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As cloud computing becomes prevalent, more and more data owners are likely to outsource their data to a cloud server. However, to ensure privacy, the data should be encrypted before outsourcing. Symmetric searchable encryption allows users to retrieve keyword over encrypted data without decrypting the data. Many existing schemes that are based on symmetric searchable encryption only support single keyword search, conjunctive keywords search, multiple keywords search, or single phrase search. However, some schemes, i.e., static schemes, only search one phrase in a query request. In this paper, we propose a multi-phrase ranked search over encrypted cloud data, which also supports dynamic update operations, such as adding or deleting files. We used an inverted index to record the locations of keywords and to judge whether the phrase appears. This index can search for keywords efficiently. In order to rank the results and protect the privacy of relevance score, the relevance score evaluation model is used in searching process on client-side. Also, the special construction of the index makes the scheme dynamic. The data owner can update the cloud data at very little cost. Security analyses and extensive experiments were conducted to demonstrate the safety and efficiency of the proposed scheme.

Searchable encryption is an important technique for public cloud storage service to provide user data confidentiality protection and at the same time allow users performing keyword search over their encrypted data. Previous schemes only deal with exact or fuzzy keyword search to correct some spelling errors. In this paper, we propose a new wildcard searchable encryption system to support wildcard keyword queries which has several highly desirable features. First, our system allows multiple keywords search in which any queried keyword may contain zero, one or two wildcards, and a wildcard may appear in any position of a keyword and represent any number of symbols. Second, it supports simultaneous search on multiple data owner's data using only one trapdoor. Third, it provides flexible user authorization and revocation to effectively manage search and decryption privileges. Fourth, it is constructed based on homomorphic encryption rather than Bloom filter and hence completely eliminates the false probability caused by Bloom filter. Finally, it achieves a high level of privacy protection since matching results are unknown to the cloud server in the test phase. The proposed system is thoroughly analyzed and is proved secure. Extensive experimental results indicate that our system is efficient compared with other existing wildcard searchable encryption schemes in the public key setting.

© 2013 IEEE. In medical cloud computing, a patient can remotely outsource her medical data to the cloud server. In this case, only authorized doctors are allowed to access the data since the medical data is highly sensitive. Before outsourcing, the data is commonly encrypted, where the corresponding secret key is sent to authorized doctors. However, performing searches on encrypted medical data is difficult without decryption. In this paper, we propose two Secure and Efficient Dynamic Searchable Symmetric Encryption (SEDSSE) schemes over medical cloud data. First, we utilize the secure k-Nearest Neighbor (kNN) and Attribute-Based Encryption (ABE) techniques to construct a dynamic searchable symmetric encryption scheme, which can achieve forward privacy and backward privacy simultaneously. These tow security properties are vital and very challenging in the area of dynamic searchable symmetric encryption. Then, we propose an enhanced scheme to solve the key sharing problem which widely exists in the kNN based searchable encryption scheme. Compared with existing proposals, our schemes are better in terms of storage, search and updating complexity. Extensive experiments demonstrate the efficiency of our schemes on storage overhead, index building, trapdoor generating and query.

With recent studies in Searchable Symmetric Encryption (SSE), a client can efficiently perform keyword queries over its outsourced data on a remote but untrusted server (e.g., a public cloud), and correctly retrieve associated files without revealing the confidentiality of his/her data. Besides keyword search, many recent schemes also studied range queries on encrypted data, where range search is also one of the most extensively used queries in databases and information retrieval. However, most of these previous works supporting range search are neither efficient nor compatible with existing keyword SSE schemes. In this paper, we propose two range SSE schemes to enable range queries on encrypted data. Both of our schemes are not only efficient, but also highly compatible with existing keyword SSE schemes. Specifically, the search time of our first scheme is extremely efficient when the values in a range query are sparsely presenting in a dataset; while our second design can achieve an optimal token size and significantly save token generation costs. Moreover, we rigorously define and analyze the security of our schemes, and also conduct extensive experiments with a real dataset to demonstrate the performance of our schemes.

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.

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

Secure implementation of cryptographic algorithms is an important area of research. Cryptographer prefers to secure algorithms against known attacks; however designer focuses on efficient implementation. It has been established in several researches that an attack on implementation of a cipher requires far less effort than exploiting mathematical weakness of the structure. Implementation vulnerabilities are utilized by side channel attacks (SCA). In practical environment a block cipher is implemented in one of the modes of encryption like ECB, CBC, CTR. Our research focuses on finding leakage points in different modes of encryption including GCM to build hypothetical power consumption model for correlation power analysis (CPA) attack. CPA is simulated on AES-128-ECB in PIC18F4520 which yields secret key extraction in 2346 traces. Algorithmic level countermeasures for Counter mode and GCM mode are also presented. Proposed Counter and GCM mode implementation in FPGA yields 0.179% and 6.66% area overhead respectively. Authentication structure of proposed GCM is tolerant against fault injection attacks and propagates error with high probability. Single bit modifies approximately 51% bits in subsequent multiplications and disturbing the Tag by 48%. This research also highlights future recommendations for designing new resilient modes of encryption against power analysis attacks.

This paper proposed a framework which combined video data hiding method based on modifying the intra prediction mode and selective encryption method. It hides data bits by adjusting intra prediction modes while it ensures that modified prediction mode is the optimal prediction mode at the current case and hence the loss of coding performance is relatively small. The hidden bits can be some hash bits, some other key bits and other feature bits for authentication or error concealment. After that, the selective encryption is designed to support privacy protection. The experiments indicate that the proposed algorithms provide high hiding capacity, good quality of stego videos and appropriate capability of privacy protection. Moreover, the loss of PSNR, bit-rate and the delay of hiding and encryption is still acceptable.

Searchable encryption allows a cloud server to conduct keyword search over encrypted data on behalf of the data users without learning the underlying plaintexts. However, most existing searchable encryption schemes only support single or conjunctive keyword search, while a few other schemes that are able to perform expressive keyword search are computationally inefficient since they are built from bilinear pairings over the composite-order groups. In this paper, we propose an expressive public-key searchable encryption scheme in the prime-order groups, which allows keyword search policies (i.e., predicates, access structures) to be expressed in conjunctive, disjunctive or any monotonic Boolean formulas and achieves significant performance improvement over existing schemes. We formally define its security, and prove that it is selectively secure in the standard model. Also, we implement the proposed scheme using a rapid prototyping tool called Charm [37], and conduct several experiments to evaluate it performance. The results demonstrate that our scheme is much more efficient than the ones built over the composite-order groups.

Cloud storage services have become increasingly popular. Because of the importance of privacy, many cloud storage encryption schemes have been proposed to protect data from those who do not have access. All such schemes assumed that cloud storage providers are safe and cannot be hacked; however, in practice, some authorities (i.e., coercers) may force cloud storage providers to reveal user secrets or confidential data on the cloud, thus altogether circumventing storage encryption schemes. In this paper, we present our design for a new cloud storage encryption scheme that enables cloud storage providers to create convincing fake user secrets to protect user privacy. Since coercers cannot tell if obtained secrets are true or not, the cloud storage providers ensure that user privacy is still securely protected.

This paper considers the security problem of outsourcing storage from user devices to the cloud. A secure searchable encryption scheme is presented to enable searching of encrypted user data in the cloud. The scheme simultaneously supports fuzzy keyword searching and matched results ranking, which are two important factors in facilitating practical searchable encryption. A chaotic fuzzy transformation method is proposed to support secure fuzzy keyword indexing, storage and query. A secure posting list is also created to rank the matched results while maintaining the privacy and confidentiality of the user data, and saving the resources of the user mobile devices. Comprehensive tests have been performed and the experimental results show that the proposed scheme is efficient and suitable for a secure searchable cloud storage system.

We propose an encryption scheme to protect medical images using high-speed scrambling and pixel adaptive diffusion.It has a high security level as it can encrypt an identical image into different cipher-images, even when using the same secret key.We provide two implementations, which have high efficiency in hardware platforms and software platforms, respectively.The proposed encryption scheme has high security level, faster speed, and better robustness than several typical encryption schemes. This paper presents a new encryption scheme of protecting medical images. It has high efficiency and shows robustness of defending some impulse noise and data loss. First, some random data are inserted into surroundings of the image. Then, two rounds of high-speed scrambling and pixel adaptive diffusion are performed to randomly shuffle neighboring pixels and spread these inserted random data over the entire image. The proposed encryption scheme can be directly applied to medical images with any representation format. We provide two kinds of operations to implement the pixel adaptive diffusion: bitwise XOR and modulo arithmetic. The former has high efficiency in hardware platforms while the latter can achieve fast speed in software platforms. Simulations and evaluations show that both encryption schemes using bitwise XOR and modulo arithmetic have high security levels, can achieve much faster speeds, and can better adapt to impulse noise and data loss interference than several typical and state-of-the-art encryption schemes.

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.

Identity-based broadcast encryption (IBBE) is an important type of broadcast encryption. In the paper, we put forward the formal definition and security model of IBBE with leakage-resilience. Furthermore, we propose an IBBE scheme with continuous leakage-resilience. The presented scheme is resilient to private key leakage. By refreshing the private key, our scheme can resist continuous private key leakage. Based on dual system encryption technique, we prove the security of the proposed scheme under subgroup decisional assumptions. We give the specific performance analysis of leakage-resilience. The relative leakage ratio can amount to 1/3.

This paper presents the weaknesses in the cryptosystem proposed by W. Zhang and his colleagues. The proposed method to restore the permutation rule is based on the chosen-ciphertext attack. The method is successful in restoration of the permutation rule in the case of multiple encryption rounds without any knowledge about the cryptosystem. In order to improve the security of W. Zhang's cryptosystem, the proposed modifications are made to the equations to resist against the chosen-ciphertext attack. The specific examples will demonstrate the cryptanalysis and the security improvement.

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.

Lightweight devices, such as a smartcard associated with a top-box decoder in pay-TV or a SIM card coupled with a powerful (but not totally trusted) smartphone, play an important role in modern applications. The essential requirements for a cryptographic scheme to be truly implemented in lightweight devices are that it should have compact secret key size and support fast decryption. Attribute-based broadcast encryption (ABBE) combines the functionalities of both broadcast encryption and attribute-based encryption in an efficient way, ABBE is therefore a promising cryptographic scheme to be used in practical applications such as mobile pay-TV, satellite transmission, or Internet of Things. Designing an ABBE scheme which can be truly implemented in lightweight devices is still an open question. In this study, the authors solve it by proposing an efficient constant-size private key ciphertext-policy ABBE scheme for disjunctive normal form supporting fast decryption and achieving standard security levels of an ABBE scheme. They concretely show that the authors’ scheme can be truly implemented in a prototype for a smartphone-based cloud storage use case. In particular, they show how to alleviate some parts of their scheme so as to obtain a very practical system, and they give some concrete benchmarks.

Data encryption of sensor nodes is very important in body area networks (BANs) since the physiological data of an individual are highly sensitive. However, past encryption methods have small key space, which makes them vulnerable to attacks. In this paper, we propose a new encryption algorithm based on combined chaos. Firstly, Logistic and Kent chaotic mappings are introduced to produce two sub-matrices, and then a combined matrix is generated to perform XOR operation with the original data for encryption. The experimental results indicate that the proposed algorithm has a large key space, high key sensitivity and excellent attack resistance ability, and is feasible in privacy protection of BAN system.

Mobile learning when stored in a cloud server allows contents to be gathered and accessed using mobile devices connected with the cloud. The present problems of limited computing capacity and small space for storage in mobile phones has inspired the blend of mobile learning and cloud computing. This paper primarily focuses on Homomorphic Encryption to achieve privacy over encoded data or search the encrypted information, which is the current research area of majority of the knowledge experts. In this paper, we suggest Shifted Adaption Homomorphism Encryption (SAHE), which is regarded as the better option for all the current research going on. SAHE implements the smallest public key of 32 bit and is able to encrypt integer and real numbers. A major issue in this field of research is difficulty in protecting user's questions, which is addressed by conceiving a public key encryption technique which is based on the reversed index. Our schema preserves search efficiency using inverted index, by solving one time only search drawback encountered in earlier research works. This method is appropriate for mobile learning since the suggested algorithm will not use the mobile memory or power.

Color image can provide more information than gray image, so it is used more widely in the field of the communication. In recent years, how to safely encrypt images has received increasing attention. Numerous previous image encryption algorithms are based on the symmetric encryption algorithm, but each pair of users communicating with symmetric encryption algorithm can only use the key that others do not know, so when the sender communicates with a receiver multiple times or sends the message to multiple receivers, the key number will grow at a geometric rate, and key management will become a burden on the users. In this paper, we propose an asymmetric image encryption algorithm for the advantages that the key groups and the number of keys in secret information transmission among multiple people are very small, and key transmission mode is relatively simple and secure. In our algorithm, first, the plain image is compressed and then the color image is encrypted by using the improved 4D cat map followed by asymmetric encryption which is based on elliptic curve ElGamal encryption, and finally, the encrypted image is globally diffused. The performance analysis is performed on key spaces, key sensitivity, the capability of resisting statistical attacks, differential attacks, known plaintext attacks and chosen plaintext/ciphertext attacks and quality evaluation metrics of decrypted image. Simulation results show that the proposed algorithm has better security comparing with other algorithms.

Usage of EC operations as initial random generator and encrypting through AES to generate new pseudo random to mask whole image pixels.Simulations and analysis results show that cooperation of AES and EC random numbers makes great results in randomness and image encryption field.Comparable security and speed with other trend schemes like chaos based encryptions. Elliptic Curve Cryptography (ECC) has proven to be an effective cryptography. ECC has its own advantages such as efficient key size compared to other Public Key Infrastructures. This paper exploits the Elliptic curve random generator defined by National Institute of Standards and Technology (NIST) to generate a sequence of arbitrary numbers based on curves. The random generation phase is based on public shared key and a changing point G, which is a generator of a curve to obtain random sequences. Then, Advanced Encryption System is applied to these sequences acquiring arbitrary keys for encrypting image. Using AES alongside well distributed randoms provides a prominent encryption technique. Our experiments show that the proposed method fulfills the basics of cryptography including simpleness and correctness. Moreover, the results of the evaluation prove the effectiveness and security of the proposed method.

This letter presents an efficient polar code-based physical layer encryption (PLE) scheme with a short key length in comparison to the conventional symmetric key cryptosystems. By using the properties of polar codes, we consider several efficient techniques to reduce the key length and the computational overhead of the presented PLE scheme. Moreover, the results of the security analyses show that the proposed scheme has a high level of security against conventional attacks on the PLE schemes. In fact, reducing the key length and the computational overhead of the presented PLE scheme has no effect on its security level, which makes it suitable for secure mobile communication devices with limited resources.

In the past decade, with the development of data-sharing on cloud storage, people can access their personal or commercial data stored in different systems or devices anytime and anywhere. However, the shared data is distributed over many cloud storages. This may increase the risk of unauthorized access or even insider threats. Many commercial cloud storages provide data encryption service with extra charge; however, such service often encrypts data by using only one encryption key. When the authorized users of one group would like to access the shared data, they need to own the same decryption key, i.e., group key, which may rise the risk of data leakage, especially when the key is hacked. Multi-key encryption is another way to protect the shared data. But it is hard to manage multiple keys and share them with other authorized users, especially in a cloud environment. To provide a secure and effective data sharing method in a cloud environment, in this paper, we construct a secure cloud data encryption protocol, named the E nvironmental Ma tching key based D ata- S haring protocol (EMaDS in short). The EMaDS encrypts shared data by using one encryption key which combines several environmental matching keys derived from authorized user’s password and a trust device’s hardware/software configuration. Our security analyses show that the EMaDS is able to resist machine-specific data leakage, replay attack, eavesdropping attack, impersonation attack, forgery attack, and known-key attack. Besides, the mathematical proof also shows the probability with which to generate the same environmental matching key by using the same trusted device is less than 1 w m × w ! , where w is the number of parameters of a trusted device, and m is the number of parameters chosen for generating environmental matching key. When the trusted device is different, it is absolutely impossible to generate the same environmental matching key. These analyses conclude that the EMaDS is very suitable for group data sharing under heterogeneous environments and is practically useful in business.

To protect receiver privacy, researchers constructed anonymous multireceiver encryption by implanting anonymity in multireceiver encryption. It allows a sender to produce the identical ciphertext for multiple designated receivers. Every designated receiver can decrypt the ciphertext, but does not know who the other designated receivers are. Recently, several anonymous multireceiver identity (ID)-based encryption (AMIBE) schemes were proposed without the utilization of certificates. However, these AMIBE schemes are not efficient because their decryption cost of each receiver grows linearly with the number of the designated receivers. Moreover, all the ID-based cryptographic schemes suffer from the key escrow problem, which has been resolved by using certificateless public key settings. Very recently, Islam et al. proposed an anonymous multireceiver certificateless encryption (AMCLE) scheme. However, the encryption cost of a sender is quadric with the number of designated receivers, whereas the decryption cost of each receiver is linear with the number. In this paper, we propose an efficient AMCLE scheme with constant decryption cost, namely, the required decryption cost of each receiver is independent of the number of receivers. When compared with previously proposed AMIBE and AMCLE schemes, our scheme solves the key escrow problem and improves the efficiency of encryption/decryption significantly as well.

In this work, we investigate how to protect public key encryption from both key-leakage attacks and tampering attacks. First, we formalize the notions of chosen ciphertext (CCA) security against key-leakage and tampering attacks. To this goal, we then introduce the concept of key-homomorphic hash proof systems and present a generic construction of public key encryption based on this new primitive. Our construction, compared with previous works, realizes leakage-resilience and tampering-resilience simultaneously but completely independently, so it can tolerate a larger amount of bounded-memory leakage and be instantiated with more flexibility. Moreover, it allows for an unbounded number of affine-tampering queries, even after the challenge phase. With slight adaptations, our construction also achieves CCA security against subexponentially hard auxiliary-input leakage attacks and a polynomial of affine-tampering attacks. Thus, to the best of our knowledge, we get the first public key encryption scheme secure against both auxiliary-input leakage attacks and tampering attacks.

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.

For the last 3 decades, the inclusion of chaos for the encryption of multimedia information is considered as a remarkable aspect of nonlinear dynamics. In this article, chaotic system along with substitution box is used for image encryption. Substitution box is constructed by the group action of the projective general linear group over a finite field. On multiple attempts, using the same security key the host image gives a different encrypted image which is the main feature of this scheme. For secure communication, this idea of chaos-based image encryption along with substitution box shows relatively improved results as depicted in simulation and security analysis. The scheme demonstrates resistance against image processing attacks.

Advanced Encryption Standard was published as Federal Information Processing Standard by National Institute of Standards and Technology in 2001. AES is a symmetric non fiestel block cipher cryptographic algorithm that encrypts and decrypts the data block of 128 bits using different key sizes (128, 192, 256). Based on the block sizes, the number of rounds of encryption and decryption operations and the number of subkeys generated from the main key differs. In this proposed algorithm, the subkey generation architecture is altered to speed up the process of generating the subkeys from the main key. The proposed architecture is simulated and is implemented in FPGA Virtex 5 XC5VLX50T and it is found that the proposed architecture generates all the subkeys by saving 50% of the time taken by architecture proposed in 2001. This paper discusses the implementation of the new proposed algorithm for encryption and decryption process of ECG signals for the purpose of secure communication.

Networked control systems with encrypted sensors measurements is considered. Semi-homomorphic encryption, specifically the Paillier encryption, is used so that the controller can perform the required computation on the encrypted data. Conditions on the parameters of the encryption technique are provided that guarantee the stability and the performance of the closed-loop system. The results are subsequently extended Laplacian based distributed systems, such as formation-seeking algorithms. It is shown that the problem of figuring out the state measurements of the neighbouring agents of a compromised agent upon using the proposed algorithm is numerically intractable.

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.

A new symmetric key image encryption scheme based on hyper-chaotic Lorenz system is proposed. The encryption process and the decryption process are identical in the proposed scheme. They both include two diffusion operations, one plaintext-related scrambling operation and three matrix rotating 180 degrees operations. The hyper-chaotic Lorenz system is employed to generate the secret code streams to encrypt the plain image, and to implement the diffusion process with XOR operation. The plaintext-related scrambling is used in this scheme to make different plain images correspond to different secret code streams even when the secret keys are the same, so that the scheme can fight against the chosen/known plaintext attacks. Simulation results show that the proposed scheme has the merits of high encryption speed, large key space, strong key sensitivity, strong plaintext sensitivity, good statistical properties of cipher-text, and etc., and can be used in practical communications.

Rapid growth of digital data and their security concerns increases the significance of enhancing advanced encryption techniques. Encryption is the backbone of secure communication in networks and the physical process of scrambling and permuting data in order to make them impossible to understand for unauthorized users. This paper proposes a novel audio signal encryption method, based on a mixture of three chaos functions. Due to the reversibility of the chaos functions, the decryption process is the inverse of the encryption process. This method was applied to audio signals with various sizes and the encoded messages were compared to the original ones. Simulation results and theoretical analyses show that the proposed approach offers a significant gain in terms of robustness and computational complexity.

Cryptographyis the process of data hiding from unauthorised users. Historically, the term “Cryptography” has been associated with the problem of designing and analyzing encryptionschemes (i.e., scheme that provide secret communication over insecure communication media). With the growth of internet secure data transmission is more and more essential and important. Sometime single encryption technique is not sufficient to protect the valuable data. We developed a new algorithm which can change the encryptiontechnique with change of plane textpattern to enhance the confusion and as well as diffusion.

A data owner (DO) is usually store large amounts of data in cloud for saving the cost on local data management. Without any data protection mechanism, cloud service provider (CSP), however, can fully gain access to all data of the user. Data owner can fully control the access policy associated with his data which to be shared. However, CP-ABE is limited to a potential security risk that is known as key escrow problem whereby the secret keys of users have to be issued by a trusted key authority. The proposed system revisits the attribute-based data sharing scheme in order to not only to solve the key escrow issue but also to improve the expressiveness of attribute, so that the resulting scheme is friendly to cloud computing applications. The proposed system has an improved two-party key issuing protocol that can guarantee that neither key authority nor cloud service provider can compromise the whole secret key of a user individually. This brings a potential security risk to the user, since CSP may compromise the data for commercial benefits. Ciphertext-policy attribute-based encryption (CP-ABE) has turned to be an important encryption technology to tackle the challenge of secure data sharing.

We develop a new cryptosystem for fine-grained sharing of encrypted data that we call Key-Policy Attribute-Based Encryption (KP-ABE).As more sensitive data is shared and stored by third-party sites on the Internet, there will be a need to encrypt data stored at these sites. One drawback of encrypting data, is that it can be selectively shared only at a coarse-grained level (i.e., giving another party your private key). Instead of trusting a middle layer authority , we perform an end to end encryption using the Key-Policy Attribute-Based Encryption (KP-ABE).Moreover the proposed system is proved to be secured under standard assumption. With the number of the files increasing, the advantages of our scheme become more and more usefull.

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.

A new structure of pre-modular, permutation, and diffusion (PPD) cipher for image encryption is proposed.Solve the low sensitivity of the plain-image when meeting invariance of pixel summation.Self-adaptive encryption scheme is implemented, and no extra transmission is needed.The keystreams used for encryption are designed dependent on the plain-image. Differing from the traditional permutationdiffusion architecture, an efficient symmetric image encryption algorithm is designed in this paper. To resolve the issue of low sensitivity of a plain-image, which is measured by a unified averaged changing intensity and the number of changing pixel rate, pre-modular operation is proposed to be used for pre-processing a classical encryption algorithm. Because of the invariance of pixel summation in the plain-image before and after pixel positions exchange, the keystream used for the permutation operation is designed to be dependent on the plain-image. Since for most encryption algorithms it is hard to implement the diffusion operation in relation with the plain-image dependence, a self-adaptive encryption scheme is proposed as a remedy. Consequently, the keystream for diffusion becomes dependent on the plain-image, which still satisfies the requirement as a symmetric cipher. To that end, by taking full advantage of the chaotic intertwining logistic map and its unpredictability, a new cipher with pre-modular, permutation and diffusion is designed for image encryption, which is then simulated and tested. Numerical experiments and security analysis demonstrate that the new cipher is secure enough for image communication over the open network.

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.

Hierarchical identity-based encryption is an important extension from IBE and has found many applications in the network world. Private key revocation is a crucial requirement for any public key system. In this paper, we propose a novel revocation method for the hierarchical identity-based encryption. Existing revocable hierarchical identity-based encryption schemes have several disadvantages: the key update size increases logarithmically with the number of users in the system, the public information of key update received by each user is different and always related to the level of the identity hierarchy and the security proof of the revocable scheme is very complex. In our scheme, cryptographic accumulators are used to compress hierarchical levels and revoked users’ information into constant values. So we achieve almost constant size of private key update which is irrelevant with the user number in the system. Because of the compression of hierarchical information we can use simple dual system encryption techniques to prove our scheme to be fully secure under several common assumptions without resorting to complex nested dual system encryption techniques.

This paper proposes a new approach to the encryption of speech intended to be transferred on an insecure channel. The proposed technique is based on stream encryption where the original speech is pre-processed in order to select the relevant data for encryption by removing the unvoiced parts of the signal. In addition to reducing the size of the speech signal, the selection process also reduces the encryption and decryption times. The selected data is encrypted using a pseudo-random generator to make the information unable to understand by an intruder. The used pseudo-random generator is based on two 256-bits shift registers, one is linear and the other non-linear. This generator allows encryption in higher dimensional space which expands the key space and, therefore, improves security against brute force attack. Various analyzis such as histograms, key space, key sensitivity, correlation, brute force attack, signal to noise (SNR) and peak signal to noise ratio (PSNR) have been performed. The analysis shows that the proposed scheme is computationally simple, efficient with superior performance compared to other systems presented in the literature.

Encryption is a method, for the protection of useful information, which is used as one of the security purposes and steganography is the art of hiding the fact that communication is taking place, by hiding information in other Information. In this article at first, plain text message as a security information is converted to the (Quick Response Code) QR-code image and then we proposed a new secure hybrid algorithm for the encryption and steganography of generated QR-code. In this article image encryption is based on two-dimensional logistic chaotic map and AES algorithm and steganography technique is based on LSB algorithm. In addition, Huffman algorithm has come out as the most efficient compression technique and we can use Huffman algorithm to compress encrypted QR-code. Experimental results show that the scheme proposed in this article has a high security and better QR-Code images encryption and steganography quality.

One of the interesting secure applications in the smart city is broadcasting information to legitimate users, desirably with user privacy. Broadcast encryption has been considered as a useful tool to protect the data security and provide data access control. Most works in broadcast encryption are about the data security, while less attention is paid to the data access control and the identity privacy. In this paper, based on broadcast encryption, we present a scheme called Fully Privacy-Preserving and Revocable Identity-Based Broadcast Encryption, which preserves the data privacy and the identity privacy of the receiver as well as the revoked user. The data can be securely protected and only the authorized user can access the data. The revocation process does not reveal any information about the data contents and the receiver identity. The public learns nothing about the receiver identity and the revoked user identity. These properties lead to nice applications in the smart city where identity privacy is desirable. The security of our scheme is proved to be semantically secure in the random oracle model.