architecture.

A novel symmetric and asymmetric hybrid optical cryptosystem is proposed based on compressive sensing combined with computer generated holography. In this method there are six encryption keys, among which two decryption phase masks are different from the two random phase masks used in the encryption process. Therefore, the encryption system has the feature of both symmetric and asymmetric cryptography. On the other hand, because computer generated holography can flexibly digitalize the encrypted information and compressive sensing can significantly reduce data volume, what is more, the final encryption image is real function by phase truncation, the method favors the storage and transmission of the encryption data. The experimental results demonstrate that the proposed encryption scheme boosts the security and has high robustness against noise and occlusion attacks.

As there is rapid revolution in digital multimedia which is in compressed encrypted format, the ability for creating similar and unauthorized data, that can be easily copied, manipulated and distributed has been increased. Hence for copyright management protection, ownership identification, tamper detection and for other security issues watermarking has to be carried out for tamper proofing, quality assessment and copy control for those media content. Thus there is a need for an encryption scheme which could provide security as well as allow us to watermarking these compressed encrypted data. For encryption we propose a stream cipher called Modified Rivest Cipher 4 that overcome several weaknesses of the RC4. The embedding capacity, robustness, perceptual quality and security of the proposed algorithm, using the watermarking schemes: spread spectrum, scalar costa scheme quantization index modulation has been proposed and the comparison based on PSNR, MSE and BER values has been done between various encryption algorithms.

Public key encryption with equality test (PKE-ET) is a public key encryption with an extra functionality, so-called ‘equality test’. An authorized third party can verify the equivalence between two ciphertexts encrypted under different public keys, while the decryption keeps unavailable. However, the privacy of most existing PKE-ET schemes drop to one-way security owing to the ‘equality test’ functionality. In this work, we propose a novel architecture called filtered equality test (FET), which ‘filtered’ denotes only few receiver-selected messages can be equality tested. In such model, we propose an equality test scheme, PKE-FET, which is the first one to be proved (somewhat) semantic secure. The concrete PKE-FET scheme and its rigorous security proof in the standard model are proposed. Furthermore, FET is also applied to construct a searchable encryption named PE-MKS, which is inherently proved semantic secure (so called the indistinguishability against chosen keyword attacks) in the standard model.

The paper proposes a secure audio cryptosystem that realize integrity, authentication and confidentiality. The proposed audio cryptosystem achieves integrity by applying a message digest algorithm, authentication by employing LSB watermarking and confidentiality through encryption with Advanced Encryption Standard (AES) or RC6. The main concept of the proposed audio cryptosystem relays on XORing the plain-audio with one selected image from a private image database. Then, the mixed plain-audio blocks are LSB watermarked with the selected image hash value prior to ciphering. The proposed audio cryptosystem is prepared with the potential of increasing immunity against brute force attacks and providing integrity, authentication and confidentiality through the selected image hash value addition using LSB embedding as an extra key. Also, the extra XORing step removes residual intelligibility from the plain-audio blocks, fills the speechless intervals of audio conversation and helps in destroying format and pitch information. The proposed audio cryptosystem is compared with audio encryption using AES, and RC6 through encryption key performance indicators. The comparison outcomes ensured the superiority of the proposed audio cryptosystem. Security investigation of the proposed audio cryptosystem is studied from a precise cryptographic standpoint and tests ensured the superiority of the proposed audio cryptosystem from a cryptographic standpoint.

Elliptic curve analogue ElGamal encryption scheme requires encoding of the plain message onto elliptic curve coordinate using Koblitz encoding technique before encryption operation. The paper proposes a medical image encryption scheme using improved ElGamal encryption technique. A new finding has been made in the proposed method where separate calculations for encoding plain message to elliptic curve coordinate is removed. The algorithm in the improved version of ElGamal encryption scheme is designed to encrypt medical image where data expansion issue is resolved and execution speed is enhanced. The strength of the proposed method is insured through various statistical and security analyses and comparison with other existing encryption schemes.

Cryptographic architectures provide different security properties to sensitive usage models. However, unless reliability of architectures is guaranteed, such security properties can be undermined through natural or malicious faults. In this paper, two underlying block ciphers which can be used in authenticated encryption algorithms are considered, i.e., light encryption device and high security and lightweight block ciphers. The former is of the Advanced Encryption Standard type and has been considered area-efficient, while the latter constitutes a Feistel network structure and is suitable for low-complexity and low-power embedded security applications. In this paper, we propose efficient error detection architectures including variants of recomputing with encoded operands and signature-based schemes to detect both transient and permanent faults. Authenticated encryption is applied in cryptography to provide confidentiality, integrity, and authenticity simultaneously to the message sent in a communication channel. In this paper, we show that the proposed schemes are applicable to the case study of simple lightweight CFB for providing authenticated encryption with associated data. The error simulations are performed using Xilinx Integrated Synthesis Environment tool and the results are benchmarked for the Xilinx FPGA family Virtex-7 to assess the reliability capability and efficiency of the proposed architectures.

A robust encryption algorithm using DNA and chaotic logistic maps was recently proposed, which can resist exhaustive attack, statistical attack and differential attack. The security of this encryption algorithm depends on the initial conditions of 1D and 2D logistic chaotic maps, which include the front and latter pixel sum of plain image. However, this scheme is not secure enough because the front half and latter half pixel sum can be known to the attacker. According to this security weakness the encryption algorithm is completely cracked by a novel chosen-plaintext attack scheme. Experiments and analysis verify our approach.

Over the past two decades, chaos-based encryption appeared as an original application for nonlinear dynamics and deterministic chaos to encrypt and decrypt data. In this paper, an implementation of digital image encryption scheme based on the Lorenz chaotic system is proposed. While in the process of generating chaotic key stream, the hash value of the plain image is embedded in the proposed cryptosystem to dynamically alter the initial secret keys to increase the security level. The proposed digital image encryption algorithm is described in detail along with its security analysis and implementation. The experimental results show that the proposed digital image encryption algorithm is efficient and has high security features and is suitable for practical uses across insecure networks.

Over the past decade, big data analysis has seen an exponential growth and will certainly continue to witness spectacular developments due to the emergence of new interactive multimedia applications and highly integrated systems driven by the rapid growth in information services and microelectronic devices. Up to yet, large no. of the existing mobile systems is mainly targeted to voice communications with low transmission rates. Big-Data has always been a part of our lives knowingly or unknowingly. This is a review on accessible big-data systems that include a set of tools and technique to load, extract, and improve dissimilar data while leveraging the immensely parallel processing power to perform complex transformations and analysis. Big-Data” technology faces a list of technical challenges.

Recently, a feedback image encryption algorithm with compound chaotic stream cipher based on perturbation was proposed. This paper analyzes security of the algorithm and reports that there exist some security defects, i.e., encryption of a pixel is independent on the position scrambling and the encryption round is controlled by the users. Based on them, a chosen-ciphertext attack is proposed to obtain the equivalent version of the secret key of the algorithm with $$n\cdot \lceil \log _{256} MN +2 \rceil $$ chosen cipher-images, where $$M\times N$$ is the size of the corresponding plain-images and n is the round number of encryption.

Efficient searching on encrypted data outsourced to the cloud remains a research challenge. Identity-based encryption with equality test (IBEET) scheme has recently been identified as a viable solution, in which users can delegate a trapdoor to the server and the server then searches on user outsourced encrypted data to determine whether two different ciphertexts are encryptions of the same plaintext. Such schemes are, unfortunately, inefficient particularly for deployment on mobile devices (with limited power/battery life and computing capacity). In this paper, we propose an efficient IBEET scheme with bilinear pairing, which reduces the need for time-consuming HashToPoint function. We then prove the security of our scheme for one-way secure against chosen identity and chosen ciphertext attacks (OWIDCCA) in the random oracle model (ROM). The performance evaluation of our scheme demonstrates that in comparison to the scheme of Ma (2016), our scheme achieves a reduction of 36.7% and 39.24% in computation cost during the encryption phase and test phase, respectively, and that our scheme is suitable for (mobile) cloud deployment. We propose an identity-based encryption with equality test (IBEET) scheme using bilinear pairing for cloud storage.We show that our proposed concrete scheme is provably secure. It satisfies required security properties.Detailed performance analysis and experimental result are given.

More and more sensitive information is transmitted and stored in computer networks. Security has become a critical issue. As traditional cryptographic systems are now vulnerable to attacks, DNA based cryptography has been identified as a promising technology because of the vast parallelism and extraordinary information density. While a body of research has proposed the DNA based encryption algorithm, no research has provided solutions to distribute complex and long secure keys. This paper introduces a Hamming code and a block cipher mechanism to ensure secure transmission of a secure key. The research overcomes the limitation on the length of the secure key represented by DNA strands. Therefore it proves that real biological DNA strands are useful for encryption computing. To evaluate our method, we apply the block cipher mechanism to optimize a DNA-based implementation of a conventional symmetric encryption algorithm, described as “yet another encryption algorithm”. Moreover, a maximum length matching algorithm is developed to provide immunity against frequency attacks.

Multimedia is currently seen to dominate the internet network and the mobile network traffic; hence, it is seen as the largest Big data. Generally, the symmetric encryption algorithms are applied to the ‘big multimedia data’; however; these algorithms are thought as very slow. In our study, we developed and designed a resource-efficient encryption algorithm system which applies the multithreaded programming process for the encryption of the big multimedia data. This proposed system describes a multi-level encryption model which uses the Feistel Encryption Scheme, genetic algorithms and the Advanced Encryption Standard (AES). Our system has been assessed for actual medical-based big multimedia data and compared to the benchmarked encryption algorithms like the RC6, MARS, 3-DES, DES, and Blowfish with regards to the computational run time and its throughput for the encryption and decryption procedures. In addition, the multithreaded programming approach is adopted to implement the proposed encryption system in order to enhace the system effeciencey and porfermance. Furthermore, we also compared our system with its sequential version for showing its resource efficiency. Our results indicated that our system had the least run time and a higher throughput for the encryption and decryption processes in comparison to the already existing standard encryption algorithms. Also, our system could improve the computation run time by approximately 75% and its throughput was also increased by 4-times in comparison to its sequential version. For fulfilling the security objectives, our algorithm showed a better Avalanche Effect in comparison to the existing algorithms and therefore, could be included in any encryption/decryption process of a big plain multimedia data.

In recent years, researchers have been focused on the optical asymmetric cryptosystem (OACS). The encryption key and decryption key are independent, the fact of which overcomes the linearity defect of optical encryption system. So the OACS has attracted more and more researchers’ attention. We have deeply studied the existing OACS, and found that the cryptosystem is unable to realize communication in practice. In this paper, we demonstrate the shortcomings of the present OACS and propose a practical scheme. The analysis shows that this scheme meets the communication protocol of asymmetric cryptography (ACS).

Objectives: The principal objective of this paper is to develop an enhanced algorithm of cryptography through the hybridization of existing symmetric and asymmetric encryption. Methods/Analysis: The strength of several prevailing symmetric and asymmetric encryption were utilized in the proposed methodology. ElGamal’s key security based on difficulty of solving discrete logarithm, Chaos-based’s avalanche effect of using multiple keys, RSA’s security based on the difficulty of factorization of large numbers and AES’s S-Box mapping, which makes the encryption complex and unpredictable were adapted. Findings: The strength of security of the proposed hybrid algorithm is tested by the provided examples. It was found out that with the use of different keys in encryption, various ciphertexts were generated. The published public keys using such algorithm also make it infeasible to intrude because of the difficulty of solving discrete logarithm with large prime numbers. Furthermore, the value of the ciphertext of the proposed method is significantly different and, in some cases, larger than that of RSA’s. Applications: With this newly enhanced hybrid algorithm of data encryption, transferring and conveying of data will be much more secured.

Public key encryption with keyword search is a useful primitive that provides searchable ciphertexts for some predefined keywords. It allows a user to send a trapdoor to a storage server, which enables the latter to locate all encrypted data containing the keyword(s) encoded in the trapdoor. To remove the requirement of a secure channel between the server and the receiver in identity-based encryption with keyword search, Wu et al. proposed a designated server identity-based encryption scheme with keyword search. However, our cryptanalysis indicates that Wu et al.’s scheme fails in achieving the ciphertext indistinguishability. To overcome the security weakness in the scheme and offer the multiple-keyword search function, we put forward a designated server identity-based encryption scheme with conjunctive keyword search. In the random oracle model, we formally prove that the proposed scheme satisfies the ciphertext indistinguishability, the trapdoor indistinguishability and the off-line keyword-guessing attack security. Comparison analysis shows that it is efficient and practical.