Search

For more than two decades, proving or refuting the following statement has remained a challenging open problem in the theory of secret sharing schemes (SSSs): every ideal access structure admits an ideal perfect multi-linear SSS. The class of group-characterizable (GC) SSSs include the multi-linear ones. Hence, if the above statement is true, then so is the following weaker statement: every ideal access structure admits an ideal perfect GC SSS. One contribution of this paper is to show that ideal SSSs are not necessarily GC. Our second contribution is to study the above two statements with respect to several variations of weakly-ideal access structures. Recently, Mejia and Montoya studied ideal access structures that admit ideal multi-linear schemes and provided a classification-like theorem for them. We additionally present some tools that are useful to extend their result.

Numerous research efforts have been proposed for efficient processing of range queries in high-dimensional space by either redesigning R-tree access structure for exploring massive parallelism on single GPU or exploring distributed framework of R-tree. However, none of the existing efforts explores the integration of the parallelization of the R-tree on a single GPU with a distributed framework for the R-tree. The problem of designing an efficient multi-GPU indexing method, which can effectively combine the parallelism maximization with distributed processing of the R-tree, remains an open challenge. In this paper, we present a novel multi-GPU efficient parallel and distributed indexing method, called LBPG-tree. The rationale of the LBPG-tree is to combine the advantages of an instruction pipeline in CPU with the massive parallel processing potential of multiple GPUs by introducing two new optimization strategies: First, we exploit the GPU L2 cache for accelerating both index search and index node access on GPUs. Second, we further improve utilization of L2 cache on GPUs by compacting and sorting candidate nodes called Compact-and-Sort. Our experimental results show that the LBPG-tree outperforms G-tree, the previous representative GPU index method and effectively support multiple GPUs for providing efficient high dimensional range query service.

As the public cloud becomes one of the leading ways in data sharing nowadays, data confidentiality and user privacy are increasingly critical. Partially policy-hidden ciphertext policy attribute-based encryption (CP-ABE) can effectively protect data confidentiality while reducing privacy leakage by hiding part of the access structure. However, it cannot satisfy the need of data sharing in the public cloud with complex users and large amounts of data, both in terms of less expressive access structures and limited granularity of policy hiding. Moreover, the verification of access right to shared data and correctness of decryption are ignored or conducted by an untrusted third party, and the prime-order groups are seldom considered in the expressive policy-hidden schemes. This paper proposes a fully policy-hidden CP-ABE scheme constructed on LSSS access structure and prime-order groups for public cloud data sharing. To help users decrypt, HVE with a “convert step” is applied, which is more compatible with CP-ABE. Meanwhile, decentralized credible verification of access right to shared data and correctness of decryption based on blockchain are also provided. We prove the security of our scheme rigorously and compare the scheme with others comprehensively. The results show that our scheme performs better.

Mobile healthcare (mHealth) enables people to collect and share their personal health records (PHRs) and gain rapid medical treatment via mobile 5G-enabled Industrial Internet of Things (IIoT) devices, which also brings the challenge of keeping the PHRs confidentiality and preventing unauthorized access. By the emerging Ciphertext-Policy Attribute-based Encryption (CP-ABE), the PHR owner can encrypt his PHR data under self-defined access policies. However, existing CP-ABE schemes are suffering from either heavy computation cost and storage overhead or traitor tracing and direct revocation. In this paper, we propose an efficient, traceable and revocable access control scheme named TRAC for mHealth in 5G-enabled IIoT. In TRAC, the ciphertext is composed of the attribute-relevant ciphertext encrypted under an AND-gate access structure and the identity-relevant ciphertext associated with some potential receivers. The malicious user who leaks his/her privilege to unauthorized entities will be precisely tracked and added in the revocation list, by which the cloud server can update the identity-relevant ciphertext by itself. The length of final ciphertext and the time of bilinear pairing operations used in decryption are constant. The security analysis and performance evaluation indicate the security, efficiency and practicality of TRAC.

Existing attribute-based encryption schemes with revocation to secure the cloud-assisted internet of things (IoTs) raise challenges such as eliminating the need for predefined public parameters in system initialization, performing the encryption and decryption operations efficiently and achieving adaptive security under standard security assumption. In this paper, we addresses these challenges by proposing an unbounded and efficient revocable attribute-based encryption scheme with adaptive security for cloud-assisted IoTs. Distinct from the previous approaches in this field, our scheme not only efficiently realizes access control over encrypted data in a fine-grained and revocable way, but also is proved to be adaptively secure under standard decision linear assumption. Meanwhile, the parameters don’t need to be pre-defined in the system initialization and thus our scheme satisfies the unbounded property. Moreover, the monotonic span program (MSP) is elegantly utilized as the access structure to reduce the number of bilinear pairing and exponentiation operations for encryption and decryption. Theoretical performance analysis and experiment evaluation disclose that our proposed scheme owns outstanding feasibility, efficiency, and effectiveness.

Multipartite secret sharing schemes are those having a multipartite access structure, in which the set of participants is divided into several parts and all participants in the same part play an equivalent role. Secret sharing schemes for multipartite access structures have received considerable attention due to the fact that multipartite secret sharing can be seen as a natural and useful generalization of threshold secret sharing.

Becoming a vital position in the interconnection industry of the Internet of Things, IIoT has promoted the conversion of traditional industries to intelligent industries. However, it is necessary further to solve the security and privacy threats in IIoT while reducing communication bandwidth and computing resource consumption to carry out research. In order to solve the problem of user privacy leakage caused by the access structure, a fog computing-oriented access control structure hiding scheme is proposed in the paper. The Paillier homomorphic filter algorithm is introduced in the fog calculation. The Paillier homomorphic algorithm hides the mapping function in the access structure during the data upload process, achieving the effect of completely hiding the access structure. Moreover, the ciphertext is stored separately from the access structure, and the Paillier homomorphic algorithm is run through the fog node during the decryption process to detect whether the attributes of the data user exist in the hidden access structure. If it exists, reconstruct the mapping function and send it to the data user, who then downloads and decrypts the ciphertext. If it does not exist, it means that the data user does not meet the access conditions of the data, and there is no need to download and decrypt the ciphertext. Meanwhile, a simulation experiment platform is constructed in the paper to distinguish the performance of the method proposed in the paper from other similar methods, proving the efficiency and practicability of the scheme.

Existing block-based progressive visual cryptography schemes (BPVCS) that prevent cheating are limited to ( 2 , n ) and ( k , n ) thresholds. They are unsuitable for implementing complex sharing techniques in the actual world. A cheating immune BPVCS for general access structure (GAS) is proposed in this paper. To find the parameters that make up the proposed scheme, a simplified multiple assignment procedure based on integer linear programming is introduced. The secret parts can be decrypted by the members of a qualified set. Participants in a forbidden set, on the other hand, are not allowed to know about the secret. The proposed scheme includes cheat-prevention and progressive recovery capabilities. In addition, to generate meaningful shadows for BPVCS, a modified extended VCS (EVCS) is proposed. Our modified EVCS can solve the cover-interference problem in conventional BPVCS. The effectiveness and benefits of the proposed BPVCS are supported through the experimental findings and comparisons.

Data sharing has become a key technology to break down data silos in the big data era. Ciphertext-policy attribute-based encryption (CP-ABE) is widely used in secure data-sharing schemes to realize flexible and fine-grained access control. However, in traditional CP-ABE schemes, the access structure is directly shared along with the ciphertext, potentially leading to users’ private information leakage. Outsourcing data to a centralized third party can easily result in privacy leakage and single-point bottlenecks, and the lack of transparency in data storage and sharing casts doubts whether users’ data are safe. To address these issues, we propose a blockchain-based CP-ABE scheme with partially hidden access structures (BCP-ABE-PHAS) to achieve fine-grained access control while ensuring user privacy. First, we propose an efficient CP-ABE scheme with partially hidden access structures, where the ciphertext size is constant. To assist data decryption, we design a garbled Bloom filter to help users quickly locate the position of wildcards in the access structure. Then, to improve storage efficiency and system scalability, we propose a data storage scheme that combines blockchain technology and the interplanetary file system, ensuring data integrity. Finally, we employ smart contracts for a transparent data storage and sharing process without third-party participation. Security analysis and performance evaluation show that the proposed BCP-ABE-PHAS scheme can preserve policy privacy with efficient storage and low computational overhead.

Secret sharing is an important concept in cryptography, however it is a difficult problem to determine the access structure of the secret sharing scheme based on a linear code. In this work, we construct two-weight linear codes over finite field by using linear codes over finite ring. We first study MacDonald codes over the finite ring $\mathbb{F}_2$+v$\mathbb{F}_2$+v2$\mathbb{F}_2$ with v3=v. Then we give torsion codes of MacDonald codes of type α and β, which are two-weight linear codes. Finally we give the access structures of secret sharing schemes based on the dual codes of the two-weight codes.

Proxy re-encryption is an essential prerequisite that facilitates a foreign entity (e.g., cloud server) to enforce the access of provisions of a document extended by one user to another user. While...

With the rapid development of cloud computing, the ensuing security issues have become increasingly prominent. In this context, attribute-based encryption (ABE) has gradually attracted widespread attentions due to its unique attribute matching mechanism. At the same time, mobile devices have put forward higher requirements for the design and deployment of ABE schemes. Therefore, in this paper, we propose an original hybrid cloud multi-authority ciphertext-policy attribute-based encryption (HCMACP-ABE) scheme. Specifically, we utilize the LSSS (Linear Secret-Sharing Schemes) access structure to realize secure access control, while the private cloud is responsible for maintaining the user’s authorization list and verifying the user. Finally, we prove that our proposal achieves IND-CCA secure and is efficient in a mobile hybrid cloud environment.

Multipartite secret sharing schemes are those that have multipartite access structures. The set of the participants in those schemes is divided into several parts, and all the participants in the same part play the equivalent role. One type of such access structure is the compartmented access structure, and the other is the hierarchical access structure. We propose an efficient compartmented multisecret sharing scheme based on the linear homogeneous recurrence (LHR) relations. In the construction phase, the shared secrets are hidden in some terms of the linear homogeneous recurrence sequence. In the recovery phase, the shared secrets are obtained by solving those terms in which the shared secrets are hidden. When the global threshold is t , our scheme can reduce the computational complexity of the compartmented secret sharing schemes from the exponential time to polynomial time. The security of the proposed scheme is based on Shamir’s threshold scheme, i.e., our scheme is perfect and ideal. Moreover, it is efficient to share the multisecret and to change the shared secrets in the proposed scheme.

XOR-based Visual Cryptography System (XVCS) is developed to achieve high contrast and good resolution of the recovered secret image. In general (k,n) VCS, the secret image can be visualized only if k or more than k shares are stacked together. In (k,n,t)∗ access structure, t number of participants are considered as the essential participants(t ≤ k ≤ n) whose shares are absolutely necessary to reconstruct the secret image. Several methods have been already proposed for the construction of (k,n)∗ VCS for black and white images. The major focus of this work is to design an XVCS for (k,n,t)∗ access structure for both black and white images and color images with maximum contrast. The experimental outcome shows that the proposed method has better results than other techniques proposed so far. Also, numerical examples are provided for (k,n,t)∗ XVCS for t = 1 and 2. The XVCS designed for (k,n,t)∗ access structure can be used for any real time application and is demonstrated with an example of user authentication in banking system.

In 1992, Frankel and Desmedt introduced a technique that enables one to reduce the secret space of an ideal homomorphic secret sharing scheme (IHSSS) into any of its characteristic subgroups. In this paper, we propose a similar technique to reduce the secret space of IHSSSs called the quotient technique. By using the quotient technique, we show that it is possible to yield an ideal linear scheme from an IHSSS for the same access structure, providing an alternative proof of a recent result by Jafari and Khazaei. Moreover, we introduce the concept of decomposition of secret sharing schemes. We give a decomposition for IHSSSs, and as an application, we present a necessary and sufficient condition for an IHSSS to be mixed-linear. Continuing this line of research, we explore the decomposability of some other scheme classes.

Attribute-based encryption (ABE) provides a fine-grained access control mode for multiuser network environments. The popularity of 5th generation (5G) mobile network applications has greatly increased the data transmission rate, but mobile terminal devices with limited resources in the network have difficulty with the high computational overhead of ABE in wireless communication. In response to this problem, this paper proposes a hybrid encryption online/offline ciphertext policy attribute-based encryption (CP-ABE) scheme for 5G. In the scheme, the data owner uses symmetric encryption technology to perform data encapsulation on plaintext and outsources the encapsulated plaintext to the cloud user assistant (CUA) for offline calculation. Key encapsulation is performed on a symmetric key to form the final ciphertext, and it is uploaded to the cloud server. After the data user obtains the ciphertext, it is handed over to the CUA for offline decryption calculation. If the access structure is satisfied, the encapsulated ciphertext can be obtained, and then the symmetric key is used to decrypt the ciphertext. In the scheme, the correctness of the symmetric key can be verified to prevent malicious tampering in the process of transmission. It is indicated that the scheme is secure after being tested with the decisional q-Parallel Bilinear Diffie-Hellman Exponent (BDHE). Numerical analysis shows that the scheme has decreased computational overhead and can achieve fine-grained access control of user decryption rights.

With the development of cloud computing application, attribute-based encryption (ABE) with flexibly fine-grained data access control is widely adopted. However, traditional data access structures are mainly constructed on independent and fixed attribute values. The data access policies in traditional ABE schemes don’t express the relationship of different attributes and the dynamic attribute values. Those seriously restrict wider application of ABE techonlogy. To resolve the problem, condition expression (CE) is first adopted to describe the demanded condition of attribute variables, which also includes combination operation related to many different attribute variables. A rule of CE is established to generate a concreted CE with unique form for an attribute condition. A running function of CE is presented to judge whether the related attribute values satisfy the specified CE automatically. In this article, we provide a ciphertext-policy ABE scheme which adopts the and-gate multi-value attribute access structure with additional CE (and-gate-CE), which has constant ciphertext length and can be proven CPA-secure under the decision q-BDHE assumption in random oracle model. Our scheme realizes to provide a more general data access policy with complicated and flexible CE in and-gate multi-value ABE scheme.

Boolean functions play an important role in coding theory and symmetric cryptography. In this paper, three classes of Boolean functions with six-valued Walsh spectra are presented and their Walsh spectrum distributions are determined. They are derived from three classes of bent functions by complementing the values of the functions at three different points, where the bent functions are the Maiorana-McFarland types, Dillon $\mathcal {PS}_{ap}$ types and the monomial form $T{r^{n}_{1}}(\lambda x^{r(2^{m}-1)})$ , respectively. As an application, we construct some classes of binary linear codes and it turns out that these codes can be used in secret sharing schemes with interesting access structure.

Unauthorized access to location information in location-based service is one of the most critical security threats to mobile Internet. In order to solve the problem of quality of location sharing while keeping privacy preserved, adaptive privacy preserved location sharing scheme called APPLSS is proposed, which is based on a new hierarchical ciphertext-policy attribute-based encryption algorithm. In the algorithm, attribute authority sets the attribute vector according to the attribute tags of registration from the location service providers. Then the attribute vector can be adaptively transformed into an access structure to control the encryption and decryption. The APPLSS offers a natural hierarchical mechanism in protecting location information when partially sharing it in mobile networks. It allows service providers access to end user's sensitive location more flexibly, and satisfies a sufficient-but-no-more strategy. For end-users, the quality of service is obtained while no extra location privacy is leaked. To improve service response performance, outsourced decryption is deployed to avoid the bottlenecks of the service providers and location information providers. The performance analysis and experiments show that APPLSS is an efficient and practical location sharing scheme.

In recent years, attribute-based encryption (ABE) provides a new idea to help researchers solving the problem of data privacy protection in cloud. But there are two issues in traditional ABE, the first issue is that the attributes in the access structures will be sent to users in cleartext together with the ciphertext. So a attacker has the opportunity to obtain some of the private information from the plaintext access structure. And the other issue is the traditional ABE scheme cannot revoke the users' illegal keys in an efficient way. To handle both of the above challenges, we come up with a large universe ciphertext-policy ABE (CP-ABE) scheme which supports partially hidden access structures (PHAS) and highly efficient key revocation at the same time in this paper. What's more, unlike most previous schemes, first our access structure is based on the expressive linear secret sharing scheme (LSSS) which supports both AND and OR gates in access formulas and second our scheme is built from the prime-order bilinear pairing groups. The comparison with other relevant works presents that our scheme is more comprehensive and efficient. Finally we rigorously prove and analyze that our scheme is selectively indistinguishable secure under chosen plaintext attacks (IND-CPA) in the random oracle model (ROM) and our access structure is really anonymous against off-line dictionary attacks.

Due to poor traffic conditions and the high costs of traveling by private cars, ride sharing has become a popular means to trip. In view of the security threats and centralization existing in the current ride-sharing service, we propose a secure ride-sharing scheme based on a consortium blockchain, which can guarantee the security, confidentiality, and privacy of data interaction via attribute-based proxy re-encryption algorithm. First, the passenger presets the access structure and encrypts the data using attribute-based encryption. The ciphertext is then sent to the roadside unit (RSU), which broadcasts the carpooling request to the driver. After receiving the request, the driver sends the itinerary attribute to RSU, which performs carpool matching according to received ciphertext and itinerary attributes, then the ciphertext is re-encrypted and sent to the matched driver. Second, the master node uses an improved Delegated Proof-of-Stake (DPoS) consensus to verify the carpool record, which is stored on the blockchain after the verification is successful. In case of disputes, block data can be utilized for traceability. Third, drivers and passengers use the credibility mechanism to score each other after ride sharing. In addition, trusted authority can reveal the real identity of malicious users. Finally, we conduct a security analysis and performance evaluation for our proposed scheme. The results manifest that our scheme not only meets the security and privacy requirements of ride-sharing services but also effectively resists potential security risks. Therefore, our scheme is feasible, efficient, and suitable for ride-sharing services.

The policy-controlled signature (PCS) scheme uses the access policy to control signature verification permission. However public access policy that may contain private information will leak user privacy. At the same time, the expressiveness of access structures in the PCS schemes is weak. Therefore, we propose a policy-controlled signature scheme with strong expressiveness and privacy-preserving policy (PCS-PP), in which linear secret sharing schemes is to design access structure which has strong expression, the three primes composite order bilinear groups is used to hide the attribute value into the attribute name that may expose the privacy data by data distortion concept. The proposed PCS-PP scheme not only has correctness and privacy-preserving policy, but also supports fine-grained signature verification. In addition, the unforgeability is proved in the random oracle model. Compared to the related schemes, the proposed PCS-PP scheme has superiority in features, computation cost and storage.

Visual secret sharing (VSS) is a new technique for sharing a binary image into multiple shadows. For VSS, the original image can be reconstructed from the shadows in any qualified set, but cannot be reconstructed from those in any forbidden set. In most traditional VSS schemes, the shadows held by participants have the same importance. However, in practice, a certain number of shadows are given a higher importance due to the privileges of their owners. In this article, a novel ( t , s , k , n )-threshold VSS scheme is proposed based on access structure partition. First, we construct the basis matrix of the proposed ( t , s , k , n )-threshold VSS scheme by utilizing a new access structure partition method and sub-access structure merging method. Then, the secret image is shared by the basis matrix as n shadows, which are divided into s essential shadows and n - s non-essential shadows. To reconstruct the secret image, k or more shadows should be collected, which include at least t essential shadows; otherwise, no information about the secret image can be obtained. Compared with related schemes, our scheme achieves a smaller shadow size and a higher visual quality of the reconstructed image. Theoretical analysis and experiments indicate the effectiveness of the proposed scheme.

Secret sharing is an important building block in cryptography. All explicit secret sharing schemes which are known to have optimal complexity are multi-linear, thus are closely related to linear codes. The dual of such a linear scheme, in the sense of duality of linear codes, gives another scheme for the dual access structure. These schemes have the same complexity, namely the largest share size relative to the secret size is the same. It is a long-standing open problem whether this fact is true in general: the complexity of any access structure is the same as the complexity of its dual. We give a partial answer to this question. An almost perfect scheme allows negligible errors, both in the recovery and in the independence. There exists an almost perfect ideal scheme on 174 participants whose complexity is strictly smaller than that of its dual.

Edge intelligence is an emerging concept referring to processes in which data are collected and analyzed and insights are delivered close to where the data are captured in a network using a selection of advanced intelligent technologies. As a promising solution to solve the problems of insufficient computing capacity and transmission latency, the edge intelligence-empowered Internet of Vehicles (IoV) is being widely investigated in both academia and industry. However, data sharing security in edge intelligent IoV is a challenge that should be solved with priority. Although attribute-based encryption (ABE) is capable of addressing this challenge, many time-consuming modular exponential operations and bilinear pair operations as well as serial computing cause ABE to have a slow decryption speed. Consequently, it cannot address the response time requirement of edge intelligent IoV. Given this problem, an ABE model with parallel outsourced decryption for edge intelligent IoV, called ABEM-POD , is proposed. It includes a generic parallel outsourced decryption method for ABE based on Spark and MapReduce. This method is applicable to all ABE schemes with a tree access structure and can be applied to edge intelligent IoV. Any ABE scheme based on the proposed model not only supports parallel outsourced decryption but also has the same security as the original scheme. In this paper, ABEM-POD has been applied to three representative ABE schemes, and the experiments show that the proposed ABEM-POD is efficient and easy to use. This approach can significantly improve the speed of outsourced decryption to address the response time requirement for edge intelligent IoV.

Consider the following secret-sharing problem: A file s should be distributed between n servers such that (d-1)-subsets cannot recover the file, (d+1)-subsets can recover the file, and d -subsets should be able to recover s if and only if they appear in some pre-defined list L . The goal is to minimize the information ratio—that is, the number of bits stored on a server per each bit of the secret. We show that for any constant d and any pre-defined list L , if the file is sufficiently long (exponential in n d ), the problem can be solved with a constant asymptotic information ratio of c d that does not grow with the number of servers n . This result is based on a new construction of d -party conditional disclosure of secrets for arbitrary predicates over an n -size domain in which each party communicates at most four bits per secret bit. In both settings, previous results achieved a non-constant information ratio that grows asymptotically with n , even for the simpler special case of d = 2 . Moreover, our constructions yield the first example of an access structure whose amortized information ratio is constant, whereas its best-known non-amortized information ratio is sub-exponential, thus providing a unique evidence for the potential power of amortization in the context of secret sharing. Our main result applies to exponentially long secrets, and so it should be mainly viewed as a barrier against amortizable lower-bound techniques. We also show that in some natural simple cases (e.g., low-degree predicates), amortization kicks in even for quasi-polynomially long secrets. Finally, we prove some limited lower bounds and point out some limitations of existing lower-bound techniques.

We construct a new protocol for attribute-based encryption with the use of the modification of the standard secret sharing scheme. In the suggested modification of the secret sharing scheme, only one master key for each user is required that is achieved by linearly enlarging public parameters in access formula. We then use this scheme for designing an attribute-based encryption protocol related to some access structure in terms of attributes. We demonstrate that the universe of possible attributes does not affect the resulting efficiency of the scheme. The security proofs for both constructions are provided.

Various studies have focused on secret sharing schemes and in all of them, each shareholder is interested in a shorter share. The information rate of a secret sharing scheme shows the ratio between the size of the secret to the maximum number of shares given to each shareholder. In this regard, the researchers investigated the optimal information rate of the graph access structure. This paper aims to discover the exact values for the optimal information rates of the two graph access structures, which remained as open problems in Van Dijk’s paper. Furthermore, we introduced the developed multipartite graph and the developed cycle graph and calculated the exact value of their optimal information rate. Moreover, we presented a lower bound on the information rate for other developed graph access structures.

m-Health stands for mobile health, where mobile devices are used for collecting and distributing health-related data. As the information related to personal health is sensitive in nature, so it should be encrypted first before storing it at the potentially untrusted servers. However, encryption severely affects basic sharing and search operations. To address these issues, a combination of attribute-based encryption and searchable encryption is devised, which enables secure fine-grained search over encrypted data. But the resultant technique incurs high computational complexity, which makes it unsuitable for resource-constrained mobile devices. So, in order to deploy it to mobile devices, searchable encryption should generate constant size secret keys and ciphertexts. However, in existing attribute-based keyword search (ABKS) schemes, the size of the secret key and the ciphertext is proportional to the number of attributes, thus resulting in linear complexity. In this paper, we have proposed a novel ABKS scheme with constant-size secret keys and ciphertexts, thus further reducing the computational cost. Our scheme uses a ciphertext-policy (CP) design framework and supports an AND gate access structure. Further, the proposed CP-ABKS scheme can be proved secure in the selective security model under augmented multi-sequence of exponents decisional Diffie-Hellman assumption.

One of the modern applications of cryptography is the sharing of secrets in occurrence keys. Indeed, the need to establish a shared secret key in a multi-user system clearly remains a major problem of trust between users. Therefore, one solution is to share this secret key between users seamlessly. New technologies embedded systems such as sensor networks provide an ideal platform for sharing secrets. In addition, elliptic curves offer an adequate solution for reducing the size of keys, which is suitable for embedded systems. In this article, we propose an approach for sharing a secret leaked in a QR code adapted for a multiuser system, where each user has the ability to verify its share by an access structure. The system allows a recovery without loss of data in this case the QR code used.

Internet of Things (IoT) is an integration of various technologies to provide technological enhancements. To enforce access control on low power operated battery constrained devices is a challenging issue in IoT scenarios. Attribute-based encryption (ABE) has emerged as an access control mechanism to allow users to encrypt and decrypt data based on an attributes policy. However, to accommodate the expressiveness of policy for practical application scenarios, attributes may be repeated in a policy. For certain policies, the attributes repetition cannot be avoided even after applying the boolean optimization techniques to attain an equivalent smaller length boolean formula. For such policies, the evaluated secret shares are also multiple for repeated attributes; hence, the ciphertext computed for those irreducible policies is long and computational effort is more. To address this issue, a new CP-ABE scheme is proposed which employs our Repeated Attributes Optimization algorithm by which the Linear Secret Sharing Scheme matrix sent along with ciphertext will contain the access structure of policy including attributes appearing multiple times, but the ciphertext will only be evaluated for unique non-repeated attributes. Security and performance analysis show that the proposed construction fulfils its goals of achieving desired security with low communication overhead and computational cost for resource-constrained devices.

Group key establishment protocol is the primary requirement of several group-ware applications, like secure conferences, pay per view, collaborative work space that needs to establish a secure session among a group of participants. However, some of the applications often need to establish a secure session among the participants without knowing their actual identities. In such cases, the legitimacy of participants is decided based up on a descriptive set of attributes usually called as access structure. The participants should have sufficient set of attributes to satisfy the access structure, which are to consider as authenticated and eligible for the group conversation. This paper introducing an attribute based authenticated group key transfer protocol without using bilinear pairing. Group key management based on attributes gives fine-grained access control over the group of members that are authenticated by the set of attributes. The proposed protocol uses, Shamir Secret Sharing and elliptic curve arithmetic instead of bilinear pairing computations. The members are authenticated based on the access structure defined by the session initiator. The group key is securely transferred to only those participants, who are authenticated by their attributes. The authentication process of proposed protocol is information theoretically secure, while the key confidentiality relies on the intractability of Elliptic Curve Discrete Logarithm Problem.

We improve the flexibility in designing access structures of quantum stabilizer-based secret sharing schemes for classical secrets, by introducing message randomization in their encoding procedures. We generalize the Gilbert-Varshamov bound for deterministic encoding to randomized encoding of classical secrets. We also provide an explicit example of a ramp secret sharing scheme with which multiple symbols in its classical secret are revealed to an intermediate set, and justify the necessity of incorporating strong security criterion of conventional secret sharing. Finally, we propose an explicit construction of strongly secure ramp secret sharing scheme by quantum stabilizers, which can support twice as large classical secrets as the McEliece-Sarwate strongly secure ramp secret sharing scheme of the same share size and the access structure., Publisher's Open Access PDF. arXiv admin note: text overlap with arXiv:1811.05217

With the evolution of the fifth generation (5G) and beyond heterogeneous wireless networks, telecommunications operators and researchers are driven to develop advanced transmission technologies that enable the coexistence of multiple radio access technologies (multi-RATs). By employing the efficient implementation of filter-bank multi-carrier (FBMC) transceiver and the scalable matrix transformation (SMT) module, in this study, a unified multiple access architecture termed as FBMC-SMT is proposed, which is capable of flexibly integrating with both 3G and 4G transmission schemes and improving the system performance. As a special case of FBMC-SMT, the performance evaluation of FBMC-CDMA is conducted by extensive simulation. It is verified that FBMC-CDMA with 16 subbands allocated outperforms the traditional single carrier wideband code division multiple access when the number of code channels assigned is larger than 5. Moreover, the signal-to-interference-plus-noise ratio analysis of FBMC-SMT is also given and matches the simulation results very well. Hence, the proposed FBMC-SMT can serve as a unified architecture to flexibly integrate multi-RATs, thus to meet variable application requirements in 5G and beyond heterogeneous wireless networks.

Boolean-operation-based secret image sharing (BSIS), which aims to encode a secret image into some shared images and discloses the original secret image later, has drawn more and more attention in academia. Since Chen and Wu pioneer in proposing the Boolean-operation-based multiple secret image sharing (BMSIS) scheme, there more and more BMSIS schemes proposed in the literature. In order to remove the limitation that in the existing BMSIS schemes, this paper presents Boolean-operation-based multiple-secret image sharing with general access structure for secret reconstruction. Compared with the existing related BMSIS schemes with the property of all-or-nothing reconstruction, the proposed scheme achieves a milestone, i.e., secrets can be reconstructed by the pre-defined access structure. Hence, the secret reconstruction no longer needs to collect all share images. Furthermore, distinct combinations of shares have the ability to disclose the secrets defined in the qualified set. The theoretical analysis and the experimental results demonstrate the proposed scheme does work.

Cloud file storage systems are the current trend of enterprises and also of individual users. Due to the malicious or unauthorized users, file sharing among the cloud users has become the biggest challenge in the recent times. Attribute-based signcryption (ABSC) is known as the versatile cryptographic primitive which achieves the fine-grained access control over robust cloud storage. ABSC combines attribute-based encryption (ABE) and attribute-based signatures to achieve privacy-oriented confidentiality along with the authenticity. Unfortunately, most of the present ABE and ABSC schemes leverage heavy computational overheads against the key length, the ciphertext size or the expressive access structures used. In this paper, a new ABSC scheme is devised to reduce computational overheads, more particularly, at cloud by introducing the more expressive hypergraph access structure, Attribute HyperGraph. On a positive note, the proposed system outperforms and shows less cloud computational timing without exponentiations unlike Deng et al. (IEEE Access 6:39473–39486, 2018. https://doi.org/10.1109/ACCESS.2018.2843778 ), Liu et al. (Future Gener Comput Syst 52:67–76, 2015. https://doi.org/10.1016/j.future.2014.10.014 ) and Li et al. (IEEE Trans Parallel Distrib Syst 25(8):2201–2210, 2014. https://doi.org/10.1109/TPDS.2013.271 ) schemes. Subsequently, the system does not incur any cryptographic computations associated with designcryption at cloud unlike Deng et al. (2018).

Secure multi-party computation is an important research area in cryptography, and the secret sharing scheme (SSS) is one of the main tools for constructing multi-party computation protocols. The access structure and the adversary structure are two important subsets of participants in an SSS. In general, the collection of all qualified subsets that can reconstruct the secret s, is known as an access structure, while no information regarding this secret is available to any unqualified subsets, and the collection of unqualified subsets is described as an adversary structure. The maximal adversary, which will become a qualified subset if any one participant not in this unqualified subset is added. At present, there is no effective algorithm to determine the maximal adversary structure for any given access structure. In this paper, we propose two algorithms to determine the maximal adversary structure from any given access structure, in which a binary tree is introduced to construct such algorithms. Moreover, a special type of access structure is established, from which the maximal adversary structure can be directly characterized, and the maximal adversary structure in this case is shown to be the largest when the number of participants of each qualified polynomial in the access structure is three.

We propose a key-policy attribute-based encryption (KP-ABE) scheme with constant-size ciphertexts, whose selective security is proven under the decisional linear (DLIN) assumption in the standard model. The proposed scheme also has semi-adaptively security, which is a recently proposed notion of security. The access structure is expressive, that is given by non-monotone span programs. It also has fast decryption, i.e., a decryption includes only a constant number of pairing operations. As an application of our KP-ABE construction, we also propose a fully secure attribute-based signatures with constant-size secret (signing) keys from the DLIN. For achieving the above results, we employ a hierarchical reduction technique on dual pairing vector spaces and a modified form of pairwise independence lemma specific to our proposed schemes.

In this modern age we generate data from various sophisticated systems and technologies for our personal use, the security and privacy of the data becomes a major concern while sharing it over the cloud platform. The conventional CP-ABE scheme is used to secure different types of data.The CP-ABE uses the access policy in the form of access tree for generating keys to encrypt and decrypt data. However using an explicit access structure with several nodes requires more computational requirements and consumes significant amount of time to process every node of access structure and to encrypt the data. In this paper, to overcome these challenges, we proposed a simplified Ciphertext Policy Attribute Based Encryption for multimedia applications scheme without an access structure, which is more practical to secure the data with less overhead. In this proposed work, the owner of the data carefully frames the attribute string in a prescribed manner that can be used for encryption and decryption process. The performance measurement of the proposed scheme demonstrate that our system has high level of security with less computational requirements.

Cloud users are outsourcing their data day-by-day resulting in huge amount of data storage in Cloud server. Cloud service provider (CSP) themselves may go for modifying the data that leads to data integrity problem. Unauthorized users illegally gain access to the data stored in cloud server. Therefore, providing protection, achieving privacy and access control for user’s data are big challenges in the Cloud. Ciphertext-policy attribute-based encryption (CP-ABE) is prominent encryption technique to solve the exigent dilemma of secure data sharing in cloud computing. The shared data files generally have the characteristic of multilevel hierarchy, predominantly in the areas of IT companies, healthcare and military; these areas require a multi-authority access control. However, the hierarchy construction of shared files and multi-authority access control approach are not been investigated in CP-ABE. This paper proposes an efficient multi-authority access control using attribute-based encryption scheme that achieves efficient, fine grained access control. The proposed scheme consists of one algorithm – (Role Hierarchy Algorithm (RHA) and Hierarchy Access Structure (HAS) to protect user’s data, achieve privacy, multi-authority access control and fine grained access to a stored data. The RHA algorithm classifies Cloud users into groups based on their assigned attributes. The HAS helps to define an access structure for fine grained and multi-authority access control of Cloud resources. Simulation results prove that the proposed RHA, HAS are efficient (in terms of time consumption and storage consumption for encryption, decryption) compared to existing works. The advantages of proposed scheme become more and more conspicuous when there is more number of files at Cloud storage server.

Quantum secret sharing plays an important role in quantum cryptography. In this paper, we propose a new general quantum secret sharing scheme based on access structure and monotone span program. In our scheme, the secret distributor first distributes the secret share according to the access structure, and then each participant in the authorization set hides their secret share in the qubits, and then transmits each qubit safely performed on unitary transformation. Compared with the existing quantum secret sharing schemes, our scheme is more flexible, general and less computational cost in practical applications.

Homomorphic (resp. abelian) secret sharing is a generalization of ubiquitous linear secret sharing in which the secret value and the shares are taken from finite (resp. abelian) groups instead of vector spaces over a finite field. Homomorphic secret sharing was first defined by Benaloh and, later in the early nineties, Frankel and Desmedt presented some relevant results. Except for a few other related topics such as black-box secret sharing and secret sharing over rings, the subject has remained dormant for about three decades. The study of homomorphic secret sharing is resumed in this paper and three main results are presented: (1) mixed-linear schemes, a subclass of abelian schemes to be introduced in this paper, are more powerful than linear schemes in terms of the best achievable information ratio (the claim is proved for the port of a well-known almost entropic matroid), (2) the information ratios of dual access structures are equal for the class of abelian schemes and (3) every ideal homomorphic scheme can be transformed into an ideal linear scheme with the same access structure.

Secret sharing is an integral part of CP-ABE implementation. Currently, Linear Secret Sharing Scheme (LSSS) and Lagrange interpolation are used in existing CP-ABE implementation. Implementation is complex and computational cost is high for generating the access tree structure using these schemes. In this paper, a novel construction of CP-ABE has been developed which implements counting based secret share generation and reconstruction method to generate access tree structure and reconstruct secret shares. The proposed development reduces the cost of access structure generation and reconstruction of secret and improves security by generating the large number of secret shares for small-sized secret. Hence, the new construction enhances the efficiency of encryption and decryption operations of CP-ABE.

Cloud computing facilitates the access of applications and data from any location by using any device with an internet connection. It enables multiple applications and users to access the same data resources. Cloud based information sharing is a technique that allows researchers to communicate and collaborate, that leads to major new developments in the field. It also enables users to access data over the cloud easily and conveniently. Privacy, authenticity and confidentiality are the three main challenges while sharing data in cloud. There are many methods which support secure data sharing in cloud environment such as Attribute Based Encryption(ABE), Role Based Encryption, Hierarchical Based Encryption, and Identity Based Encryption. ABE provides secure access control mechanisms for integrity. It is classified as Key Policy Attribute Based Encryption(KP-ABE) and Ciphertext Policy Attribute Based Encryption(CP-ABE) based on access policy integration. In KPABE, access structure is incorporated with user’s private key, and data are encrypted over a defined attributes. Moreover, in CPABE, access structure is embedded with ciphertext. This paper reviews CP-ABE methods that have been developed so far for achieving secured data sharing in cloud environment.

In public cloud storage services, data are outsourced to semi-trusted cloud servers which are outside of data owners' trusted domain. To prevent untrustworthy service providers from accessing data owners' sensitive data, outsourced data are often encrypted. In this scenario, conducting access control over these data becomes a challenging issue. Attribute-based encryption (ABE) has been proved to be a powerful cryptographic tool to express access policies over attributes, which can provide a fine-grained, flexible, and secure access control over outsourced data. However, the existing ABE-based access control schemes do not support users to gain access permission by collaboration. In this paper, we explore a special attribute-based access control scenario where multiple users having different attribute sets can collaborate to gain access permission if the data owner allows their collaboration in the access policy. Meanwhile, the collaboration that is not designated in the access policy should be regarded as a collusion and the access request will be denied. We propose an attribute-based controlled collaborative access control scheme through designating translation nodes in the access structure. Security analysis shows that our proposed scheme can guarantee data confidentiality and has many other critical security properties. Extensive performance analysis shows that our proposed scheme is efficient in terms of storage and computation overhead.

Due to wide applications in communications, data storage, and cryptography, linear codes have received much attention in the past decades. As a subclass of linear codes, minimal linear codes can be used to construct secret sharing schemes with nice access structure. This paper gives the weight distributions of four classes of minimal binary linear codes with $$w_{min}/w_{max}

Ciphertext-policy attribute-based keyword search (CP-ABKS) schemes facilitate the fine-grained keyword search over encrypted data, such as those sensed/collected from Industrial Internet of Things (IIoT) devices and stored in the cloud. However, existing CP-ABKS schemes generally have significant computation and storage requirements, which are beyond those of resource-constrained IIoT devices. Therefore, in this paper, we design a secure online/offline data sharing framework (DSF), which supports online/offline encryption and outsourced decryption. Using the healthcare setting as a case study, we demonstrate how DSF can be deployed in the cloud-assisted Healthcare IIoT (HealthIIoT) system. We not only prove that the DSF is selectively secure in the chosen access structure security model but also demonstrate its efficiency and feasibility in practical scenarios using experiments.

Attribute based encryption (ABE) is an encryption technique which provides a good solution to the security issues in the cloud environment. Through ABE, a data owner can achieve the fine-grained sharing of data encrypted under attributes or an access policy which they possess. The relation among these attributes is represented by the access policy which is expressed as an access tree. In this article, the authors first present an ABE scheme which supports frequent changes in the access tree and hence, it is named a dynamic policy ABE. Also, the proposed scheme generates secret keys of constant size which can save bandwidth. The proposed scheme is based on key-policy design and supports monotonic access structure that consists of AND, OR and Threshold gates. Inspired by the proposed dynamic policy ABE scheme the authors then present a multi-keyword search scheme which inherits all the features of the proposed ABE scheme. Therefore, it provides a constant size trapdoor and support for fast search. The construction of a multi-keyword search scheme is generic in nature and any ABE scheme can be converted to the multi-keyword search scheme using the transformation method given in the paper. Finally, the proposed schemes are proven to be secure under Decisional Bilinear Diffie-Hellman (DBDH) assumption.

Based on the homogeneous linear recursive equation and the Elliptic curve cryptography (ECC), a fully dynamic secret sharing scheme is proposed for the general access structure of the participants. The participants choose their own shadows by themselves. When the shared secrets are updated, the access structure is changed, and other participants are added to or deleted from the existed group, but the shadow of each participant remains unchanged. Each participant should only maintain a shadow to share the multiple secrets. Compared with the existing popular dynamic schemes, the key construction of the proposed scheme is simpler and the proposed scheme has a completely dynamic characteristic, so that it has the potential to extend its practical application scenarios. That is, the proposed scheme can improve the performances of the key management and the distributed system. The security of the scheme is based on the Shamir threshold scheme, the computational Diffie–Hellman problem (CDHP) and the discrete logarithm problem (DLP).