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Machine learning (ML) classification has been one of the most important techniques of popular Internet services that aim to provide accurate predictions of data by means of a classifier model. In a machine-learning-as-a-service (MLaaS) system, the service provider allows classifier owners to upload their classifier models and charge other users for access on a pay-per-query basis, so that a user can query a classifier with data instances and then obtain their classification results. However, in a traditional way, either stored classifiers or queried data, which are potentially sensitive and economical, will be exposed by the service. Due to privacy concerns, both the classifiers and the data should remain confidential. In this paper, we propose a novel scheme to enable a classifier owner to outsourcely store his/her classifier model on a cloud server for users' queries, while protecting the confidentiality of classifier and data. We adopt a trusted processor to design efficient classification protocols for two concrete classifiers respectively. For the communicational efficiency, users only need to interact with the server no more than twice for each query in our scheme. We implement the prototype of the scheme and conduct experiments in an Intel SGX enclave. The experimental results show that the scheme is practical. [ABSTRACT FROM AUTHOR]

Convolutional neural network has been proven to be a powerful semantic composition model for modelling sentences. A standard convolutional neural network usually consists of several convolutional and pooling layers at the bottom of a linear or non-linear classifier. In this paper, a new pooling scheme termed Attention Pooling is proposed to retain the most significant information at the pooling stage. An intermediate sentence representation generated by the bidirectional long short-term memory is used as a reference for local representations produced by the convolutional layer to obtain attention weights. The sentence representation is formed by combining local representations using obtained attention weights. The intermediate sentence representation is used as an input to the top classifier as well in the testing phase. The salient features of the proposed attention pooling-based convolutional neural network are: (1) The model can be trained end-to-end with limited hyper-parameters; (2) Comprehensive information is extracted by the new pooling scheme and the combination of the convolutional layer and the bidirectional long-short term memory; (3) The model can implicitly separate the sentences from different classes. Experimental results demonstrate that the new model outperforms the state-of-the-art approaches on seven benchmark datasets for text classification. The learning capability of the proposed method is greatly improved and the classification accuracy is even enhanced significantly by over 2% on some datasets. The robustness of the proposed model is evidenced by some statistical tests. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel self-embedding fragile image watermarking scheme for tampering recovery based on reference-data interleaving mechanism and adaptive selection of embedding mode. During watermark embedding, reference bits are derived from the interleaved, scrambled MSB bits of original image, and then are combined with authentication bits to form the watermark bits for LSB embedding. Different with the reported schemes with the fixed embedding mode, the proposed scheme not only has two types of embedding modes, i.e., overlapping-free embedding and overlapping embedding, but also utilizes the adaptively flexible numbers of MSB and LSB layers to achieve satisfactory performances for different tampering rates. Also, detailed analyses are given to provide the theoretical values of watermarked-image quality, perfect recovery probability, and recovered-image quality, which are used to conclude the optimal choice of embedding modes. Experimental results show the effectiveness and superiority of the proposed scheme compared with some state-of-the-arts schemes. [ABSTRACT FROM AUTHOR]

Public key encryption with equality test (PKEET), which was first introduced by Yang et al. (CT-RSA, 2010), has various applications including facilitating keyword search on encrypted data and partitioning encrypted data on the cloud. It can be also applied to manage personal health records on the internet. For these reasons, there have been improvements on earlier PKEET schemes in terms of performance and functionality. We present a semi-generic method for PKEET constructions, assuming only the existence of IND-CCA2 secure traditional public key encryption (PKE) schemes, the hardness of Computational Diffie-Hellman (CDH) problems, and random oracles. Our approach has several advantages; it enables us to understand requirements for the equality test functionality more clearly. Furthermore, our approach is quite general, in that if we change the underlying PKE scheme with the identity-based encryption (IBE) scheme (and we assume the hardness of Bilinear Diffie-Hellman problems instead of CDH), then we obtain the first IBE scheme with equality test (IBEET) satisfying analogous security arguments to those of PKEET. Although an IBEET construction was recently proposed, but we note that it satisfies only weak security requirements. [ABSTRACT FROM AUTHOR]

This paper studies multiple coordination of multi-agent networks under an event-driven paradigm. For an undirected connected graph, a node clustering scheme is first adopted to ensure a relatively strong degree of connectivity within each potential subgroup, and some repulsive effect is used to deal with the extra-subgroup links. To reduce unnecessary communication, a distributed event-driven controller is designed via coupled intra-subgroup and extra-subgroup information. Based on the LaSalle’s invariance principle, it is shown that under the proposed event-driven control configuration, multi-agent networks can realize multi-consensus without any balanced requirement on the underlying topologies. Simulation work is presented to validate the theoretical results. [ABSTRACT FROM AUTHOR]

Secret sharing (SS) is one of the most important cryptographic primitives used for data outsourcing. The ( t, n ) SS was introduced by Shamir and Blakley separately in 1979. The secret sharing policy of the ( t, n ) threshold SS is far too simple for many applications because it assumes that every shareholder has equal privilege to the secret or every shareholder is equally trusted. Ito et al. introduced the concept of a general secret sharing scheme (GSS). In a GSS, a secret is divided among a set of shareholders in such a way that any “ qualified ” subset of shareholders can access the secret, but any “ unqualified ” subset of shareholders cannot access the secret. The secret access structure of GSS is far more flexible than threshold SS. In this paper, we propose an optimized implementation of GSS. Our proposed scheme first uses Boolean logic to derive two important subsets, one is called Min which is the minimal positive access subset and the other is called Max which is the maximal negative access subset, of a given general secret sharing structure. Then, conditions of parameters of a GSS are established based on these two important subsets. Furthermore, integer linear/non-linear programming is used to optimize the size of shares of a GSS. The complexity of linear/non-linear programming is O ( n ), where n is the number of shares generated by the dealer. This proposed design can be applied to implement GSS based on any classical SS. However, our proposed method is limited to be applicable to some general secret sharing policies. We use two GSSs, one is based on Shamir's weighted SS (WSS) using linear polynomial and the other is based on Asmuth-Bloom's SS using Chinese Remainder Theorem (CRT), to demonstrate our design. In comparing with existing GSSs, our proposed scheme is more efficient and can be applied to all classical SSs. [ABSTRACT FROM AUTHOR]

In this paper, we present two strongly secure pairing-free identity-based (ID-based) two-party authenticated key agreement (AKA) protocols achieving implicit authentication, which are proven secure in the extended Canetti–Krawczyk (eCK) model. The proposals can offer provable security against both passive and active adversaries in the random oracle model. Our schemes capture all basic desirable security properties including key-compromise impersonation resilience, ephemeral secrets reveal resistance, (weak) perfect forward secrecy and master key forward secrecy etc. We show the security of one of these proposals can be reduced to the standard computational Diffie–Hellman assumption, and the security of the other relies on the gap Diffie–Hellman assumption while having a lower computational overhead. Currently, there are few pairing-free ID-based AKA protocols that are provably secure in such strong security models as the eCK model. Our schemes can provide strong security assurances and in the meanwhile achieve a good computational efficiency. Compared with previous related schemes, our protocols have advantages over them in security, efficiency or both. [ABSTRACT FROM AUTHOR]

In mobile e-commerce systems, users conduct transactions using wireless or Internet-based devices, such as mobile phones and tablets. It is different from traditional e-commerce systems relying on workstations or desktops, which is usually used in a fixed location. Recently, privacy and accountability have become users’ primary concerns in mobile e-commerce applications. In this paper, a novel mobile e-commerce scheme is developed to address the fundamental requirements. We first propose an identity-based plaintext-checkable encryption (IBPCE) scheme where anyone can check whether a ciphertext is the encryption of a plaintext under a specific identity without knowing the secret key. Furthermore, the proposed IBPCE scheme is incorporated into the mobile e-commerce scenario, which results in an accountable mobile e-commerce (AMEC) scheme. Our proposed AMEC scheme has several superior features: (1) Users can register to the e-commerce system by using their mobile identities, such as mobile phone numbers; (2) The transactions between a buyer and a vendor are encrypted; (3) If there is a dispute, an offline adjudicator can identify who is dishonest by checking the encrypted transactions. We evaluate the proposed scheme and confirm that the new scheme can effectively balance the need for privacy and accountability. [ABSTRACT FROM AUTHOR]

This paper presents a new measurement-based control design method for cancer chemotherapy. Cancer chemotherapy aims basically at simultaneously eradicating or significantly reducing the number of cancer cells and maintaining tolerable levels of drug concentration and toxicity. To achieve such aim, drugs are often injected into the patient’s body according to a drug schedule specifying the drug dose and delivery time. Several strategies for planning cancer chemotherapy have been developed in the literature, where evolutionary algorithms have been applied to find optimal drug schedules of cancer treatment under constraints on some key treatment parameters such as drug concentration and toxic side effects. In such methods, the amount of drug doses, delivered in the body at each time during the treatment, does not depend on the current drug concentration, toxicity level, and/or number of cancer cells. Successful design of chemotherapy drug scheduling requires the availability of an accurate mathematical model that perfectly predicts the number of cancerous cells and describes effects of treatment. Several models with either complex or simple structures are available in the literature. Complex-structure models are proposed to deeply understand interactions between cancer and normal cells that affect the performance of the cancer chemotherapy. Nevertheless, such complex models are based on a high-order set of differential equations which can be difficult to solve. Simple-structure models, which are often obtained on the basis of some simplifying assumptions, can be viewed only as an approximation of the cancer system. Hence, designing chemotherapy drug schedules on the basis of simplified models may result in unsuccessful cancer treatment. Unlike conventional control strategies for cancer chemotherapy, our attempt in this paper is to address the problem of designing a control system for cancer treatment using a set of frequency-domain data. Hence, a two-degree-of-freedom PID (proportional-integral-derivative) control scheme is proposed to control cancer growth. These PID controllers are designed to simultaneously provide the optimal amount of drug doses to be delivered into the patient’s body according to the current drug concentration and toxicity level, and maintain the drug concentration and toxicity levels within their pre-specified ranges. The proposed cancer control technique is validated through a first simulation example. Another example to control biological systems is also presented to show the feasibility of the proposed method. Simulation results obtained have demonstrated the capability of the proposed control scheme to address cancer chemotherapy problems. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the performance of a continuous biometric authentication system under various different analysis techniques. We test these on a publicly available continuous mouse dynamics database, but the techniques can be applied to other biometric modalities in a continuous setting also. We test all different combinations of fusion techniques, threshold settings, score boosting techniques and static versus dynamic trust models. We extensively describe the way that performance is reported when analyzing the performance of a continuous authentication system. Contrary to a biometric system for access control at the start of a session can the performance not simply be reported by a single EER value or a DET curve. We show that the optimal performance we can reach with our new techniques improves significantly over the best known performance on the same dataset. [ABSTRACT FROM AUTHOR]

Secure aggregate signature schemes are very useful tools in special areas where the signatures on many different messages generated by many different users need to be compressed. Quite recently, an efficient certificateless aggregate signature scheme was presented by Xiong et al. (2013). Although they proved its security in the random oracle model under the standard computational Diffie–Hellman assumption, we find that their conclusion is wrong. In this paper, we give security analysis to their scheme by showing four kinds of concrete attacks. The first two kinds of attacks come from an honest - but - curious KGC and a malicious - but - passive KGC respectively. While the last two are from the collusion of inside signers or the collusion of an insider signer with a malicious - but - passive KGC. Our analysis indicates coalition attacks, especially those from the collusion of an inside signer with a malicious KGC are practical and destructive, and hence should be prevented in the design of CLAS schemes. We also put forward a secure certificateless aggregate signature scheme. Our new aggregate signature scheme results in a short aggregate signature that is valid if and only if every individual signature involved in the aggregation is valid. [ABSTRACT FROM AUTHOR]

In this paper, we first propose a scheme to learn with automatically aligned objects for image categorization. To fulfil this purpose, the learning is formulated into a multiple instance learning problem with bags. Each bag is a virtually generated image set from an original image. The virtually generated image set covers multiple possible object locations, scales and views. Secondly, we propose a novel adaptive learning method to take advantage of the sharing information among different categories in image categorization. The method models the sharing information between one category and the other categories by learning a classifier of the current category from perturbed pre-learned classifiers from other categories. And the adaptive learning is realized in the multiple kernel learning framework. Finally, to align the images from one category and share the information among different categories simultaneously, the proposed multiple instance learning scheme and the proposed adaptive learning method are integrated into one learning framework. A new formulation called Adaptive Multiple Instance Learning (A-MIL) is derived. The optimization method is provided. To evaluate the proposed method, comprehensive experiments are conducted on two well-known public image categorization datasets (Caltech101 and 15Scenes). The experimental results show that the proposed method outperforms the state-of-the-arts in classification accuracy. [ABSTRACT FROM AUTHOR]

The main function of recommender systems (RSs) is to recommend user-customized information to customers or system users. Correct and useful information is crucial for both customers and service providers. The influence of RSs is expanding over the Internet. However, criminal users try to manipulate the results of RSs with fake identities (i.e., Sybils) for financial gain. Effective metrics are consequently required for defense against Sybil attack. In this paper, we first explore two metrics, stickiness and persistence , from the perspective of the RS security domain. We then propose practical detecting schemes, Dy namic Sy bil Attack Monitoring on Rec ommender Systems ( DySy-Rec ) and F uzzy rule-based DySy-Rec ( FDySy-Rec ), which apply stickiness and persistence in two real datasets from real movie RSs. To demonstrate the effectiveness and potential of DySy-Rec and FDySy-Rec , we conducted extensive experiments on the inclusion of more diverse and smart types of attacks. The experimental results show that the proposed schemes achieve substantial performance improvement compared with previous statistical approaches in terms of precision and recall. Finally, the results confirm the practical possibilities of exploiting stickiness and persistence in the fight against dynamic Sybil attacks in online RSs. [ABSTRACT FROM AUTHOR]

Lipmaa et al. introduced a new security notion of designated verifier signature schemes, non-delegatability: neither a signer nor a designated verifier can delegate the signing rights to any third party without revealing their secret keys. In this paper, we classify designated verifier signature schemes into three types and then discuss delegatability of existing designated verifier signature schemes, strong designated verifier signature schemes and universal designated verifier signature schemes, and open research issues. [ABSTRACT FROM AUTHOR]

In this paper we describe a cryptanalysis of a key exchange scheme recently proposed by Álvarez, Tortosa, Vicent and Zamora. The scheme is based on exponentiation of block matrices over a finite field of prime order, and its security is claimed to rely in the hardness of a discrete logarithm problem in a subgroup of . However, the proposal’s design allows for a clean attack strategy which exploits the fact that exponents are at some point added instead of multiplied as in a standard Diffie–Hellman construction. This strategy is moreover successful for a much more general choice of parameters than that put forward by Álvarez et al. [ABSTRACT FROM AUTHOR]

Abstract: Zhang et al. proposed recently a group-oriented multisigncryption scheme with threshold designcryption and affirmed that their scheme is secure under standard complexity assumptions. However, the note elaborates concrete attacks on its indistinguishability and unforgeability under their security models. We also provide the impossibility result of public ciphertext authenticity for the scheme. [Copyright &y& Elsevier]

Abstract: Edge orientations play an important role in recognition due to their function as a primitive visual feature for various kinds of recognition tasks. Filter-based schemes are the most well-known and widely used method for analyzing edge orientation. However, the classical filter-based approach passes not only edges inside the preferred orientation band, but also edges outside the band. This can cause ambiguity in the estimation of edge orientation and can subsequently lead to failure in recognition tasks where edge orientations are used as a primitive feature. In this paper, we propose a novel filtering scheme, referred to as oriented edge-selective band-pass filtering, which passes edges inside the preferred orientation band and prevents edges outside the band from passing through. We present a computational model based on the basic mechanisms of cortical processing, i.e., a recurrent framework integrating the feedforward, lateral, and feedback processes, with the aim of investigating a solution based on the psychophysical and neuro-physiological findings of several decades. In the feedforward stage, our model employs a classical filter-based method to allow as many edges as possible in the preferred orientation band to pass through, while also allowing some edges outside the band to pass. The responses of edges outside the band are then inhibited by recurrent processing, involving two steps: a lateral and a feedback stage. We evaluated the performance of our model against classical filter-based methods, such as Gabor and Neumann filtering, using several artificial and natural images. The results validated the effectiveness of our approach. [Copyright &y& Elsevier]

Abstract: This paper proposes an identity-based (ID-based) signature (IBS) scheme which is strongly unforgeable in the standard model whose security is reduced to the hardness of the computational Diffie-Hellman (CDH) problem in bilinear groups. Currently, the ID-based encryption scheme (IBE) due to Waters is known to be the most practically efficient IBE whose security is guaranteed in the standard model depending on the decisional bilinear Diffie-Hellman (BDH) assumption. While as a solution for an ID-based signature of a total ID-based public key cryptosystem cooperating with Waters IBE, we share Waters’s construction and system parameters to keep a key pair corresponding to each identity unchanged, our IBS needs only one group element for signing of messages and two elements for its randomness as supplementary parameters plus the original system parameters. Accordingly, thanks to requiring about half the system parameters against previous ID-based signatures proved secure without using random oracles under the standard complexity assumptions like CDH or BDH, our IBS is the more suitable for storage and communication requirements. In particular, this covers a stronger security property called strong unforgeability in the standard model in itself without applying any transformation technique. [Copyright &y& Elsevier]

Abstract: Proxy multi-signature allows a group of original signers to delegate their signing capabilities to a proxy signer in such a way that the proxy signer can sign messages on behalf of the group of original signers. Existing constructions of proxy multi-signatures are based on traditional Public Key Infrastructure or Identity-based Public Key Setting, but the former needs certificates which bring about many certificate management problems, and the latter has a drawback of key escrow. In contrast to the existing constructions, in this paper, we study proxy multi-signature in Certificateless Public Key Cryptography (CL-PKC) which combines the advantages of both certificate-based and identity-based cryptosystems as it avoids the use of certificates and does not suffer from key escrow. We provide the definition and the security model for Certificateless Proxy Multi-Signature (CLPMS), and propose the first CLPMS scheme which is proved to be secure in the random oracle model under the computational Diffie–Hellman assumption. Our scheme is computationally efficient and has the property that the size of a proxy multi-signature is independent of the number of the original signers. [Copyright &y& Elsevier]

Highlights: [•] We model access control of sensitive data between multiple organizations. [•] We propose Ciphertext-Policy Hierarchical Attribute-Based Encryption (CP-HABE). [•] CP-HABE is equipped with key delegation for users of different organizations. [•] The first CP-HABE scheme is presented with short ciphertexts. [•] Our scheme is proven secure in standard model under static assumptions. [ABSTRACT FROM AUTHOR]

Abstract: In a Private Matching (PM) scheme, the client C has a dataset X of m elements, and the server S has a dataset Y of n elements. The client C can learn the set intersection without leaking any information to the server S. Previously, the most efficient PM scheme requires communication of complexity , which increases linearly with n. This may not be efficient enough in Client–Server models because the server’s dataset Y is usually large. In this paper, we propose a PM scheme based on Oblivious Transfer (OT) and universal hash function. Our scheme requires communication of complexity . Thus, our scheme is especially suitable for Client–Server models. We show that our scheme becomes more efficient when for security parameter . However, utilizing the universal hash function would cause a mismatch issue which affects the accuracy of the PM scheme. In addition, it leaks the server’s information. Therefore, we define approximate PM by relaxing the definition of PM; it is proved to be almost as secure as a PM scheme in a Client–Server model with proper configurations. [Copyright &y& Elsevier]

Abstract: A directed signature scheme is devised to achieve directivity for verification such that only a designated verifier can check the validity of a signature and, in times of trouble, any third party can verify the signature with the help of the signer or the designated verifier. A threshold directed signature scheme distributes responsibility and authority for generating a directed signature to several users via a threshold mechanism. Lu et al. recently proposed a novel threshold directed signature scheme. In this paper, we show that the scheme is vulnerable to a rogue-key attack which is mounted by an adversary who can arbitrarily select his or her public key. Through the rogue-key attack, the adversary can forge a signature on any message for a set of signers. In order to thwart such a rogue-key attack, we propose an enhanced threshold directed signature scheme with a reliable key registration protocol. The protocol guarantees that a user should have access to the secret key corresponding to the user’s public key. Under the computational Diffie-Hellman assumption, we prove that the improved scheme is secure, that is, it achieves existential unforgeability under the chosen message attack, invisibility, and transitivity in the registered key model. We stress that the security of our improved scheme does not depend on a specific broadcast channel for synchronous message transmission. [Copyright &y& Elsevier]

Abstract: In an attribute-based signature (ABS) system, a signature does not give proof of the identity of the individual who signed a message; it instead gives proof to a claim regarding the attributes that the underlying signer owns. For ABS, investigators have found many practical applications that require signer-attribute privacy. However, this approach is inadequate for handling scenarios in which the signing key is exposed due to viruses, worms or other break-ins that are allowed by operating-system holes. To overcome the limitation of existing ABS systems, we introduce the notion of an attribute-based key-insulated signature (ABKIS), in which signing keys are refreshed at discrete time periods via an interaction between the user and the helper (a physically-secure but computationally-limited device). We formalize this security model and propose a concrete ABKIS scheme, which is proven to be secure under the standard computational Diffie–Hellman assumption. Furthermore, as an application, a time-conditioned attribute-based proxy signature (TC-ABPS) is derived from our proposed ABKIS scheme. Another typical application of our scheme is for anonymous provider authentication in a bidirectional broadcasting service. [Copyright &y& Elsevier]

Abstract: In this paper, we present different opposition schemes for four reinforcement learning methods: Q-learning, Q( ), Sarsa, and Sarsa( ) under assumptions that are reasonable for many real-world problems where type-II opposites generally better reflect the nature of the problem at hand. It appears that the aggregation of opposition-based schemes with regular learning methods can significantly speed up the learning process, especially where the number of observations is small or the state space is large. We verify the performance of the proposed methods using two different applications: a grid-world problem and a single water reservoir management problem. [Copyright &y& Elsevier]

Abstract: Many efforts have been devoted in recent years to constructing secure schemes in certificateless cryptography. The aim is to eliminate the key escrow problem of identity-based cryptography. However, most of the work takes place in traditional certificateless cryptography, which suffers from the single-point problem. Hierarchical cryptography exploits a practical security model to mirror the organizational hierarchy in the real world and hence can eliminate the single-point problem. To incorporate the advantages of both types of cryptosystems, in this paper we instantiate hierarchical certificateless cryptography by formalizing the notion of hierarchical certificateless signatures. A concrete hierarchical certificateless signature scheme is also proposed. The security of our scheme is proven under the computational Diffie-Hellman assumption. As to efficiency, our scheme has constant complexity, regardless of the depth of the hierarchy. Therefore, our proposal is secure and scalable. [Copyright &y& Elsevier]

Abstract: We present a family of character-based index schemes for wildcard search in peer-to-peer networks. The supported query format allows the two wildcard matching operators ‘?’ and ‘*’ to be used arbitrarily. To our knowledge, no distributed solution for this general form of wildcard search has been proposed thus far. Moreover, the schemes can achieve balanced loads, avoid hot-spots and single points of failure, reduce storage and maintenance costs, and offer ranking mechanisms for matching objects. The main focus is on a thorough comparative study on these index schemes from the following perspectives: query expressiveness, encoding effectiveness, load balance, and search performance. [Copyright &y& Elsevier]

Abstract: Visual cryptography scheme (VCS) encodes a visual information (pictures, text, etc.) into several noise-like shadow images. In VCS, each shadow image can be made on a transparency. By stacking transparencies and stack them on an overhead projector, we can visually decode the secret through human visual system without the assistance of any hardware or computation. However, noise-like shadows of VCS were suspected to censors and difficult for identification and management. Therefore, the extended VCS (EVCS) with meaningful shadow images had been proposed to address this problem of suspicion. In this paper, we employ a digital halftoning technology to propose a new EVCS whose shadow images are clearer in comparing with existing EVCSs. [Copyright &y& Elsevier]

Abstract: The notion of chameleon hash function without key exposure plays an important role in designing secure chameleon signatures. However, all of the existing key-exposure free chameleon hash schemes are presented in the setting of certificate-based systems. In 2004, Ateniese and de Medeiros questioned whether there is an efficient construction for identity-based chameleon hashing without key exposure. In this paper, we propose the first identity-based chameleon hash scheme without key exposure based on the three-trapdoor mechanism, which provides an affirmative answer to the open problem. Moreover, we use the proposed chameleon hash scheme to design an identity-based chameleon signature scheme, which achieves all the desired security properties. [Copyright &y& Elsevier]

Abstract: A fundamental approach for secure data sharing in a cloud environment is to let the data owner encrypt data before outsouring. To simultaneously achieve fine-grained access control on encrypted data and scalable user revocation, existing work combines attribute-based encryption (ABE) and proxy re-encryption (PRE) to delegate the cloud service provider (CSP) to execute re-encryption. However, the data owner should be online in order to send the PRE keys to the CSP in a timely fashion, to prevent the revoked user from accessing the future data. The delay of issuing the PRE keys may cause potential security risks. In this paper, we propose a time-based proxy re-encryption (TimePRE) scheme to allow a user’s access right to expire automatically after a predetermined period of time. In this case, the data owner can be offline in the process of user revocations. The basic idea is to incorporate the concept of time into the combination of ABE and PRE. Specifically, each data is associated with an attribute-based access structure and an access time, and each user is identified by a set of attributes and a set of eligible time periods which denote the period of validity of the user’s access right. Then, the data owner and the CSP are required to share a root secret key in advance, with which CSP can automatically update the access time of the data with the time that it receives a data access request. Therefore, given the re-encrypted ciphertext, only the users whose attributes satisfy the access structure and whose access rights are effective in the access time can recover corresponding data. [Copyright &y& Elsevier]

Abstract: This paper discusses interpretability in two main categories of fuzzy systems – fuzzy rule-based classifiers and interpolative fuzzy systems. Our goal is to show that the aspect of high level interpretability is more relevant to fuzzy classifiers, whereas fuzzy systems employed in modeling and control benefit more from low-level interpretability. We also discuss the interpretability–accuracy tradeoff and observe why various rule weighting schemes that have been brought into play to increase adaptability of fuzzy systems rather just increase computational overhead and seriously compromise interpretability of fuzzy systems. [Copyright &y& Elsevier]

Highlights: [•] Proposed a novel iterative meta-clustering technique. [•] Two clustering schemes evolve in parallel influencing each other recursively. [•] Demonstrated using retail store customers and products. [•] Static representation using information from the database. [•] Dynamic representation using information from previous clustering. [ABSTRACT FROM AUTHOR]

Abstract: In order to simplify certificate management in traditional public key cryptography and solve the key escrow problem in identity-based cryptography, the notion of certificate-based cryptography was introduced. Recently, Ming and Wang proposed a certificate-based signature scheme without pairings. They claimed that the scheme was existentially unforgeable against adaptive chosen message and identity attacks in the random oracle. In this paper, we show that the scheme is insecure against a malicious certifier under existing security model. We also propose a new efficient certificate-based signature scheme without pairings, which is proven secure in the random oracle model. Compared with the existed certificate-based signature schemes without parings, our scheme enjoys shorter signature length and less operation cost. [Copyright &y& Elsevier]

Abstract: It would be interesting if a signcryption scheme in the standard model could be made certificateless. One of the interesting attempts is due to Liu et al. [Z. Liu, Y. Hu, X. Zhang, H. Ma, Certificateless signcryption scheme in the standard model, Information Sciences 180 (3) (2010) 452–464]. In this paper, we provide a cryptanalysis on this scheme by depicting two kinds of subtle public key replacement attacks against it. Our analysis reveals that it does not meet the basic requirements of confidentiality and non-repudiation. [Copyright &y& Elsevier]

Abstract: Hidden Vector Encryption (HVE) is a special type of predicate encryption that can support conjunctive equality and range searches on encrypted data. All previous HVE schemes were proven to be either selectively secure or weakly attribute-hiding. In this paper, we first construct a new HVE scheme that is fully secure under standard assumptions. Our HVE scheme, which is based on bilinear maps (pairings), provides efficiency advantages in that it requires O(1)-sized private keys and O(1) pairing computations for decryption, regardless of both the number of conjunctives and the dimension of vectors. To achieve our goal, we develop a novel technique to realize a tag-based dual system encryption in prime-order groups and show how to hide vector components and compress tag values into one. [Copyright &y& Elsevier]

Abstract: Álvarez et al., Information Sciences 179 (12) (2009) proposed a new key exchange scheme where the secret key is obtained by multiplying powers of block upper triangular matrices whose elements are defined over . In this note, we show that breaking this system with security parameters is equivalent to solving a set of linear equations with unknowns in , which renders this system insecure for all the suggested practical choices of the security parameters. [Copyright &y& Elsevier]

Abstract: Recently, various offspring generation strategies and parameter adaptation mechanisms have been developed to enhance the reliability and robustness of differential evolution (DE). However, the population size is generally fixed throughout the evolutionary search in most existing DE-variants, which leads to unsatisfactory performance. Based on the solution-searching status, in this paper, an adaptive population tuning scheme (APTS) for DE is proposed to dynamically adjust the population size. More specifically, on the basis of a ranking technique, a dynamic population strategy is adopted to remove redundant individuals from the population according to its ranking order. It is also applied to perturb the population and generate “fine” individuals. The proposed APTS is controlled by a status monitor, which is used to keep track of the progress of individuals and improve the performance of dynamic population strategy. In addition, this APTS framework is incorporated into several recently reported DE variants. The experimental results over 25 commonly used CEC2005 test functions demonstrate the effectiveness and usefulness of the proposed method. [Copyright &y& Elsevier]

Abstract: In this paper we present a novel group signature scheme for dynamic membership which enables fine-grained control over the release of user information. This scheme could be widely used for various anonymity-based applications such as privacy-preserving data mining and customized anonymous authentication owing to a useful property called controllable linkability. A valid signer is able to create signatures that hide his or her identity as normal group signatures but can be anonymously linked regardless of changes to the membership status of the signer and without exposure of the history of the joining and revocation. From signatures, only linkage information can be disclosed, with a special linking key. Using this controllable linkability and the controllable anonymity of a group signature, anonymity may be flexibly or elaborately controlled according to a desired level. To begin construction of our scheme, we first introduce the Decision Linear Combination (DLC) assumption in a so-called gap Diffie–Hellman group where the DDH problem is tractable but the CDH problem is hard, and we prove that this assumption can be guaranteed in generic bilinear groups. To identify security requirements more precisely, we formally present definitions of anonymity, traceability, non-frameabilty, and linkability. We then prove that our scheme achieves all these security properties in the random oracle model. Our scheme supporting controllable linkability yields a short signature that is only 33.3% longer than the best-known normal group signature. Furthermore, we show that our scheme is comparable to the group signature scheme in terms of the amount of computation for basic operations such as signing, verification, and the key update caused by revocation. Finally, using the linkability for dynamic membership, computation overhead in opening signer’s identity can be significantly reduced or minimized. [Copyright &y& Elsevier]

Abstract: Wang et al. [B. Wang, Q. Wu, Y. Hu, Information Sciences 177 (2007)] proposed a knapsack-based probabilistic encryption scheme with non-binary coefficients which enjoys a high density larger than 1.06 in the worst case. In this work, we successfully attack this scheme by showing that a public key and a restriction on system parameters allow the attacker to recover a secret key in a cubic time complexity using modular equations. This approach is much more efficient than the previous attack by Youssef [A.M. Youssef, Information Sciences 179 (2009)], in which lattice basis reductions are used. Recovering secret keys can be done within 4h and 4days when n =100 and 200, respectively. A simple modification that helps resist known attacks is also discussed. [Copyright &y& Elsevier]

Abstract: At ACNS 2007, Ateniese and Green proposed the concept of ID-based proxy re-encryption (IBPRE), where a semi-trusted proxy with some information (a.k.a. re-encryption key), can transform a ciphertext under an identity to another ciphertext under another identity with the same plaintext. However, the proxy cannot obtain the plaintext. Recently, Wang et al. revisited this primitive by allowing the chosen ciphertext attack when the ciphertext could be transformed several times. They also proposed a concrete multi-use unidirectional ID-based proxy re-encryption (MUIBPRE) scheme, which is proven secure in the random oracle. Nonetheless, they left the problem of constructing a multi-use unidirectional IBPRE scheme in the standard model. What is worse, their scheme cannot resist the collusion attack, which is an important security requirement for unidirectional proxy re-encryption. To solve this problem, in this paper we present a conversion from non-anonymous hierarchical identity-based encryption (NaHIBE) with strongly CPA security to CCA-secure and collusion-resistant MUIBPRE. Furthermore, based on the NaHIBE scheme proposed by Waters at Crypto’09, we give the first CCA-secure and collusion-resistant MUIBPRE scheme in the standard model. [Copyright &y& Elsevier]

Abstract: Many real-world applications require management of uncertain data that are modeled as objects in high-dimensional space with imprecise values. In such applications, data objects are typically associated with probability density functions. A fundamental operation on such uncertain data is the probabilistic-threshold range query (PTRQ), which retrieves the objects appearing in the query region with probabilities no less than a specified value. In this paper, we propose a novel framework called MUD for efficient processing of PTRQs on high-dimensional uncertain data. We first propose a cost-effective pruning technique based on a very simple form of probabilistic pruning information (PPI), namely the probabilistic quantiles. Then we map high-dimensional uncertain objects to a single-dimensional space, where the quantiles of uncertain objects can be indexed using the existing single-dimensional indices such as the B+-tree. Each PTRQ in the high-dimensional space is transformed into multiple range queries on the single-dimensional space and evaluated there. We also discuss a method to optimize the indexing scheme for MUD. Specifically, we formulate a mathematical model for measuring the “pruning power” of quantiles, and propose a dynamic programming algorithm which selects the “best” quantiles for mapping and indexing. We perform extensive experiments on both synthetic and real data sets. Our experimental results reveal that the MUD framework is both effective and efficient for processing PTRQs on high-dimensional uncertain data, and it can significantly outperform state-of-the-art schemes. [Copyright &y& Elsevier]

Abstract: Recently, several fuzzy ontology-based solutions have been proposed in the domain of web-based applications to reduce the manual work load of daily activities. However, because of the explosive heterogeneity in the current internet structure, the performance of the available solutions has been decreasing drastically. We propose an integrated secure type-2 fuzzy ontology multi-agent platform (ST2FO-MAS) to completely automate the laborious process of manual air ticket booking. The air ticket booking domain is rife with uncertainties, and most of the information is based on complex linguistic terminologies. The available fuzzy ontology schemes cannot extract intensively blurred information from the internet to provide personalized solutions. Meanwhile, information security attacks have been growing significantly, which is a discouraging indicator for e-commerce applications. The proposed ST2FO-MAS can provide an end-to-end solution that can ideally address the ongoing information security challenges. The accommodation of a multi-agent system in a secure type-2 fuzzy ontology boosts the performance of the system because of its robust autonomous working scheme. To completely judge the performance of the proposed solution, we developed an intelligent prototype system that was based on JAVA, JADE and XML security recommendations. We conducted several experiments under the supervision of domain experts, and we evaluated the performance of the system. The experimental results are quite satisfactory and support the efficacy of the proposed model. [Copyright &y& Elsevier]

Abstract: Several types of evolutionary computing methods are documented in the literature and are well known for solving unconstrained optimisation problems. This paper proposes a hybrid scheme that combines the merits of a global search algorithm, the shuffled frog-leaping algorithm (SFLA) and local exploration, extremal optimisation (EO) and that exhibits strong robustness and fast convergence for high-dimensional continuous function optimisation. A modified shuffled frog-leaping algorithm (MSFLA) is investigated that improves the leaping rule by properly extending the leaping step size and adding a leaping inertia component to account for social behaviour. To further improve the local search ability of MSFLA and speed up convergence, we occasionally introduce EO, which has an excellent local exploration capability, in the local exploration process of the MSFLA. It is characterised by alternating the coarse-grained Cauchy mutation and the fine-grained Gaussian mutation. Compared with standard particle swarm optimisation (PSO), SFLA and MSFLA for six widely used benchmark examples, the hybrid MSFLA-EO is shown to be a good and robust choice for solving high-dimensional continuous function optimisation problems. It possesses excellent performance in terms of the mean function values, the success rate and the fitness function evaluations (FFE), which is a rough measure of the complexity of the algorithm. [Copyright &y& Elsevier]

Abstract: In this article, we introduce an application of swarm intelligence to distributed visual information retrieval distributed over networks. Based on the relevance feedback scheme, we use ant-like agents to crawl the network and to retrieve relevant images. Agents movements are influenced by markers stored on the hosts. These markers are reinforced to match the distribution of relevant images over the network. We tackle the use of the information gathered during previous search sessions. In order to match the different categories available on the network, we use several markers. Sessions searching for the same category will thus use the same makers. The system involves three learning problems: the selection of relevant markers regarding the searched category, the reinforcement of these markers and the learning of the relevance function. All of these problems are based on the relevance feedback loop. We test our system on a custom network hosting images taken from the well known TrecVid dataset. Our system shows a high improvement over classical content based image retrieval systems which do not use previous sessions information. [Copyright &y& Elsevier]

Abstract: Embedding secret data into a cover image using simple least-significant-bit substitution can degrade the image quality dramatically, especially when a large number of bits are substituted. The exhaustive least-significant-bit substitution method is proposed to solve this problem. However, the idea has no practical application due to its long computation time. This paper adopts the cat swarm optimization (CSO) strategy to obtain the optimal or near optimal solution of the stego-image quality problem. The CSO strategy is generated by observing the behavior of cats, which has been proved to achieve better performance on finding the best global solutions. We revised the CSO strategy in our proposed scheme to make it practicable and suitable to solve the mentioned problem. The experimental results show that the proposed scheme can obtain a better solution with less computation time. [Copyright &y& Elsevier]

Abstract: Certificateless signcryption is a useful primitive which simultaneously provides the functionalities of certificateless encryption and certificateless signature. Recently, Liu et al. proposed a new certificateless signcryption scheme, and claimed that their scheme is provably secure without random oracles in a strengthened security model, where the malicious-but-passive KGC attack is considered. Unfortunately, by giving concrete attacks, we indicate that Liu et al. certificateless signcryption scheme is not secure in this strengthened security model. [ABSTRACT FROM AUTHOR]

Abstract: The security of traditional identity-based signatures wholly depends on the security of secret keys. Exposure of secret keys requires reissuing all previously assigned signatures. This limitation becomes more obvious today as key exposure is more common with increasing use of mobile and unprotected devices. Under this background, mitigating the damage of key exposure in identity-based signatures is an important problem. To deal with this problem, we propose to integrate forward security into identity-based signatures. In this paper, we firstly formalize the definition and security notions for forward-secure identity-based signature scheme, and then construct an efficient scheme. All parameters in our scheme have, at most, log-squared complexity in terms of the total number of time periods. The scheme is provably secure without random oracles. [ABSTRACT FROM AUTHOR]

Abstract: The present paper proposes a digital image watermarking scheme using the characteristics of the human visual system (HVS), spread transform technique and statistical information measure. Spread transform (ST) scheme is implemented using the transform coefficients of both the host and the watermark signal. Watermark embedding strength is adaptively adjusted using frequency sensitivity, luminance, contrast and entropy masking of HVS model. The choice of Hadamard transform as watermark embedding domain offers several advantages, such as low loss in image information (higher image fidelity), greater reliability of watermark detection and higher data hiding capacity at high degree of compression. Performance of the proposed method is compared with a number of recently reported watermarking schemes based on spread spectrum (SS) and quantization index modulation (QIM). [ABSTRACT FROM AUTHOR]

Abstract: We propose a new generic construction for signcryption and show that it is secure under the security models which are comparable to the security against adaptive chosen ciphertext attacks for public key encryption and the existential unforgeability against chosen message attacks for signature. In particular, the security models also capture the notion of insider security. The generic construction relies on the existence of a special class of efficient public key encryption schemes which allow the encryption randomness to be recovered during decryption. We also propose two efficient instantiations for the generic construction and show that one of them has less message expansion and yields smaller ciphertext when compared with all the existing signcryption schemes. [Copyright &y& Elsevier]

Abstract: Mobile agents can migrate across different execution environments through the network. One important task of a mobile agent is to act as a proxy signer to sign a digital signature on behalf of the agent owner. As the agent and the remote hosts are not trustworthy, or are probably malicious, there are great challenges for the task. In this paper, we propose an efficient, secure threshold proxy signature scheme based on the RSA cryptosystem. The proposed scheme shares the proxy signing key with a simple Lagrange formula. However, it does not reveal any secret information. Owing to its simple algorithm and few parameter requirements, the proposed scheme requires few calculations and few transactions. The proxy signature generation stage and the proxy signature combining stage are completely non-interactive. Furthermore, the size of the partial proxy signing key and that of the partial proxy signature are constant and independent of the number of proxy signers. [Copyright &y& Elsevier]

Abstract: This work concerns the tracking problem of uncertain Takagi–Sugeno (T–S) continuous fuzzy model with external disturbances. The objective is to get a model reference based output feedback tracking control law. The control scheme is based on a PDC structure, a fuzzy observer and a H ∞ performance to attenuate the external disturbances. The stability of the whole closed-loop model is investigated using the well-known quadratic Lyapunov function. The key point of the proposed approaches is to achieve conditions under a LMI (linear matrix inequalities) formulation in the case of an uncertain and disturbed T–S fuzzy model. This formulation facilitates obtaining solutions through interior point optimization methods for some nonlinear output tracking control problems. Finally, a simulation is provided on the well-known inverted pendulum testbed to show the efficiency of the proposed approach. [Copyright &y& Elsevier]