Biblio

Medical organizations find it challenging to adopt cloud-based Electronic Health Records (EHR) services due to the risk of data breaches and the resulting compromise of patient data. Existing authorization models follow a patient-centric approach for EHR management, where the responsibility of authorizing data access is handled at the patients’ end. This creates significant overhead for the patient, who must authorize every access of their health record. It is also not practical given that multiple personnel are typically involved in providing care and that the patient may not always be in a state to provide this authorization.

The Internet of Things (IoT) is enabling a new generation of innovative services based on the seamless integration of smart objects into information systems. Such IoT devices generate an uninterrupted flow of information that can be transmitted through an untrusted network and stored on an untrusted infrastructure. The latter raises new security and privacy challenges that require novel cryptographic methods. Attribute-Based Encryption (ABE) is a new type of public-key encryption that enforces a fine-grained access control on encrypted data based on flexible access policies. The feasibility of ABE adoption in fully-fledged computing systems, i.e. smartphones or embedded systems, has been demonstrated in recent works. In this paper we assess the feasibility of the adoption of ABE in typical IoT constrained devices, characterized by limited capabilities in terms of computing, storage and power. Specifically, an implementation of three ABE schemes for ESP32, a low-cost popular platform to deploy IoT devices, is developed and evaluated in terms of encryption/decryption time and energy consumption. The performance evaluation shows that the adoption of ABE on constrained devices is feasible, although it has a cost that increases with the number of attributes. The analysis in particular highlights how ABE has a significant impact in the lifetime of battery-powered devices, which is impaired significantly when a high number of attributes is adopted.

Media streaming has largely dominated the Internet traffic and the trend will keep increasing in the next years. To efficiently distribute the media content, Information-Centric Networking (ICN) has attracted many researchers. Since end users usually obtain content from indeterminate caches in ICN, the publisher cannot reinforce data security and access control depending on the caches. Hence, the ability of self-contained protection is important for the cached contents. Attribute-based encryption (ABE) is considered the preferred solution to achieve this goal. However, the existing ABE schemes usually have problems regarding efficiency. The exponentiation in key generation and pairing operation in decryption respectively increases linearly with the number of attributes involved, which make it costly. In this paper, we propose an efficient key-policy ABE with fast key generation and decryption (FKP-ABE). In the key generation, we get rid of exponentiation and only require multiplications/divisions for each attribute in the access policy. And in the decryption, we reduce the pairing operations to a constant number, no matter how many attributes are used. The efficiency analysis indicates that our scheme has better performance than the existing KP-ABE schemes. Finally, we present an implementation framework that incorporates the proposed FKP-ABE with the ICN architecture.

In many hostile military environments for instance war zone, unfriendly nature, etc., the systems perform on the specially promoted mode and nature which they tolerate the defined system network architecture. Preparation of Disruption-Tolerant systems (DTN) enhances the network between the remote devices which provided to the soldiers in the war zone, this situation conveys the reliable data transmission under scanner. Cipher text approach are based on the attribute based encryption which mainly acts on the attributes or role of the users, which is a successful cryptographic strategy to maintain the control issues and also allow reliable data transfer. Specially, the systems are not centralized and have more data constrained issues in the systems, implementing the Ciphertext-Policy Attribute-Based Encryption (CP-ABE) was an important issue, where this strategy provides the new security and data protection approach with the help of the Key Revocation, Key Escrows and collaboration of the certain attributes with help of main Key Authorities. This paper mainly concentrates on the reliable data retrieval system with the help of CP-ABE for the Disruption-Tolerant Networks where multiple key authorities deal with respective attributes safely and securely. We performed comparison analysis on existing schemes with the recommended system components which are configured in the respective decentralized tolerant military system for reliable data retrieval.

While the Internet of Things (IoT) is embraced as important tools for efficiency and productivity, it is becoming an increasingly attractive target for cybercriminals. This work represents the first endeavor to develop practical Puncturable Attribute Based Encryption schemes that are light-weight and applicable in IoTs. In the proposed scheme, the attribute-based encryption is adopted for fine grained access control. The secret keys are puncturable to revoke the decryption capability for selected messages, recipients, or time periods, thus protecting selected important messages even if the current key is compromised. In contrast to conventional forward encryption, a distinguishing merit of the proposed approach is that the recipients can update their keys by themselves without key re-issuing from the key distributor. It does not require frequent communications between IoT devices and the key distribution center, neither does it need deleting components to expunge existing keys to produce a new key. Moreover, we devise a novel approach which efficiently integrates attribute-based key and punctured keys such that the key size is roughly the same as that of the original attribute-based encryption. We prove the correctness of the proposed scheme and its security under the Decisional Bilinear Diffie-Hellman (DBDH) assumption. We also implement the proposed scheme on Raspberry Pi and observe that the computation efficiency of the proposed approach is comparable to the original attribute-based encryption. Both encryption and decryption can be completed within tens of milliseconds.

Medical organizations find it challenging to adopt cloud-based electronic medical records services, due to the risk of data breaches and the resulting compromise of patient data. Existing authorization models follow a patient centric approach for EHR management where the responsibility of authorizing data access is handled at the patients' end. This however creates a significant overhead for the patient who has to authorize every access of their health record. This is not practical given the multiple personnel involved in providing care and that at times the patient may not be in a state to provide this authorization. Hence there is a need of developing a proper authorization delegation mechanism for safe, secure and easy cloud-based EHR management. We have developed a novel, centralized, attribute based authorization mechanism that uses Attribute Based Encryption (ABE) and allows for delegated secure access of patient records. This mechanism transfers the service management overhead from the patient to the medical organization and allows easy delegation of cloud-based EHR's access authority to the medical providers. In this paper, we describe this novel ABE approach as well as the prototype system that we have created to illustrate it.

In recent years, many users have uploaded data to the cloud for easy storage and sharing with other users. At the same time, security and privacy concerns for the data are growing. Attribute-based encryption (ABE) enables both data security and access control by defining users with attributes so that only those users who have matching attributes can decrypt them. For real-world applications of ABE, revocation of users or their attributes is necessary so that revoked users can no longer decrypt the data. In actual implementations, ABE is used in hybrid with a symmetric encryption scheme such as the advanced encryption standard (AES) where data is encrypted with AES and the AES key is encrypted with ABE. The hybrid encryption scheme requires re-encryption of the data upon revocation to ensure that the revoked users can no longer decrypt that data. To re-encrypt the data, the data owner (DO) must download the data from the cloud, then decrypt, encrypt, and upload the data back to the cloud, resulting in both huge communication costs and computational burden on the DO depending on the size of the data to be re-encrypted. In this paper, we propose an attribute-based proxy re-encryption method in which data can be re-encrypted in the cloud without downloading any data by adopting both ABE and Syalim's encryption scheme. Our proposed scheme reduces the communication cost between the DO and cloud storage. Experimental results show that the proposed method reduces the communication cost by as much as one quarter compared to that of the trivial solution.

Most centralized systems allow data access to its cloud user if a cloud user has a certain set of satisfying attributes. Presently, one method to compete such policies is to use an authorized cloud server to maintain the user data and have access control over it. At times, when one of the servers keeping data is compromised, the security of the user data is compromised. For getting access control, maintaining data security and obtaining precise computing results, the data owners have to keep attribute-based security to encrypt the stored data. During the delegation of data on cloud, the cloud servers may be tampered by the counterfeit cipher-text. Furthermore, the authorized users may be cheated by retorting them that they are unauthorized. Largely the encryption control access attribute policies are complex. In this paper, we present Cipher-text Policy Attribute-Based Encryption for maintaining complex access control over encrypted data with verifiable customizable authorization. The proposed technique provides data confidentiality to the encrypted data even if the storage server is comprised. Moreover, our method is highly secured against collusion attacks. In advance, performance evaluation of the proposed system is elaborated with implementation of the same.

Attribute-Based Access Control (ABAC), a promising alternative to traditional models of access control, has gained significant attention in recent academic literature. This attention has lead to the creation of a number of ABAC models including our previous contribution, Hierarchical Group and Attribute-Based Access Control (HGABAC). However, to date few complete solutions exist that provide both an ABAC model and architecture that could be implemented in real life scenarios. This work aims to advance progress towards a complete ABAC solution by introducing Hierarchical Group Attribute Architecture (HGAA), an architecture to support HGABAC and close the gap between a model and real world implementation. In addition to HGAA we also present an attribute certificate specification that enables users to provide proof of attribute ownership in a pseudonymous and off-line manner, as well as an update to the Hierarchical Group Policy Language (HGPL) to support our namespace for uniquely identifying attributes across disparate security domains. Details of our HGAA implementation are given and a preliminary analysis of its performance is discussed as well as directions for future work.

Inner-product encryption (IPE) is a well-known functional encryption primitive that allows decryption when the inner-product of the attribute vectors, upon which the encrypted data and the decryption key depend, is equal to zero. Using IPE, it is possible to define fine-grained access policies over encrypted data whose enforcement can be outsourced to the cloud where the data are stored. However, current IPE schemes do not support efficient access policy changes. In this paper, we propose an efficient inner-product proxy re-encryption (E-IPPRE) scheme that provides the proxy server with a transformation key, with which a ciphertext associated with an attribute vector can be transformed to a new ciphertext associated with a different attribute vector, providing a policy update mechanism with a performance suitable for many practical applications. We experimentally assess the efficiency of our protocol and show that it is selective attribute-secure against chosen-plaintext attacks in the standard model under the Asymmetric Decisional Bilinear Diffie-Hellman assumption.

We report on our implementation of a new Gaussian sampling algorithm for lattice trapdoors. Lattice trapdoors are used in a wide array of lattice-based cryptographic schemes including digital signatures, attributed-based encryption, program obfuscation and others. Our implementation provides Gaussian sampling for trapdoor lattices with prime moduli, and supports both single- and multi-threaded execution. We experimentally evaluate our implementation through its use in the GPV hash-and-sign digital signature scheme as a benchmark. We compare our design and implementation with prior work reported in the literature. The evaluation shows that our implementation 1) has smaller space requirements and faster runtime, 2) does not require multi-precision floating-point arithmetic, and 3) can be used for a broader range of cryptographic primitives than previous implementations.

Searchable encryption is one of the most important techniques for the sensitive data outsourced to cloud server, and has been widely used in cloud storage which brings huge convenience and saves bandwidth and computing resources. A novel searchable cryptographic scheme is proposed by which data owner can control the search and use of the outsourced encrypted data according to its access control policy. The scheme is called searchable ciphertext-policy attribute-based encryption with multikeywords (CPABMKS). In the scheme, CP-ABE and keywords are combined together through the way that the keywords are regarded as the file attributes. To overcome the previous problems in cloud storage, access structures are hidden so that receivers cannot extract sensitive information from the ciphertext. At the same time, this scheme supports the multi-keywords search, and the data owner can outsource the encryption operations to the private cloud that can reduce the data owner' calculation. The security of this scheme is proved based on the DBDH assumption. Finally, scheme evaluation shows that the CPABMKS scheme is practical

Attributes-based encryption (ABE) is a promising cryptographic mechanism that provides a fine-grained access control for cloud environment. Since most of the parties exchange sensitive data among them by using cloud computing, data protection is very important for data confidentiality. Ciphertext policy attributes-based encryption (CP-ABE) is one of the ABE schemes, which performs an access control of security mechanisms for data protection in cloud storage. In CP-ABE, each user has a set of attributes and data encryption is associated with an access policy. The secret key of a user and the ciphertext are dependent upon attributes. A user is able to decrypt a ciphertext if and only if his attributes satisfy the access structure in the ciphertext. The practical applications of CP-ABE have still requirements for attributes policy management and user revocation. This paper proposed an important issue of policy revocation in CP-ABE scheme. In this paper, sensitive parts of personal health records (PHRs) are encrypted with the help of CP-ABE. In addition, policy revocation is considered to add in CP-ABE and generates a new secret key for authorized users. In proposed attributes based encryption scheme, PHRs owner changes attributes policy to update authorized user lists. When policy revocation occurs in proposed PHRs sharing system, a trusted authority (TA) calculates a partial secret token key according to a policy updating level and then issues new or updated secret keys for new policy. Proposed scheme emphasizes on key management, policy management and user revocation. It provides a full control on data owner according to a policy updating level what he chooses. It helps both PHRs owner and users for flexible policy revocation in CP-ABE without time consuming.

Personal health records (PHR) are an emerging health information exchange model, which facilitates PHR owners to efficiently manage their health data. Typically, PHRs are outsourced and stored in third-party cloud platforms. Although, outsourcing private health data to third-party platforms is an appealing solution for PHR owners, it may lead to significant privacy concerns, because there is a higher risk of leaking private data to unauthorized parties. As a way of ensuring PHR owners' control of their outsourced PHR data, attribute based encryption (ABE) mechanisms have been considered due to the fact that such schemes facilitate a mechanism of sharing encrypted data among a set of intended recipients. However, such existing PHR solutions suffer from inflexibility and scalability issues due to the limitations associated with the adopted ABE mechanisms. To address these issues, we propose a distributed multi-authority ABE scheme and thereby we show how a patient-centric, attribute based PHR sharing scheme which can provide flexible access for both professional users such as doctors as well as personal users such as family and friends is realized. We have shown that the proposed scheme supports on-demand user revocation as well as secure under standard security assumptions. In addition, the simulation results provide evidence for the fact that our scheme can function efficiently in practice. Furthermore, we have shown that the proposed scheme can cater the access requirements associated with distributed multiuser PHR sharing environments as well as more realistic and scalable compared with similar existing PHR sharing schemes.

Data outsourcing in cloud is emerging as a successful paradigm that benefits organizations and enterprises with high-performance, low-cost, scalable data storage and sharing services. However, this paradigm also brings forth new challenges for data confidentiality because the outsourced are not under the physic control of the data owners. The existing schemes to achieve the security and usability goal usually apply encryption to the data before outsourcing them to the storage service providers (SSP), and disclose the decryption keys only to authorized user. They cannot ensure the security of data while operating data in cloud where the third-party services are usually semi-trustworthy, and need lots of time to deal with the data. We construct a privacy data management system appending hierarchical access control called HAC-DMS, which can not only assure security but also save plenty of time when updating data in cloud.

The development of cloud computing has brought a lot of advantages, such as reducing the hardware cost and a more convenient storage solution. Because of the convenient and cheap storage solution, a large number of users put their valuable data onto the cloud. There have been more and more outsourcing data security and privacy issues. Several schemes using attribute-based encryption (ABE) have been proposed in cloud computing outsourcing data access control; However, most of them have stubborn in complex access control policy. To implement scalable, flexible and fine-grained access control in cloud storage, this paper proposes an attribute-based solution with time restriction delegate by extending the Ciphertext-policy attribute-based encryption (CP-ABE). This scheme not only realizes the scalability and fine-grained access control, but also gives a solution for the data delegate. Our delegate mechanism can let the users entrusted the data which in their visit range to others, and the ability to set a time limit. Finally, we prove the security of our scheme based on the security of the Ciphertext-policy attribute-based encryption (CP-ABE) by Bethencourt et al. and analyze its performance and computational complexity. Experiments for our scheme are implemented and the result shows that it is both efficient and flexible in dealing with access control for outsourced data in cloud computing.

With data becoming available in larger quantities and at higher rates, new data processing paradigms have been proposed to handle high-volume, fast-moving data. Data Stream Processing is one such paradigm wherein transient data streams flow through sets of continuous queries, only returning results when data is of interest to the querier. To avoid the large costs associated with maintaining the infrastructure required for processing these data streams, many companies will outsource their computation to third-party cloud services. This outsourcing, however, can lead to private data being accessed by parties that a data provider may not trust. The literature offers solutions to this confidentiality and access control problem but they have fallen short of providing a complete solution to these problems, due to either immense overheads or trust requirements placed on these third-party services. To address these issues, we have developed PolyStream, an enhancement to existing data stream management systems that enables data providers to specify attribute-based access control policies that are cryptographically enforced while simultaneously allowing many types of in-network data processing. We detail the access control models and mechanisms used by PolyStream, and describe a novel use of security punctuations that enables flexible, online policy management and key distribution. We detail how queries are submitted and executed using an unmodified Data Stream Management System, and show through an extensive evaluation that PolyStream yields a 550x performance gain versus the state-of-the-art system StreamForce in CODASPY 2014, while providing greater functionality to the querier.

Attribute-based methods provide authorization to parties based on whether their set of attributes (e.g., age, organization, etc.) fulfills a policy. In attribute-based encryption (ABE), authorized parties can decrypt, and in attribute-based credentials (ABCs), authorized parties can authenticate themselves. In this paper, we combine elements of ABE and ABCs together with garbled circuits to construct attribute-based key exchange (ABKE). Our focus is on an interactive solution involving a client that holds a certificate (issued by an authority) vouching for that client's attributes and a server that holds a policy computable on such a set of attributes. The goal is for the server to establish a shared key with the client but only if the client's certified attributes satisfy the policy. Our solution enjoys strong privacy guarantees for both the client and the server, including attribute privacy and unlinkability of client sessions. Our main contribution is a construction of ABKE for arbitrary circuits with high (concrete) efficiency. Specifically, we support general policies expressible as boolean circuits computed on a set of attributes. Even for policies containing hundreds of thousands of gates the performance cost is dominated by two pairing computations per policy input. Put another way, for a similar cost to prior ABE/ABC solutions, which can only support small formulas efficiently, we can support vastly richer policies. We implemented our solution and report on its performance. For policies with 100,000 gates and 200 inputs over a realistic network, the server and client spend 957 ms and 176 ms on computation, respectively. When using offline preprocessing and batch signature verification, this drops to only 243 ms and 97 ms.

Big data is the next frontier for modernization, rivalry, and profitability. It is the foundation of all the major trends such as social networks, mobile devices, healthcare, stock markets etc. Big data is efficiently stored in the cloud because of its high-volume, high-speed and high-assortment data resources. An unauthorized user access control is the gravest threat of huge information in the cloud environment because of the remote file storage. Attribute Based Encryption (ABE) is an efficient access control procedure to guarantee end-to-end security for huge information in the cloud. Most often existing ABE working principle is based on bilinear pairing. In this paper, we construct a peculiar ABE for big data in the cloud. Our proposed scheme is based on quadratic residue and attribute union which is based on fundamental arithmetic theorem.

In ciphertext policy attribute-based encryption scheme, access policies are associated with ciphertext and tied to it. It is necessary to hide the access policy in the most sensitive spots such as political, medical and economic fields, that is, receiver's anonymity. In this paper, we propose an efficient CP-ABE construction with hidden policy and prove it to be fully secure under static assumptions applying the dual system encryption methodology. Access structures in our construction are AND gates on positive, negative and wildcard attributes and the ciphertext size is short, which is only concerned with the number of wildcards.

In cloud computing, computationally weak users are always willing to outsource costly computations to a cloud, and at the same time they need to check the correctness of the result provided by the cloud. Such activities motivate the occurrence of verifiable computation (VC). Recently, Parno, Raykova and Vaikuntanathan showed any VC protocol can be constructed from an attribute-based encryption (ABE) scheme for a same class of functions. In this paper, we propose two practical and efficient semi-adaptively secure key-policy attribute-based encryption (KP-ABE) schemes with constant-size ciphertexts. The semi-adaptive security requires that the adversary designates the challenge attribute set after it receives public parameters but before it issues any secret key query, which is stronger than selective security guarantee. Our first construction deals with small universe while the second one supports large universe. Both constructions employ the technique underlying the prime-order instantiation of nested dual system groups, which are based on the \$d\$-linear assumption including SXDH and DLIN assumptions. In order to evaluate the performance, we implement our ABE schemes using \$\textbackslashtextsf\Python\\$ language in Charm. Compared with previous KP-ABE schemes with constant-size ciphertexts, our constructions achieve shorter ciphertext and secret key sizes, and require low computation costs, especially under the SXDH assumption.

Secure Data Sharing (SDS) enables users to share data in the cloud in a confidential and integrity-preserving manner. Many recent SDS approaches are based on Attribute-Based Encryption (ABE), leveraging the advantage that ABE allows to address a multitude of users with only one ciphertext. However, ABE approaches often come with the downside that they require a central fully-trusted entity that is able to decrypt any ciphertext in the system. In this paper, we investigate on whether ABE could be used to efficiently implement Decentralized Secure Data Sharing (D-SDS), which explicitly demands that the authorization and access control enforcement is carried out solely by the owner of the data, without the help of a fully-trusted third party. For this purpose, we did a comprehensive analysis of recent ABE approaches with regard to D-SDS requirements. We found one ABE approach to be suitable, and we show different alternatives to employ this ABE approach in a group-based D-SDS scenario. For a realistic estimation of the resource consumption, we give concrete resource consumption values for workloads taken from real-world system traces and exemplary up-to-date mobile devices. Our results indicate that for the most D-SDS operations, the resulting computation times and outgoing network traffic will be acceptable in many use cases. However, the computation times and outgoing traffic for the management of large groups might prevent using mobile devices.

We study a sensor network setting in which samples are encrypted individually using different keys and maintained on a cloud storage. For large systems, e.g. those that generate several millions of samples per day, fine-grained sharing of encrypted samples is challenging. Existing solutions, such as Attribute-Based Encryption (ABE) and Key Aggregation Cryptosystem (KAC), can be utilized to address the challenge, but only to a certain extent. They are often computationally expensive and thus unlikely to operate at scale. We propose an algorithmic enhancement and two heuristics to improve KAC's key reconstruction cost, while preserving its provable security. The improvement is particularly significant for range and down-sampling queries – accelerating the reconstruction cost from quadratic to linear running time. Experimental study shows that for queries of size 32k samples, the proposed fast reconstruction techniques speed-up the original KAC by at least 90 times on range and down-sampling queries, and by eight times on general (arbitrary) queries. It also shows that at the expense of splitting the query into 16 sub-queries and correspondingly issuing that number of different aggregated keys, reconstruction time can be reduced by 19 times. As such, the proposed techniques make KAC more applicable in practical scenarios such as sensor networks or the Internet of Things.

Recently, various protocols have been proposed for securely outsourcing database storage to a third party server, ranging from systems with "full-fledged" security based on strong cryptographic primitives such as fully homomorphic encryption or oblivious RAM, to more practical implementations based on searchable symmetric encryption or even on deterministic and order-preserving encryption. On the flip side, various attacks have emerged that show that for some of these protocols confidentiality of the data can be compromised, usually given certain auxiliary information. We take a step back and identify a need for a formal understanding of the inherent efficiency/privacy trade-off in outsourced database systems, independent of the details of the system. We propose abstract models that capture secure outsourced storage systems in sufficient generality, and identify two basic sources of leakage, namely access pattern and ommunication volume. We use our models to distinguish certain classes of outsourced database systems that have been proposed, and deduce that all of them exhibit at least one of these leakage sources. We then develop generic reconstruction attacks on any system supporting range queries where either access pattern or communication volume is leaked. These attacks are in a rather weak passive adversarial model, where the untrusted server knows only the underlying query distribution. In particular, to perform our attack the server need not have any prior knowledge about the data, and need not know any of the issued queries nor their results. Yet, the server can reconstruct the secret attribute of every record in the database after about \$Ntextasciicircum4\$ queries, where N is the domain size. We provide a matching lower bound showing that our attacks are essentially optimal. Our reconstruction attacks using communication volume apply even to systems based on homomorphic encryption or oblivious RAM in the natural way. Finally, we provide experimental results demonstrating the efficacy of our attacks on real datasets with a variety of different features. On all these datasets, after the required number of queries our attacks successfully recovered the secret attributes of every record in at most a few seconds.

Funded under the European Union's Horizon 2020 research and innovation programme, SAFEcrypto will provide a new generation of practical, robust and physically secure post-quantum cryptographic solutions that ensure long-term security for future ICT systems, services and applications. The project will focus on the remarkably versatile field of Lattice-based cryptography as the source of computational hardness, and will deliver optimised public key security primitives for digital signatures and authentication, as well identity based encryption (IBE) and attribute based encryption (ABE). This will involve algorithmic and design optimisations, and implementations of lattice-based cryptographic schemes addressing cost, energy consumption, performance and physical robustness. As the National Institute of Standards and Technology (NIST) prepares for the transition to a post-quantum cryptographic suite B, urging organisations that build systems and infrastructures that require long-term security to consider this transition in architectural designs; the SAFEcrypto project will provide Proof-of-concept demonstrators of schemes for three practical real-world case studies with long-term security requirements, in the application areas of satellite communications, network security and cloud. The goal is to affirm Lattice-based cryptography as an effective replacement for traditional number-theoretic public-key cryptography, by demonstrating that it can address the needs of resource-constrained embedded applications, such as mobile and battery-operated devices, and of real-time high performance applications for cloud and network management infrastructures.