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Network slicing is a logical network function that supports communication service requirements for specific usage scenarios or business models. It has become an essential factor in solving future network architecture. In recent years, heterogeneous network slicing between multiple autonomous domains has emerged, with significant limitations compared to single-domain networks. Data sharing in heterogeneous network slices challenge the confidentiality of sensitive data significantly. Preventing sensitive data from leaking and protecting core data have become urgent problems to be solved. Therefore, we propose a multi-party (multi-sender to multi-receiver) anonymous authentication scheme on certificateless cryptography(CLC) and identity-based cryptosystem(IBC) institutional domain Internet of Vehicles(IoV) to smart healthcare. Our scheme realizes heterogeneous communication between multiple senders and multiple receivers, and uses different system parameters for heterogeneous cryptographic systems. In this work, the limitation of one-to-many or many-to-one communication in existing heterogeneous networks is broken through. The proposed work utilizes the pseudo-identity generated by the trusted authority to communicate in IoV slices, ensuring the anonymity of the sender; The authorization Center TA can uniquely determine the true identity of the vehicle through pseudo-random values for traceability. What is more, the Lagrange interpolation formula is employed to prevent the leakage of the identities of smart healthcare slices, ensuring the anonymity of the receiver. Under the random oracle model, the proposed scheme has proved to satisfy unforgeability, confidentiality, and anonymity under the computational Diffie–Hellman problem. Experimental results indicate that our proposal achieves better performance than existing schemes. [ABSTRACT FROM AUTHOR]

For secure and efficient transmission or storage, data files are commonly compressed and encrypted. In this work, we introduce a cost-effective encryption method of files as a built-in component of a lossless compression algorithm, thus avoiding the added cost of employing two separate processes. We have shown in earlier studies that preprocessing data with Burrows–Wheeler Transformation followed by Inversion Ranking transformation in advance of the utilization of an entropy coder resulted in an extremely effective general-purpose lossless compression technique. In our proposed algorithm, we isolate the inversion frequency vector obtained from the Inversion Ranking transformation and transmit the compressed file. Since the inversion frequency vector is necessary for decompression, we use it as our secret key and transmit it over a secure channel. Compared to the size of a data file, its frequency vector is rather small. Thus, encrypting only the inversion frequency vector, instead of the entire compressed file, results in substantial savings in computational cost. We demonstrate that the proposed technique is effective and resistant to common attacks on image and audio data sets. [Display omitted] • BWIC is an effective general-purpose lossless data compression algorithm. • Each input data set generates its unique inversion frequency vector, thus a unique secret key. • Our proposed technique does not negatively affect compression efficiency. • Compared to the size of a data file, its frequency vector is rather small. • Resistance of our algorithm to common attacks is demonstrated on image and audio data sets. [ABSTRACT FROM AUTHOR]

In recent years, cloud data broadcasting system has attracted intensive attention due to its universal applicability in various Internet-of-Things enabled real-life scenarios. Cloud data broadcasting with simultaneous individual transmission is an exciting data broadcasting variant that empowers any data broadcaster to distribute encrypted broadcast data to a subscribed consumer group and the personalized transmission to each group member simultaneously. Recently [IEEE Transactions on Broadcasting (2020)], a certificate-based data broadcasting with simultaneous individual transmission scheme (Chen et al., 2020) is proposed with the aim to solve both key-escrow problem and certificate management problem, and it is claimed to provide subscriber's outsider anonymity under the nonstandard q -type security assumption with the existence of random oracles. Unfortunately, we can show that this most recent work of Chen et al. (2020) is not secure against insider attacks, meaning that their protocol cannot trace the system's traitor consumers who can resell the sensitive information for their own profit without valid authorization. Besides, the design of Chen et al. (2020) has significantly high communication bandwidth that is approvingly inconvenient for the Internet-of-Things facilitated low-powerful multimedia devices to reduce unnecessary burden on the encryption costs. We design a provably secure adaptive identity-based data broadcasting technique having simultaneous individual transmission with unbounded number of consumers that can concatenate two mutually orthogonal functionalities, namely consumer's outsider anonymity and traitor consumer traceability, in a cost-efficient way. Our framework exploits the most secure and advanced asymmetric Type-3 bilinear maps to defend against fault attacks and realizes security in the standard provable security model without the existence of any random oracle. On a positive note, our construction eliminates the q -type security assumption that is so far a plausible achievement compared to all the existing schemes in this area. [ABSTRACT FROM AUTHOR]

In recent times, prediction error expansion (PEE) based reversible data hiding (RDH) schemes have gained significant traction due to their performance in terms of embedding capacity and image quality. However, the major part of their performance is dependent on how good the prediction has been. For a good prediction, various predictors such as median edge detection (MED), rhombus mean, least square, convolution neural network based predictor (CNNP) have been introduced. In this paper, a review of the working predictors being used in PEE-RDH is presented and discussed. In addition, a new predictor using extreme gradient boosting (XGBoost) is introduced in reversible data hiding. The XGBoost predictor makes use of a machine learning algorithm, where several optimization techniques are combined to get accurate results. To evaluate the performance comprehensively, experimental results considering different test images have been used and analyzed. From the analysis, it has been found that the XGBoost provides better prediction accuracy than some of the existing predictors. However, its performance is not up to the level of some other popular predictors such as least square, CNNP. • The paper first presents a detailed a review of various predictors being used in RDH. • The rhombus mean predictor is found to be the simplest with prediction accuracy. • A new XGBoost predictor has also been introduced for RDH. • The performance analysis and comparisons are also presented. • Further, future research directions have been recommended. [ABSTRACT FROM AUTHOR]

With the continued evolution of three dimensional (3D) object presentation and usage, the security of such objects has become an increasingly desirable research area. Previous efforts mostly concentrated on the encryption of point clouds, solid models, meshes, and 3D textured models. The (texture map) part of meshed 3D objects was overlooked by previous encryption techniques of 3D meshed objects in spite of its importance because they require preprocessing to be extracted. Therefore, this paper provides a system for the full encryption of 3D textured objects with their texture maps. It provides an improved system based on an existing flexible cryptosystem named Flexible cryptosystem based on Cellular Automata (FcCA). The FcCA system has two drawbacks. One drawback is shuffling plain data without changing their values, which yields the same histogram and nonstandard encryption ratios. The other drawback is the need for many generations to make the keyspace very large, which is unsuitable for the large size of textured object data. This work overcomes these drawbacks of FcCA and fully encrypts 3D textured objects with their texture maps. The improvements to FcCA include making intersect start points change with every generation and encrypting the values of plain data while shuffling them using cellular automata. At first, the plain 3D object is extracted to vertices, faces, and texture, in addition to its texture map. After that, extracted data are encrypted using the proposed improved FcCA (iFcCA) cryptosystem. Implementation and analysis of this new system showed its preponderance as it can encrypt and decrypt 3D textured objects better than FcCA and other existing methods. Moreover, it reduces the need for many generations of cellular automata, and consequently, reduces execution time. In addition, iFcCA has a very robust key, and it can resist different types of attacks. [ABSTRACT FROM AUTHOR]

This paper proposes a reversible data hiding scheme for encrypted images with SHE (Somewhat Homomorphic Encryption) based on sorting block-level prediction-error expansion (SBPEE). The image provider divides the image into 2 × 2 image blocks and uses SHE to protect the content of the image. In encrypted images, the data hider embeds the secret data with the method of SBPEE, which is based on the pixel redundancy within each block. And the sorting technique shows a good performance at low embedding rate. With the watermarked encrypted image, if the receiver has only the data hiding key, he can extract the additional data. If the receiver has both the data hiding key and the encryption key, he can extract the additional data correctly and recover the original image without loss. The experimental results show that the performance of the method is better than that of the existing similar methods when the embedding rate is low and is consistent with the existing methods when the embedding rate is high. [ABSTRACT FROM AUTHOR]

Lightweight block ciphers based on symmetric cipher are tailored to addressing security issues for highly constrained Internet of things devices. In this article, we explore general software implementations of lightweight ciphers on GPU architectures, with a special focus on LED, Piccolo and PRESENT. First, we implement the lightweight block ciphers using lookup table based technique. Then we analyze the effect of different factors on the encryption performance, such as the size of lookup table, the parallelism level, the use of different type of memory and the idle state caused by data transmission. We evaluated the three lightweight block ciphers on Nvidia Tesla V100 and Nvidia GTX1060 GPUs. Finally, the experimental result shows a great improvement on all the investigated ciphers compared to the unoptimized implementations. [ABSTRACT FROM AUTHOR]

Reversible data hiding in encrypted domain has been discussed for years. However, the performance of the existing algorithms is generally not satisfactory for the difficulty in signal processing in encrypted domain. In this paper, a high capacity reversible data hiding scheme for encrypted covers is proposed. The cover is first partitioned into non-overlapping blocks and encrypted effectively with homomorphism but without data expansion. Then a histogram shifting algorithm based on prediction error extension is introduced to achieve high embedding capacity of the scheme. The parameters in embedding process can not only adjust the embedding rate but also provide pretty good support for the security of the embedded data. The algorithm can achieve full reversibility at high embedding rate without extra data, and the embedding rate can reach to 2 bpp (bit per pixel). The experimental results verify the effectiveness of our solution, and show that the proposed scheme has outstanding performance in both capacity and quality compared with similar algorithms. [ABSTRACT FROM AUTHOR]

Conditional proxy re-encryption allows a semi-trusted third-party proxy to convert Alice's ciphertext that meets a certain condition into another set of ciphertext. Meanwhile, the proxy cannot obtain any valuable information in the process. Nevertheless, a single re-encryption condition is difficult to meet the needs of practical applications, and the existing conditional proxy re-encryption scheme cannot flexibly control the conversion conditions. To solve this problem, this paper proposes a multi-conditional proxy broadcast re-encryption (MC-PBRE) scheme for file sharing systems. In our scheme, a single user can delegate the decryption rights of the encrypted file to a group of users. At the same time, users can set any number of conditions to control the user group decryption permissions. This paper demonstrates the security of the scheme for chosen-ciphertext attacks in the standard model. Furthermore, the program can resist collusion attacks, which means that the agent cannot collude with the user group to get the private key of the principal. [ABSTRACT FROM AUTHOR]

• Multi-secret image sharing schemes have high computational complexity in decoding. • Arithmetic modulo-based scheme has low computational complexity but is not secure. • To overcome these issues, arithmetic operation-based scheme is proposed. • Proposed scheme fulfills security criterion and reduces computational complexity. • Company organizer can utilize universal share for managing multiple secrets. Visual secret sharing (VSS) scheme is an encryption technique to hide secret message into two or more meaningless images, called as shares. Shares are stack together to decrypt the secret message using human visual system. To share many secrets, multi-secret image sharing schemes are often used. Diversity in sharing multiple secrets is using the universal share. Company organizer shares multiple secret images using this common share. Computation cost is the major drawback of such scheme. This study presents computationally efficient arithmetic-based multi-secret image sharing scheme using the universal share. Binary arithmetic-based scheme utilizes distinct value selecting function while encoding and decoding of secret images. Distinct value selecting function enhances randomness property of shares and fulfills threshold property. Thus, the proposed method provides computationally efficient method while satisfying threshold security criteria. [ABSTRACT FROM AUTHOR]

The booming growth of the Internet of things(IoT) has improved the productivity of companies and improved people's quality of life. However, as a growing number and variety of connected devices are introduced into the IoT networks, not only are communication bandwidth and storage severely challenged, but potential security threats are escalating. Therefore, we consider using compressive sensing(CS) in the IoT system to solve this problem. The solution we designed solves three main security threats in the IoT, the perception layer, the transport layer and the application layer. In our work, the gateway node of the perception layer provides the function of anonymous identity authentication and information authentication, which can not only prevent external attackers from obtaining private information from the gateway node, but also solve security problems such as identity authentication and man-in-the-middle attack in the transmission layer. Meanwhile, our scheme handles the ciphertext integrity protection and energy leakage in existing CS encryption(CSE) schemes, protecting the security of application layer privacy data. And our scheme provides a secure key sharing method, which improves the security of the system. In addition, we designed two fault-tolerant models to ensure that the ciphertext can still be decrypted correctly when the cloud server fails in the IoT environment. The use of the replaced sparse vector instead of the random matrix method in the traditional CSE scheme improves the quality of recovery while saving a large amount of storage space. Simulation results show that our scheme improves the overall compression and recovery performance compared to other CSE schemes. [ABSTRACT FROM AUTHOR]

Personal health record (PHR) system has become an important platform for health information exchange, in which patients can effectively manage and share personal health information in cloud storage. In general, all health information will be encrypted before they are uploaded to the cloud server. However, the cloud server is unreliable and the sensitive information of users may be disclosed in this process. The general encryption algorithm cannot protect both confidentiality and privacy of the uploaded information. Attribute-based encryption (ABE) provides a solution to it. In this paper, we propose a privacy-preserving decentralized ABE scheme for secure sharing of PHR based on Lewko and Waters′s scheme, in which an anonymous secret key issuing protocol is used to hide GIDs. This protocol can make the authorities generate the correct decryption key for users without knowing their GIDs. In addition, the one-way anonymous key agreement is used to hide the attributes in the access policy. The presented scheme keeps the security of the Lewko and Waters′s scheme and removes the random oracle. Finally, we show that the security of the proposed scheme is reduced to static assumptions based on dual system encryption instead of other strong assumptions. [ABSTRACT FROM AUTHOR]

Proxy re-encryption (PRE) can share ciphertext data without leaking the decryption key of the data owner in cloud computing. Because of the special property, PRE achieves good reliability and secrecy. Nevertheless, most of the proposed proxy re-encryption schemes are based on the number theoretic problem and cannot resist quantum attacks. In addition, most existing researches over lattice focus on the single bit encryption, which leads to low efficiency. Therefore, according to these problems, an efficient identity-based multi-bit proxy re-encryption over lattice in the standard model is constructed, which enlarges the plaintext space and improves the efficiency. What's more, the proposed multi-use and bidirectional scheme is proved to be CPA secure in the standard model. [ABSTRACT FROM AUTHOR]

This paper introduces a novel Logarithmic Chaotic Map (LCM) that is inspired by the well known quadratic map. The chaotic dynamic of the proposed map LCM is thoroughly investigated and its chaotic properties are found to be superior in comparison with the existing maps in the literature. In addition, a new encryption algorithm is proposed that is based on LCM. The chaotic output generated from LCM passed through all 15 National Institute of Standards and Technology (NIST) statistical tests thus confirming its randomness. The proposed encryption algorithm is best suited for encrypting numeric sensor data values preferably for IoT applications and has been found to be highly resilient to security attacks. [ABSTRACT FROM AUTHOR]

In this study, a new color image encryption model that uses an intertwining logistic map based confusion mechanism and coupled map lattice based diffusion process. It incorporates mixing based on pseudo random number generator to ensure shuffling incase of same pixels, intertwining logistic map based confusion mechanism enhance the key sensitivity in the model. Finally, Couple map lattice based diffusion is utilized in the model to change the pixels in a way that even one-bit change in a pixel of plain image leads to a change in large number of pixels of the cipher image. The proposed encryption method enhance the security and results in better Number of pixel change rate (NPCR) and Unified average change intensity (UACI) scores. The correlation among the pixels of cipher image is reduced to be negligible. Corresponding results suggest that the proposed model is highly secure as compared with chaos based algorithms for image encryption application. [ABSTRACT FROM AUTHOR]

With the increasing popularity of pervasive devices such as smartphones and Internet-of-Things devices, mobile e-Healthcare has become a research trend in recent years. Disease risk prediction using big data analytics techniques is one popular e-Healthcare research focus, and one associated research challenge is ensuring the privacy of user and patient data. In this paper, we propose a new efficient and privacy-preserving pre-clinical guidance scheme (hereafter referred to as PGuide) for mobile eHealthcare, designed to offer both self-diagnosis and hospital recommendation services to users in a privacy-preserving way. To provide users the capability to present a detailed health profile for accurate disease risk prediction, we introduce a privacy-preserving comparison protocol (PPCP) in PGuide, which will improve the accuracy of disease risk prediction. We also employ a single-attribute encryption technique to devise a privacy-preserving hospital recommendation service in PGuide, which can further guide users to choose a hospital appropriate for their visit after conducting a self-diagnosis. We then prove that PGuide can achieve the privacy-preservation requirements in both self-diagnosis and hospitals recommendation services. We also conduct a number of experiments, which demonstrate the efficiency of PGuide, in terms of computational cost and communication overhead. [ABSTRACT FROM AUTHOR]

Transmission of protected content via commercial channels is a common problem observed in information security. The secrecy of such content can be preserved using various encryption techniques. This study proposes a novel speech encryption method that provides high level of security and uncertainty to the encrypted data using a variable-length encoding technique based on the Collatz conjecture. The efficiency of the proposed method is evaluated by testing 500 encrypted audio files in terms of data correlation, uncertainty and disorder, time expansion ratio, computational cost, security key space size and key sensitivity. Results indicate that the uncertainty levels (7.5) and disorder levels (1.2) of the encrypted files are almost similar to the maximum possible entropy and disorder levels of 8 and 2, respectively. Compared with other approaches, this method has larger key space with extremely higher key sensitivity. Thus, the proposed method can be essentially used in information security because it produces encrypted signals with high level of security and uncertainty. [ABSTRACT FROM AUTHOR]

Nowadays, internet is the medium through which people are sharing digital images. However, security is an issue in sharing of those images. Encryption techniques play an important role for the security of images. In this paper, an efficient colour image encryption scheme is proposed using multiple piece-wise linear chaotic map (PWLCM) systems. The proposed scheme first performs two-times multi-way block-based rotational permutation operations and then row-column rotational permutations. Finally, it performs row, column, and block diffusion operations. This scheme is simple and secure because it involves only simple rotational permutation operations using only PWLCM systems. Also, this scheme is efficient because it requires less computations and less simulation time to encrypt colour images. The advantages of this scheme are high key space, high security, simplicity and high efficiency in terms of computational complexity and simulation time. The simulation outputs and the security analyses indicate that the proposed method has better performance in terms of encryption efficiency, security, and resistivity for most of the common attacks. [ABSTRACT FROM AUTHOR]

As digital data are explosively generated nowadays, data management becomes a critical problem, which makes cloud storage services important and popular. In reality, the storage overhead can be reduced significantly by performing date deduplication. Among the outsourced data, some of them are very personal and sensitive, and should be prevented for any leakage. Generally, if clients conventionally encrypt the data, deduplication is lost. Message-locked encryption (MLE) is a cryptographic primitive supporting encrypted data deduplication. A secure client-side deduplication scheme can be built upon MLE to reduce both communication and computation overhead for cloud storage systems, where a client interacts with the cloud server to check the duplicate data and only the data which has not been outsourced by other clients before is required to be uploaded. However, existing client-side encrypted data deduplication schemes are confronted with brute-force attacks that can recover files falling into a known set. Furthermore, existing schemes are vulnerable to illegal content distribution attacks, where the adversary can distribute data to other users via the cloud server without detecting. In this paper, we propose a secure and efficient client-side encrypted data deduplication scheme (CSED). In CSED, a dedicated key server is introduced in generating MLE keys to resist brute-force attacks. We propose a Bloom filter-based proofs of ownership (PoW) mechanism and integrate it into CSED to resist illegal content distribution attacks. Moreover, a hierarchical storage architecture is employed to improve the I/O efficiency on the cloud server. Security analysis and performance evaluation demonstrate that CSED is secure and efficient. [ABSTRACT FROM AUTHOR]

This research paper introduces a novel symmetric encryption algorithm that provides the confidentiality security service without leaking enough information about the exact encryption algorithm or other cryptographic parameters to anyone except the legitimate receiver. This is achieved by utilizing a set of sound existing symmetric encryption algorithms, namely, the Advanced Encryption Standard,MARS,RC6, Serpent and Twofish. The identity of the algorithm used to secure the current message, along with other cryptographic parameters (e.g. mode of operation, key length), are hidden from anyone except the legitimate receiver. These parameters are shared securely between communicating parties by utilizing some of the symmetric key bits. The cipher suite in addition to the encryption key, changes systematically and securely with every new message, leaving the opponent with no enough information to launch any effective attack. The algorithm performance is tested, and the overall performance is close to the performance of conventional encryption with a delay of about 16.52 CPU Cycles per message. From a security point of view, the possibility of cryptanalysis is diminished significantly, as no party except communicating parties has any knowledge of the cryptographic parameters in use. [ABSTRACT FROM AUTHOR]

There are tremendous impacts of advancement in information and telecommunication technology over the use of multimedia data. Multimedia data especially videos are stored and transmitted through the wired and wireless network, where they can be easily accessed. Thus, safeguarding the video data from unauthorized access and protecting the integrity and authenticity has become mandatory for transmission as well as storage. Encryption is one of the best technologies in Digital Rights Management (DRM) scheme which is used to protect copyright works. This paper reviews some previous and recent works for encryption techniques of H.264/AVC video encoders. The reviewed work has been categorized based on the area where the encryption scheme is applied. [ABSTRACT FROM AUTHOR]

Many ciphers suffer from weak-key issues. This problem is due to the simplicity of the key schedule algorithm. Unfortunately, the cipher designers have not paid much attention to the sub-keys generation as the cipher itself. Thus, any attacker can find many attractive properties between sub-keys such as statistical pattern, linearity, low avalanche criteria, etc. Many ciphers use a large key during encryption (e.g. 128 bits). This makes it practically impossible to test all keys, allowing all of today's ciphers to be potentially vulnerable to the weak-key issue, including AES. Accordingly, this paper sheds light on the advantage of using chaos in sub-keys generation by developing a new key schedule algorithm based on the logistic maps. We name this algorithm CKSA. Compared to several existing key schedule algorithm, CKSA provides a good avalanche effect. It is a one-way function, and its size is flexible, i.e. the size of the sub-keys is not fixed, which allows to many ciphers the possibility of using it. Further, CKSA ensures confusion and diffusion. It resists differential attacks and avoids linear key correlation between sub-keys while ensuring a high degree of randomization among them. [ABSTRACT FROM AUTHOR]

Bluetooth version 5.0 introduced flexibility in SSP pairing protocol. It introduced P-192 elliptic curve for devices that support all versions before 4.0 and P-256 elliptic curve for devices that support 4.0, 4.1, 4.2, and 5.0 versions. Despite enhanced security level, there is a possibility of capturing the Input-Output capability and public keys during the initial phase of pairing and thus impersonating them. This paper introduces enhanced Bluetooth Secure Simple Pairing protocol by augmenting two new security levels. The protocol commits for public keys and IO capability. This ensures that the information reaches to the legitimate pairing devices. Thereby attempts to reduce Man-In-The-Middle attack in the initial phase and strengthen the link/session key. [ABSTRACT FROM AUTHOR]

In this study, a novel cryptographic model that uses coupled map lattice is proposed for securing image. It incorporates mixing based on randomly generated secret key, sub-keys based substitution, confusion algorithm and coupled map lattice based diffusion process to enrich the security, sensitivity and robustness of the model. The control parameters of coupled map lattice and initial condition of chaotic systems are deduced using externally generated random secret key of 280-bit length. To make the encryption process more dependent on confusion and more sensitive to the encryption key, pixels of a channel are XOR-ed with pixels of other channel with an intelligent mix of sub-keys. Finally, the diffusion model based on coupled map lattice, binds the pixels in a way such that a single-bit change is reflected into a large number of pixels in the cipher image. Resistance to various kinds of attacks like plain text, brute force and statistical attacks are the important features observed in the proposed cryptographic model. Several studies related to correlation coefficients, histogram, anti-noise attacks, plain text analysis, NPCR, key sensitivity, UACI and key space analysis were carried out and corresponding results are given in detail. The simulation results yield an average NPCR score to be about 99.63% and UACI value 33.46%. A number of analysis performed and mentioned here, suggests the proposed model a potential candidate for image encryption application. [ABSTRACT FROM AUTHOR]

The private equality test (PET) is a special case of secure computation between two users who want to compare their private values for checking the equality without disclosing any information to each other if they do not equal. This paper considers the PET problem and its variants in the encrypted domain, which are useful in several areas such as private online-auction, queries in a database, data mining, and genomic computation in the cloud. For comparing two l -bit integers, we propose a private equality test (PET) protocol, denoted by (1,1)-PET, using somewhat homomorphic encryption secured in the semi-honest model. To support efficient computation of many equalities, we propose two more variants (1, k)-PET and (t, k)-PET, where t is the number of queries and k is the number of data. Here we exploit a batch processing for efficient execution of the equality test protocols both for computing (1, k)-PET and (t, k)-PET. To make these protocols efficient, we propose a method to pack multiple data into a single polynomial. Our packing method enables us to make the secure computation of these protocols in a few multiplications. In 2016, Cheon et al. [IEEE Trans. Inf. Forensics Security] showed an equality circuit for 10-bit integers and its application to database query processing using fully homomorphic encryption over the encrypted data. We demonstrate the efficiency of our (1,1)-PET protocol by showing the better performance than Cheon et al.'s equality circuit. In addition, our experiments on (1, k)-PET and (t, k)-PET protocols demonstrate their practicality. [ABSTRACT FROM AUTHOR]

Functional encryption (FE) allows to restrict decryption in a highly sophisticated fashion, whereas, functional signature (FS) enables to enforce arbitrarily complex control on signing capabilities. This paper introduces a new cryptographic primitive, termed as functional signcryption (FSC), which unifies the functionalities of FE and FS into a cost-effective formulation. FSC is a crucial step towards efficient implementation of modern digital communication and storage systems that demand advanced forms of confidentiality and authenticity simultaneously. Precisely, we make the following contributions: − First, we present a formal definition of FSC and carefully formulate its security requirements. − Next, we provide a generic construction of FSC supporting signing and decryption functionalities realizable by general polynomial size circuits , based on fundamental cryptographic tools, namely, indistinguishability obfuscation (IO) for circuits and statistically simulation-sound non-interactive zero-knowledge proof of knowledge (SSS-NIZKPoK). − Finally, we exhibit a number of representative applications of this interesting cryptographic primitive: (i) We develop the first ever attribute-based signcryption (ABSC) scheme for arbitrary polynomial size circuits from FSC. (ii) We show how FSC can be utilized to build SSS-NIZKPoK systems and IO for general circuits. This result in conjunction with our FSC construction can be interpreted as establishing an equivalence between FSC and the other two important cryptographic primitives. [ABSTRACT FROM AUTHOR]

Image scrambling is the conversion of images to unreadable format for security reasons. Encrypting an image with an acceptable level of security requires a cryptography system that follows the rules of confusion and diffusion. This paper introduces the SCAN method for scrambling and pixel rotation for diffusion. This image encryption method uses a knight tour to generate a scrambling key that is equal to the image size. The main advantage of this generator is that only a small initial value is needed to generate a full image size key. To realize confusion, a plain image is applied with an improved discrete diagonal SCAN (D-SCAN) method to generate a scrambled image for confusion. Then, to achieve diffusion, pixel values are changed by rotating all image pixels according to the generated keys. Results of statistical and security tests indicate that the proposed systems of D-SCAN and pixel rotation scheme can achieve excellent scrambling effect, high security, strong robustness against several attack types, and high sensitivity. [ABSTRACT FROM AUTHOR]

In recent years, reversible data hiding in encrypted images (RDHEI) has gained popularity as it enables the concealing of confidential information in anonymized host image. Because of this, conventional reversible data hiding (RDH) methods that utilize the spatial correlation of natural host images cannot be employed in RDHEI where the embedding is done in the encrypted image without reserving a room. To address this concern, this paper proposes a new RDHEI method based on popular pixel value ordering (PVO) strategy of the conventional high fidelity RDH. For this, the image pixels are first encrypted in blocks using novel difference-preserving encryption for maintaining the original difference among the pixels of each block. Next, a two-pass PVO (TPPVO) is employed for embedding. The TPPVO first sorts the pixels and then performs the embedding in two passes in such a way that high embedding capacity (EC) can be obtained while also ensuring reversibility. Experimental evaluations also demonstrate that the proposed TPPVO-RDHEI not only enlarges the EC approximately by 0.1130 bpp and 0.01 bpp for the smooth and complex images, respectively in comparison to the best performing related method, but also maintain the visual security while ensuring the complete reversibility. [ABSTRACT FROM AUTHOR]

Aiming at the privacy and security issues of sensitive speech data in cloud storage, and how to achieve efficient retrieval with privacy-preserving for encrypted speech data in cloud storage, a searchable encryption over encrypted speech retrieval scheme in cloud storage was proposed. Firstly, the data owner encrypts the original speech data adopting symmetric encryption algorithm Lorenz chaotic mapping. Secondly, the encrypted speech data is uploaded to the cloud server for storage, and meanwhile the Mel frequency cepstrum coefficient (MFCC) features of original speech are extracted as the input of the convolutional neural network (CNN) to execute the deep semantic feature extraction, which is taken as the speech keywords. Finally, the extracted speech keywords are encrypted and stored in the cloud. When the authorized user sends a retrieval request, the trained CNN is utilized to extract the keywords of the speech to be retrieved, and the search trapdoor is generated and sent to the cloud server. In the process of retrieval, the Euclidean distance is used to match the encrypted keywords with the search trapdoor. The theoretical analysis and experimental results show that the proposed scheme has higher security and retrieval accuracy, and can be suitable for the encrypted storage of speech data and efficient secure retrieval. [ABSTRACT FROM AUTHOR]

Since the powerful storage capacity of the cloud platform, more and more people are willing to store their files on the cloud service provider (CSP). In order to prevent the privacy of outsourced files from being leaked, data owners will encrypt files before uploading. However, encryption will significantly limit the accurate location of the files. Therefore, this paper mainly introduces a verifiable multi-keyword searchable encryption scheme supporting keywords updating (VMSE). First of all, our proposed VMSE scheme can achieve multiple keywords search while protecting the privacy of the outsourced files and users. Then, our VMSE scheme can also implement the integrity verification and decryption of search results, which are not considered in many existing multi-keyword searchable encryption schemes. Currently, the dynamics in search schemes mostly refer to the dynamic update of outsourced files or user's search permissions. We consider the keyword dynamic update of outsourced files in this paper, which is a design challenge for searchable encryption schemes and achieved by few searchable encryption schemes. Finally, performance evaluation shows our scheme is efficient and feasible in practical application. [ABSTRACT FROM AUTHOR]

• Flexible and selective sharing of encrypted documents among authorized users in multi-user searchable encryption. • Secure sharing of data at document level as well as keyword search by multiple users without shared keys or trusted third parties. • Efficient user revocation. • Collusion resistance against malicious users and cloud provider. Searchable encryption schemes enable secure sharing and efficient retrieval of encrypted documents stored in the cloud. Multi-user symmetric searchable encryption allows multiple users to upload encrypted data to the cloud and selectively authorize other people to search and retrieve documents without revealing any information about either the search query or sensitive information. This however, poses major challenges since it involves managing the access control policies of a set of users by a third party. Selectively sharing files among an arbitrary set of users is more challenging than allowing all members of a group to access a set of documents. The proposed scheme ensures that the search returns only those documents that are accessible to the querier and guarantees that only authorized users are allowed to decrypt a document. A bilinear map accumulator combined with pairing based cryptography ensures that only authorized users can decrypt a shared document. Prior schemes have addressed the problem using shared keys or by using trusted third parties. The proposed scheme supports both keyword searches and selective sharing of data among multiple users in the cloud without requiring shared keys or trusted third parties. The security of our scheme is proved using rigorous security analysis. [ABSTRACT FROM AUTHOR]

In the digitalized modern world in parallel to the new technological developments, information security has become the highest priority in the individual and institutional sense. In order to ensure the security of information systems, various systems are used techniques and technologies, including encryption, authorization, firewall, honeypot based systems. In this study, a honeypot based approach for intrusion detection/prevention systems (ID/PS) is proposed. The developed honeypot server application is combined with IDSs to analyze data in real-time and to operate effectively. Moreover, by associating the advantages of low and high-interaction honeypots, a superior hybrid honeypot system is performed. Therefore, in order to reduce the cost of configuration, maintenance, and management, after viewing the usage of honeypots on corporate networks, virtualization technologies are used. The developed system is a honeypot based intrusion detection and prevention system (IDPS) type and it is able to show the network traffic on servers visually in real-time animation. Thereby, it provides system information easily. Finally, the developed system can detect zero-day attack due to the configuration of intrusion detection, which makes it superior in performance compared to other IDSs. This system also helps in reducing the false positive level in IDSs. [ABSTRACT FROM AUTHOR]

Steganalysis and steganography are the two different sides of the same coin. Steganography tries to hide messages in plain sight while steganalysis tries to detect their existence or even more to retrieve the embedded data. Both steganography and steganalysis received a great deal of attention, especially from law enforcement. While cryptography in many countries is being outlawed or limited, cyber criminals or even terrorists are extensively using steganography to avoid being arrested with encrypted incriminating material in their possession. Therefore, understanding the ways that messages can be embedded in a digital medium –in most cases in digital images-, and knowledge of state of the art methods to detect hidden information, is essential in exposing criminal activity. Digital image steganography is growing in use and application. Many powerful and robust methods of steganography and steganalysis have been presented in the literature over the last few years. In this literature review, we will discuss and present various steganalysis techniques – from earlier ones to state of the art- used for detection of hidden data embedded in digital images using various steganography techniques. [ABSTRACT FROM AUTHOR]

In recent days, there is a high demand of encryption of multiple digital images for secure transmission of multiple images. This paper proposes a multi-level permutation operation based secure multiple colour image encryption technique which is totally different than the currently used multiple image encryption techniques. The proposed encryption technique uses three levels of permutation operation: the first level of permutation operation performs pixel-shuffling operations in R, G, and B components, itself; the second level of permutation operation performs row-shuffling operations in between the pixel-shuffled R, G, and B components; the third level of permutation operation performs column-shuffling operations in between the row-shuffled components. At last, the proposed encryption algorithm performs block-diffusion operations to get the final encrypted images. Multi-level permutation operations and diffusion operation only use PWLCM systems multiple times to make the algorithm more secure and stronger. Multiple PWLCM systems in multi-level permutation operations not only produces larger key space and higher key sensitivity but also generates greater randomness of pixels and weaker correlation of adjacent pixels in images as compared to the currently used multiple image encryption techniques. In addition the secret keys which are used in this proposed algorithm not only depends on the original key values but also depends on the original colour images. This protects the algorithm against known-plaintext attack and chosen-plaintext attack. The simulation results and the security analysis indicate that the proposed algorithm has good encryption results, large secret-key space, higher sensitivity towards secret keys and the plaintext, weaker correlation of adjacent pixels, greater randomness of pixels, and enough resistance against various common attacks. [ABSTRACT FROM AUTHOR]

Searchable symmetric encryption (SSE) allows one to outsource a collection of encrypted documents to a remote server, and later conduct keyword searches on these encrypted documents, while revealing minimal information to the server. Most existing SSE schemes are only proved adaptively secure against the untrusted server in the random oracle model. To enhance security, we consider the security in the standard model when designing an SSE scheme. We extend the OXT protocol of Cash et al. to support arbitrary boolean query in multi-client setting while achieving update of documents. Our scheme realizes access control on documents without requiring per-query interaction between the data owner and each client. In addition, we give a new effective T-set instantiation, which supports update of the index files. Besides, our scheme achieves provable security against adaptive adversarial server and malicious clients in the standard model. Finally, performance analysis shows the applicability of our scheme. [ABSTRACT FROM AUTHOR]

Secure transmission of multimedia contents is computationally challenging due to the sheer volume of data involved, and achieving this by fully encrypting multimedia contents is not a viable solution for mobile devices, as they run on limited battery power and employ relatively slower processors compared to their desktop counterparts. Also, in some particular application scenarios, the value, secrecy, and/or privacy of the information is time dependent and short lived. This paper presents a highly scalable approach for securing multimedia streams on mobile devices by encrypting intelligently only selected portions of the bit stream. More importantly, the proposed solution works mainly on compressed bit stream and does not require any media decoding. It encrypts on the average less than 3% of a packet load and provides robust security equivalent to that of a fully encrypted bit stream. This solution has been implemented on desktop, laptop, netbook and Nokia N series platforms. The proposed scheme is approximately 15 times faster (on average) and processes 8 to 12 times more information for a given battery life when compared to a state of the art full encryption based solutions. [ABSTRACT FROM AUTHOR]

Nowadays, the Security Information and Event Management (SIEM) systems take on great relevance in handling security issues for critical infrastructures as Internet Service Providers. Basically, a SIEM has two main functions: ((i) the collection and the aggregation of log data and security information from disparate network devices (routers, firewalls, intrusion detection systems, ad hoc probes and others) and ((ii) the analysis of the gathered data by implementing a set of correlation rules aimed at detecting potential suspicious events as the presence of encrypted real-time traffic. In the present work, the authors propose an enhanced implementation of a SIEM where a particular focus is given to the detection of encrypted Skype traffic by using an ad-hoc developed enhanced probe (ESkyPRO) conveniently governed by the SIEM itself. Such enhanced probe, able to interact with an agent counterpart deployed into the SIEM platform, is designed by exploiting some machine learning concepts. The main purpose of the proposed ad-hoc SIEM is to correlate the information received by ESkyPRO and other types of data obtained by an Intrusion Detection System (IDS) probe in order to make the encrypted Skype traffic detection as accurate as possible. [ABSTRACT FROM AUTHOR]

Quantum key distribution (QKD) has been proved superior over classical encryption techniques due to its unconditional security. Yet it remains vulnerable due to imperfect real system implementations. It is observed that decoy state method overcome the photon number splitting attack and additionally improves performance of QKD. This paper investigates a model for Decoy state QKD protocol, which ensures enhanced secret key rates and secure distance. Typically a two-state (vacuum + very weak coherent state) decoy QKD protocol with global lower bound equation for privacy amplification is analyzed. The model is tested with sets of experimental parameters and verified for its optimum performance. It is observed that global lower bound equation for privacy amplification improves secret key rates significantly. [ABSTRACT FROM AUTHOR]

• Presented cryptosystem provide multi-layered security to color image data. • Proposed scheme has higher efficiency due to realty preserving nature of algorithm. • Encrypted color image data cannot be decrypted even after applying exact keys, because proposed cryptosystem also depends on correct arrangement of parameters. The security system for RGB image information is very critical issue in current time. In this security system, we have proposed an algorithm for encryption and decryption of RGB images by using chaotic system based scrambling combined with reality preserving two dimensional discrete fractional Fourier transform (RP2DFRFT) and Arnold transform (AT). Earlier developed security system for RGB image data provides only one layer of protection either in time domain or in frequency domain. But presented cryptosystem provides multi-layer security for RGB image in time as well as in frequency domain with no loss of any information of red (R), green (G) and blue (B) components. The algorithms of existing techniques for the security of color images are mostly based on keys, but the proposed cryptosystem provides security of color images on the basis of the keys as well as the arrangement of used algorithms and parameters. Additionally, the use of reality preserving method not just eliminates the complexity of dealing with imaginary data, but it also enhances the efficiency of the technique by reducing the domain space to its half, at least for all the calculations involved in two dimensional DFRFT. The sensitivity analysis of the proposed technique represents that the encryption keys are very sensitive. Results on standard examples and their security and statistical analysis for color images are testimony to the robustness and appropriateness of the presented technique. This method would find a large applications in digital color image processing and security of color image transmission in open network. [ABSTRACT FROM AUTHOR]

Hierarchical Identity Based Encryption (HIBE) enhances the scalability of Identity based encryption scheme, by sharing the workload of the root Private Key Generator (PKG) among multiple lower-level PKGs, facilitating intermediate key escrows and private key delegation. Owing to its structure, HIBE can be deployed to provide access control in cloud, pervasive computing systems, wireless sensor networks and Massively Multiplayer Online Role-Playing Games (MMORPGs). Additionally, HIBE can be used to perform search on encrypted data, forward secure encryption, fully private communication, limited delegation and damage control. This paper evaluates different approaches in the construction of HIBE protocols to determine practical frameworks. Specific criterions like cryptographic proof models, tightness of the reduction, recipient anonymity, hardness assumptions, bounded depth, revocability, types of pairing and ciphertext indistinguishability properties, were used as benchmarks for assessing each scheme. The efficiency in terms of storage and computation overhead, was estimated to identify suitable protocols for securing different computing environments. The future prospective applications of HIBE protocols were also investigated. [ABSTRACT FROM AUTHOR]

Clustering can be made effective in CEAACK MANETs by opting for a cluster head mechanism which ensures that control rests with a single powerful node within a cluster. This cluster head takes on the responsibility of routing the packets efficiently by coordinating with the base station. Generally route maintenance and route discovery is a very important mechanism for maintaining route life. In route discovery, a flooding scheme is usually used to send and receive the route request and route reply message. Based on the route discovery, the routing methods are categorized into Proactive and Reactive methods. Reactive Routing Protocol is also called On Demand Routing Protocol like AODV (AdHoc on Demand Vector Routing) and DSR (Dynamic Source Routing) and they can improve the scalability of CEAACK MANETs by limiting the routing overhead when a new route is requested. However, due to node mobility in CEAACK MANETs, frequent link breakages may lead to frequent path failures and route discoveries, which could increase the overhead of routing protocols and reduce the packet delivery ratio and increases the end-to-end delay. We propose a novel protocol which provides an efficient route discovery technique along with a competent Three Fish algorithm. This is based on understanding the neighbouring clusters and efficiently using this information to reduce the routing overhead in CEAACK MANETs. The proposed protocol is used to determine the forwarding order and exploit the neighbour coverage knowledge more effectively. The novel distributed routing protocol guarantees security, anonymity and high reliability of the established route in a hostile environment, such as an ad hoc wireless network, by encrypting the routing packet header and abstaining from using unreliable intermediate nodes. The major objective of our protocol is to allow trustworthy intermediate nodes to participate in the path construction protocol without jeopardizing the anonymity of the communicating nodes. An enhanced three fish Algorithm is used to ensure the safety of the data during a transmission by using a unique key during the encryption and decryption process. We describe our protocol, STFDR (Secure Three Fish Distributed Routing), and provide its proof of correctness. [ABSTRACT FROM AUTHOR]

As the importance of personal data privacy increases, traffic encryption has become an important topic in network communication. In the field of network security and management, the development of encrypted traffic classification technology has drawn attention to deep learning methods. For raw encrypted traffic, deep learning models can realize end-to-end classification with high accuracy. However, deep learning methods do not explain which part of the encrypted traffic is critical to classification, and that will limit their application in some cyber security scenarios that demand high interpretability. The approach proposed in this paper features a novel feature engineering method named "BITization" to determine the encoding method of features and a sliding window technique to explore which bytes contribute the most to the classification. The accuracy of classical machine learning methods in encrypted traffic is improved by at least 14.1% through the proposed feature engineering approach. In the experiments, the enhanced methods achieve a 98.6% average accuracy and a 98.5% average F1-score on the ISCX-VPN-Service, Cross-Platform-IOS, Cross-Platform-Android, and USTC-TFC2016 datasets, from which we believe a state-of-the-art performance is achieved. [ABSTRACT FROM AUTHOR]

Quantum fully homomorphic encryption (QFHE) allows arbitrary computations which is performed by each server on encrypted quantum states without decrypting them. However, the existing QFHE schemes are not capable to handle the volatility problem with the servers: once a dynamic server wants to leave or join the protocol, it must be updated. Consequently, a dynamic quantum fully homomorphic encryption (DQFHE) scheme based on universal quantum circuit (UQC) is proposed in this paper. Firstly, our scheme could extend the two-part QFHE scheme to m-part. Secondly, the dynamic property means the completed protocol could be retained when involved servers changed which means we allow new servers to join our scheme and the absence of elder servers. Thirdly, UQC enables arbitrary quantum transformations on the encrypted quantum states and could be proved to be perfectly secure, and the key-updating algorithms are also based on the UQC so that the keys could not be revealed. Finally, due to the property of QFHE, compared with the quantum secret sharing, we could finish the sharing procedure efficiently because we cancel the security check procedure. [ABSTRACT FROM AUTHOR]

We introduce a new cryptographic primitive called public key encryption with public-verifiable decryption delegation (PKE - PV D 2 ), that enables the original decryptor to transmit the decryption key for a specific ciphertext to a designated recipient in a way that is both public-verifiable and privacy-preserving. Because of its ability to delegate public-verifiable and ciphertext-level decryption, it is useful in scenarios that require special decryption delegation, such as when the court needs to retrieve a specific message from the ciphertext as significant judgment evidence. Moreover, we present the first PKE - PV D 2 scheme and its corresponding security proof in the random oracle model, using bilinear pairing. Additionally, we provide a prototype of our proposal, and our extensive experimental results demonstrate its effectiveness and efficiency. [ABSTRACT FROM AUTHOR]

• The proposed algorithm solves the problem of not taking both robustness and lossless. • The encryption part is an mechanism that is universal to the encryption algorithm. • The algorithm is suitable for vector data with similar structure, such as CAD. As an organic integration of encryption and watermarking technology, commutative encryption and watermarking (CEW) overcomes the limitation that a single security protection technology cannot provide full-process data protection. Existing CEW algorithms for vector geographic data, however, only take attack robustness into account, making them inappropriate for copyright protection of high-precision vector geographic data since the influence of embedding watermark on data accuracy. This study presents a CEW algorithm that utilizes geometric features and the initial vertex order of features to address this issue. The minimum bounding rectangle (MBR) is chosen as the geometric characteristic in this method to provide independent operating space for watermark and encryption. The encryption is completed by randomly shifting the coordinates of the features. At the same time, the watermark information is embedded by modifying the features' starting vertex order. The watermark can be extracted either from the plaintext or the ciphertext, as the order of the element's starting points remains unchanged regardless of the coordinates. Finally, the commutative, robustness, and lossless ness of the algorithm in this study are experimentally validated. As can be demonstrated by the results, the proposed algorithm is more robust, lossless, and secure than some state-of-the-art algorithms. [ABSTRACT FROM AUTHOR]

To solve the problems of low efficiency, inflexible updates and the high storage cost of existing result verifiable searchable encryption schemes, we propose a dynamic searchable encryption scheme with block verification using redactable blockchain. First, the inverted index is divided into blocks, the verification tag corresponding to the block index is uploaded to the redactable blockchain, and smart contracts are used to perform block verification of the query results to improve the query and verification performance. Furthermore, we use the blockchain rewriting technology to update the tags in the result checklist, improving the data update performance and scalability of the blockchain, and ensuring the constant storage overhead of the blockchain. Security analysis confirms that our proposals guarantee the correctness and completeness of the query results. Experimental results show that our proposed approach can improve the query efficiency and result verification efficiency under the premise of the low-speed growth of the blockchain data scale. In particular, the advantages become more significant as the data collection scale grows. • Result verifiability along with support to block verification based on redactable blockchain. • Block indexes enables parallel search and only affect a constant amount of data during the update. • Block verification without the additional storage-computational overhead. • Redactable technology realizes the rewritable storage of avoiding the waste of block resources. [ABSTRACT FROM AUTHOR]

• We apply T-SNE, to reduce the multi-dimensional of a dataset and generate similar keyword document groups. The similar documents group idea is apply adopted with coordinate matching combined TF-IDF rule by constructing an innovative inverted index for ranked keywords search over outsourced encrypted data. • The proposed method applies a role-based range polynomial access control mechanism. This improves search results security and realizes accurate multi keywords search for top-k documents retrieval over encrypted data. • To support efficient secure privacy-preserving multi keywords rank search access control with correctness search result verification. We apply real HMAC techniques to generate an authentication tag for each record in the searchable index. The authentication tag can be regularly updated when a search index update occurs. Which avoid the cloud server to access the old data that has been essentially updated. • We provide a details analysis of the privacy, security, verifiability, and efficiency of the SPMRS scheme. The experimental result conduct and performance work compared to existing schemes shows that our scheme is high search efficiency. Verifiable multi keywords rank searchable encryption is an important technique to retrieve encrypted data in a cloud server and verify the validity of search results. The cloud server is malicious it may return incorrect search results or system fault. Thus, how to design verifiable secure multi keywords ranked search of outsourced encrypted data is an unsolved problem. Therefore, in this paper, we leverage the (T-SNE) techniques to reduce dimensionality and feathers transformation. Then adopt similar keywords clustering groups grouping strategy to construct an enhanced inverted index. Which links to coordinate matching techniques to improve accurate multi-keyword rank searches for practical user experience. Then Paillier Homorphic Encryption (P.H.E) and HMAC technique is adopted for search index encryption and keyword search verification to explore verifiable multi keywords rank search over encrypted data in the cloud server. The time cost of ranking score computation and search efficiency can be improved in two approaches, keywords grouping idea and no dummy keywords are added in query and documents vector. Thus, our scheme realizes verifiable multi keywords search exact ciphertext retrieval. We evaluated the performance of our proposed scheme using real-world datasets that ensure adequate security and privacy. [ABSTRACT FROM AUTHOR]

The cloud computing technology is a novel storage and computing paradigm that enables individuals and organizations to store data, share data with intended group of users and retrieve data when require. It greatly improves peoples' data storage and sharing, and data retrieval capabilities by providing flexible, less expensive and quality services. For data security and privacy concerns, secure and authenticated data storage, fine-grained access control of encrypted data, secure search for the outsourced data and search results verification are of critical importance. However, achieving the aforementioned functionalities simultaneously is quite challenging. In this paper, for the first time, we propose a secure lightweight Attribute-Based verifiable Data Storage and data Retrieval Scheme (ABDSRS) for cloud environments that attains the following features: (i) lightweight design, (ii) provably secure, (iii) fine-grained data access control, (iv) data owner (DO) anonymity, (v) data and DO authenticity, (vi) keyword policy search over encrypted data, (vii) keyword privacy, and (viii) search results verification. ABDSRS employs attribute-based online-offline mechanism in which only authorized DOs can anonymously upload data to the cloud. And, a data user (DU) can search over encrypted data using keyword policy. ABDSRS enables a DU to verify the correctness of the search results (i.e., the correctness of the operations performed by the cloud) without interacting with any authority. ABDSRS is lightweight in the sense that the heavy computations are offloaded either to the cloud or to offline phase, while only lightweight operations are executed at the DU device. We formalize more general security definitions of ABDSRS by considering various possible adversarial capabilities and present rigorous security analysis. We also conduct experiments to evaluate ABDSRS's performance. [ABSTRACT FROM AUTHOR]

• The system supports secure keyword searches among different keys. • The public key-based searchable encryption achieves sublinear search complexity. • The search system is highly extensible for owner and user updates. • The expired key is invalidated by an efficient key revocation mechanism. • The search system resists collusion between some users and the cloud server. Searchable encryption (SE) is a promising technology that provides search functions while preserving information privacy. A small number of SE schemes can be applied to a distributed system. In such systems, multiple owners provide data that is encrypted by their secret keys to the system for retrieval by users. In this setup, however, users need to scan a searchable index for retrievals, which leads to linear search complexity. Moreover, updates of users (e.g., revoking an expired user from the system) generally incur substantial overhead to re-build the index. Accordingly, we propose a scan-free verifiable public-key searchable encryption scheme with an efficient user update function in a distributed system (i.e., in a multi-owner multi-user model). First, owners self-select secret keys to encrypt keywords. A master secret key is designed to support keyword searches among these keys. Additionally, a searchable index with an implicit relationship between the same keyword is proposed. There is no need to scan the index for keyword retrieval, which achieves sub-linear search complexity. It is also important that the updates of owners do not exert an influence on users and the other owners in our proposed scheme. As the key revocation mechanism, the master secret key is split into more partial secret keys that are distributed to users. Accordingly, the system only needs to re-split and re-distribute the key rather than re-building the index for updates of users. When making queries, not only are the content of queries and the master secret key concealed, but collusion between some users and the cloud server is resisted. The proposed scheme also supports an efficient result verification mechanism. The security and utility of our scheme were confirmed thru analysis and evaluation. [ABSTRACT FROM AUTHOR]

As the world grapples with the COVID-19 and its variants, multi-user collaboration by means of cloud computing is ubiquitous. How to make better use of cloud resources while preventing user privacy leakage has become particularly important. Multi-key homomorphic encryption(MKHE) can effectively deal with the privacy disclosure issue during the multi-user collaboration in the cloud computing setting. Firstly, we improve the DGHV homomorphic scheme by modifying the selection of key and the coefficients in encryption, so as to eliminate the restriction on the parity of the ciphertext modulus in the public key. On this basis, we further propose a DGHV-type MKHE scheme based on the number theory. In our scheme, an extended key is introduced for ciphertext extension, and we prove that it is efficient in performance analysis. The semantic security of our schemes is proved under the assumption of error-free approximate greatest common divisor and the difficulty of large integer factorization. Furthermore, the simulation experiments show the availability and computational efficiency of our MKHE scheme. Therefore, our scheme is suitable for the multi-user scenario in cloud environment. [ABSTRACT FROM AUTHOR]