Bilinear Groups Research Articles

Verifiable secret sharing scheme without dealer based on vector space access structures over bilinear groups

In general, most of the previous secret sharing schemes involve a secret dealer and a number of participants. The dealer generates a secret and then distributes the secret shares to the participants in a centralised manner, which may lead to the data tamper problem. A verifiable secret sharing scheme without dealer on vector space access structures over bilinear groups is presented. In particular, each participant can act as a ‘dealer’ and the secret in the proposed scheme is a random element generated by all the participants from a bilinear group. In addition, the performance of the proposed scheme in terms of security and computing complexity is analysed in detail and compared it with that of the scheme by Zhang and Zhang. The results show that the proposed scheme performs better in terms of computational cost.

Efficient Leakage-Resilient Authenticated Key Agreement Protocol in the Continual Leakage eCK Model

Based on users’ permanent private keys and ephemeral secret keys (randomness secret values), authenticated key agreement (AKA) protocols are used to construct a common session key between two session parties while authenticating each other. Recently, the design of leakage-resilient AKA (LR-AKA) resisting side-channel attacks has received significant attention from researchers. By side-channel attacks, an adversary is allowed to obtain fractional leakage information of private (secret) keys during the computation rounds of LR-AKA protocols. However, most LR-AKA protocols have a restriction, namely, the overall fractional leakage information must be bounded. In this paper, we propose an efficient LR-AKA protocol with overall unbounded leakage property in the continual leakage extended Canetti-Krawczyk model. Security analysis is given to demonstrate that our LR-AKA protocol is provably secure in the generic bilinear group model. By comparisons, our protocol is better than the previously proposed LR-AKA protocols in terms of computation cost, security model, and leakage properties.

Outsourced Ciphertext-Policy based Privacy Preservation for Mobile Cloud Computing

With the rapid advancement of mobile phone technology, crowdsourced mobile applications are gaining importance for cheaper and abundant information gathering source. A couple of benefits of crowdsourcing are better (versatile) and less expensive responses to the requester, source of earning for crowd contributors at the same time. With the emergence of wireless access technologies and the popularity of smart and intelligent mobile terminals like smartphones, the privacy of requesters and contributors in a crowdsourced environment is becoming more crucial. Computation complexity of available privacy preserving tools and verification of outsourced schemes are not feasible for WSNs low power and resource constrained contributing devices. The low-end resource constrained mobile devices to have less capability to compute multiple access policies and the computation cost increases with the complexity of access strategy. To resolve this issue, we proposed a resourceful verifiable outsourced encryption policy based on ciphertext attributed policy (OS-ABE), which is a platform for computing exhaustive computing tasks during private data encryption and decryption. The proposed scheme works without revealing the personal data at outsource and leaves only the minimal calculation to the crowdsource contributor and the requester. To authenticate and overcome known attacks like DoS, false computing results at crowdsourced platforms, anonymity server is embedded to handle contributors privacy issues by providing a secure shell in the framework. This scheme is based on bilinear group of prime order in which two hash functions can verify outsourced computation and ensure integrity of data. The formal security and performance analysis is presented and found to be efficient and secure.

Improving Privacy and Security in Decentralizing Multi-Authority Attribute-Based Encryption in Cloud Computing

Decentralizing multi-authority attribute-based encryption (ABE) has been adopted for solving problems arising from sharing confidential corporate data in cloud computing. For decentralizing multi-authority ABE systems that do not rely on a central authority, collusion resistance can be achieved using a global identifier. Therefore, identity needs to be managed globally, which results in the crucial problems of privacy and security. A scheme is developed that does not use a central authority to manage users and keys, and only simple trust relations need to be formed by sharing the public key between each attribute authority (AA). User identities are unique by combining a user’s identity with the identity of the AA where the user is located. Once a key request needs to be made to an authority outside the domain, the request needs to be performed by the authority in the current domain rather than by the users, so, user identities remain private to the AA outside the domain, which will enhance privacy and security. In addition, the key issuing protocol between AA is simple as the result of the trust relationship of AA. Moreover, extensibility for authorities is also supported by the scheme presented in this paper. The scheme is based on composite order bilinear groups. A proof of security is presented that uses the dual system encryption methodology.

Efficient leakage-resilient blind and partially blind signatures

The techniques of the blind and partially blind signatures play an important role in numerous applications, most prominently in electronic voting and electronic cash. In this paper, we first present formal definitions of leakage-resilient blind and partially blind signatures. Subsequently, we propose an efficient leakage-resilient blind signature scheme and an efficient leakage-resilient partially blind signature scheme in the continual leakage model. The proposed leakage-resilient blind signature scheme is the first protocol which is secure even in a setting where the adversary may obtain leakage information on the signer's or user's internal state, including secret key and the randomness. However, in the only known leakage-resilient blind signature scheme which was proposed by Rückert, the adversary is given the leakage information only about the signer's secret key. The proposed partially blind signature scheme is the first leakage-resilient partially blind signature scheme. Also, we analyse their security and efficiency in the generic bilinear group model.

Efficient leakage-resilient blind and partially blind signatures

The techniques of the blind and partially blind signatures play an important role in numerous applications, most prominently in electronic voting and electronic cash. In this paper, we first present formal definitions of leakage-resilient blind and partially blind signatures. Subsequently, we propose an efficient leakage-resilient blind signature scheme and an efficient leakage-resilient partially blind signature scheme in the continual leakage model. The proposed leakage-resilient blind signature scheme is the first protocol which is secure even in a setting where the adversary may obtain leakage information on the signer's or user's internal state, including secret key and the randomness. However, in the only known leakage-resilient blind signature scheme which was proposed by Ruckert, the adversary is given the leakage information only about the signer's secret key. The proposed partially blind signature scheme is the first leakage-resilient partially blind signature scheme. Also, we analyse their security and efficiency in the generic bilinear group model.

Homomorphic signatures with sublinear public keys via asymmetric programmable hash functions

We introduce the notion of asymmetric programmable hash functions (APHFs, for short), which adapts Programmable hash functions, introduced by Hofheinz and Kiltz (Crypto 2008, Springer, 2008), with two main differences. First, an APHF works over bilinear groups, and it is asymmetric in the sense that, while only secretly computable, it admits an isomorphic copy which is publicly computable. Second, in addition to the usual programmability, APHFs may have an alternative property that we call programmable pseudorandomness. In a nutshell, this property states that it is possible to embed a pseudorandom value as part of the function’s output, akin to a random oracle. In spite of the apparent limitation of being only secretly computable, APHFs turn out to be surprisingly powerful objects. We show that they can be used to generically implement both regular and linearly-homomorphic signature schemes in a simple and elegant way. More importantly, when instantiating these generic constructions with our concrete realizations of APHFs, we obtain: (1) the first linearly-homomorphic signature (in the standard model) whose public key is sub-linear in both the dataset size and the dimension of the signed vectors; (2) short signatures (in the standard model) whose public key is shorter than those by Hofheinz–Jager–Kiltz (Asiacrypt 2011, Springer, 2011) and essentially the same as those by Yamada et al. (CT-RSA 2012, Springer, 2012).

Cost-Effective and Scalable Data Sharing in Cloud Storage Using Hierarchical Attribute-Based Encryption with Forward Security

Cloud storage greatly facilitates both individuals and organizations to share data over the Internet. However, there are several security issues that impede to outsource their data. Among various approaches introduced to overcome these issues, attribute-based encryption (ABE) provides secure and flexible access control on shared data, and thus is rather promising. But the original ABE is not adaptable to some special circumstances, where attributes are organized in a hierarchical structure, such as enterprises and official institutions. On the other hand, although the wide use of mobile devices enables users to conveniently access shared data anywhere and anytime, this also increases the risk of key exposure, which will result into unwanted exposure of the shared data. In this paper, we extend the functionality of the original ABE and enhance its security by providing key generation delegation and forward security. Consequently, the enhanced ABE meets applications of large organizations with hierarchies and minimizes the damage in the case of unexpected key exposures. Specifically speaking, we present a forward-secure ciphertext-policy hierarchical attribute-based encryption scheme in prime order bilinear groups, as a core building of attribute-based data sharing scheme. The security of the proposed scheme is proven in the standard model. We conduct experiments to demonstrate its efficiency and practicability.

Attribute-based Encryption with Non-Monotonic Access Structures Supporting Fine-Grained Attribute Revocation in M-healthcare.

By sharing the personal health information (PHI) in the healthcare provider (HP) which is equipped with cloud servers, mobile-healthcare (m-healthcare) significantly promotes a huge revolution of medical consultation. Nonetheless there is a series of challenges such as PHI confidentiality and the attribute revocation. To deal with these problems, we propose a scheme based on the attribute-based encryption. The scheme which supports non-monotonic access structures and fine-grained attribute revocation is established over the composite order bilinear groups. By utilizing this scheme, we can well protect PHI and achieve the goal of revocation. Furthermore, the security analysis and comparison show that our scheme is more expressive despite of the lower efficiency.

Leakage-resilient attribute based encryption in prime-order groups via predicate encodings

Recently, leakage-resilient cryptography has become a hot research topic. It seeks to build more robust models of adversarial access to cryptographic algorithms. The main goal is to design a scheme that remains secure even when arbitrary, yet bounded, information about secret key is leaked. In this paper, we present a modular framework for designing leakage-resilient attribute-based encryption (ABE) schemes based on extended predicate encoding. We first extend the predicate encoding to the leakage-resilient predicate encoding; and then, design several leakage-resilient predicate encodings, and finally give a generic construction of leakage-resilient ABE based on the newly proposed encodings. Moreover, we can instantiate our framework in prime order bilinear groups to obtain concrete constructions, and prove their full security under the standard k-Lin assumption in the continual memory leakage model.

Efficient large-universe multi-authority ciphertext-policy attribute-based encryption with white-box traceability

Traceable multi-authority ciphertext-policy attribute-based encryption (CP-ABE) is a practical encryption method that can achieve user traceability and fine-grained access control simultaneously. However, existing traceable multi-authority CP-ABE schemes have two main limitations that prevent them from practical applications. First, these schemes only support small universe: the attributes must be fixed at system setup and the attribute space is restricted to polynomial size. Second, the schemes are either less expressive (the access policy is limited to “AND gates with wildcard) or inefficient (the system is constructed in composite order bilinear groups). To address these limitations, we present a traceable large universe multi-authority CP-ABE scheme, and further prove that it is statically secure in the random oracle model. Compared with existing traceable multi-authority CP-ABE schemes, the proposed scheme has four advantages. First, the attributes are not fixed at setup and the attribute universe is not bounded to polynomial size. Second, the ciphertext polices can be expressed as any monotone access structures. Third, the proposed scheme is constructed in prime order groups, which makes this scheme more efficient than those in composite order bilinear groups. Finally, the proposed scheme requires neither a central authority nor an identity table for tracing.

Verifiable keyword search over encrypted cloud data in smart city

In smart city, which integrates the Information and Communication Technologies (ICT) including cloud computing and internet of things, all kinds of data collected by smart devices help to make everything intelligent. Through outsourcing encrypted data to cloud server, data owners can reduce the high storage and computational burden on resources-constrained smart devices. To further avoid the semi-honest-but-curious cloud server returning a fraction of false search results, this paper proposes a verifiable attribute-based keyword search scheme, thereby allowing users to check the correctness of the search results and achieving the fine-grained access control. Besides, our scheme considers the access privileges of the same data according to attribute-based priority tree. The formal security analysis proves that our scheme is secure against the chosen-keyword attacks in the generic bilinear group model, and the experimental simulations using a real-world dataset demonstrate its efficiency and feasibility in practice.

V2X security: A case study of anonymous authentication

Vehicle to Everything (V2X) is the enabling technique for future connected cars. Security is essential to the V2X technology, and privacy is an integral element of V2X security. It has been recognized that privacy preserving/anonymous authentication is a fundamental step towards achieving privacy protection in V2X. We are thus motivated to study anonymous authentication, as a case study of V2X security. Specifically we propose two lightweight anonymous credential schemes for anonymous authentication in V2X: one is under the rationale of “witness update outsourcing”, and is applicable to V2V; the other is suitable for V2I, with the characteristic that a vehicular OBU is enabled to operate entirely on the compact bilinear group. We conduct performance analysis both analytically and empirically, and get promising results.

Accumulable optimistic fair exchange from verifiably encrypted homomorphic signatures

Let us consider a situation where a client (Alice) frequently buys a certain kind of product from a shop (Bob) (e.g., an online music service sells individual songs at the same price, and a client buys songs multiple times in a month). In this situation, Alice and Bob would like to aggregate the total transactions and pay once per month because individual payments are troublesome. Though optimistic fair exchange (OFE) has been considered in order to swap electronic items simultaneously, known OFE protocols cannot provide such aggregate function efficiently because various costs are bounded by the number of transactions in the period. In order to run this aggregation procedure efficiently, we introduce a new kind of OFE called accumulable OFE (AOFE) that allows clients to efficiently accumulate payments in each period. In AOFE, any memory costs, computational costs, and communication complexity of the payment round must be constant in terms of the number of transactions. Since a client usually has just a low power and poor memory device, these efficiencies are desirable in practice. Currently, known approaches (e.g., based on verifiably encrypted signature scheme) are not very successful for constructing AOFE. Thus, we consider a new approach based on a new cryptographic primitive called verifiably encrypted homomorphic signature scheme (VEHS). In this paper, we propose a generic construction of AOFE from VEHS and also present a concrete VEHS scheme over a composite-order bilinear group by using the dual-form signature techniques. This VEHS scheme is also of independent interest. Since we can prove the security of VEHS without random oracles, our AOFE protocol is also secure without random oracles. Finally, we implemented our AOFE protocol, and it is efficient enough for practical use.

Towards secure and flexible EHR sharing in mobile health cloud under static assumptions

Electronic health record (EHR) systems are promising in the management of individual’s health. However, before widely deployed in practical applications, EHR systems have to tackle the privacy and efficiency challenges. Most of existing EHR sharing schemes suffer from severe efficiency drawbacks, resulting in inapplicability in mobile EHR system. Furthermore, the security assumptions in the previous schemes are usually based on non-static assumptions. In this paper, we propose a flexible EHR sharing scheme supporting offline encryption of EHR and outsourced decryption of EHR ciphertexts in mobile cloud computing. The proposed scheme is proven secure in the random oracle model under the static decisional bilinear Diffie–Hellman assumption. In our EHR sharing system, an EHR owner only need one multiplication in bilinear groups to generate the final EHR ciphertexts based on the offline ciphertexts computation, and an EHR user can easily decrypt the EHR cipheretext without requiring bilinear pairing operations based on the transformed ciphertexts from the EHR cloud. Our EHR sharing scheme allows access structures encoded in linear secret sharing schemes. Performance comparisons indicate that our scheme is very suitable for mobile health clouds.

A Non-interactive Deniable Authentication Scheme in the Standard Model

Deniable authentication protocols enable a sender to authenticate a message to a receiver such that the receiver is unable to prove the identity of the sender to a third party. In contrast to interactive schemes, non-interactive deniable authentication schemes improve communication efficiency. Currently, several non-interactive deniable authentication schemes have been proposed with provable security in the random oracle model. In this paper, we study the problem of constructing non-interactive deniable authentication scheme secure in the standard model without bilinear groups. An efficient non-interactive deniable authentication scheme is presented by combining the Diffie-Hellman key exchange protocol with authenticated encryption schemes. We prove the security of our scheme by sequences of games and show that the computational cost of our construction can be dramatically reduced by applying pre-computation technique.

A privacy-aware data dissemination scheme for smart grid with abnormal data traceability

In a typical smart grid, a large number of smart meters are deployed at energy consumers’ premises, which can report real-time usage data to the control center of the energy producer. Although such a communication model can help to improve the efficiency and reliability of electricity delivery, which is crucial to our society, it also leads to several security issues: (1) attackers may violate the privacy of energy consumers, and (2) attackers may tamper with the transmitted data for their own benefits or purposes. To deal with these security issues, many researchers have proposed different schemes for privacy preservation or abnormal data detection. However, existing studies usually address them separately. In this paper, we jointly resolve these two major security issues in the smart grid. Specifically, we propose a privacy-aware data dissemination scheme for smart grid with abnormal data traceability (PDDS), based on bilinear group theory and non-interactive zero-knowledge proof. In our scheme, we design a novel link function that can verify whether there are different signatures that are signed by the same consumer, which effectively reduces the time and communication overhead for tracing. To evaluate the correctness and performance of the proposed scheme, we first develop a solid security analysis, which shows that the proposed scheme can efficiently preserve identity confidentiality and data integrity. We then conduct extensive simulation experiments, which further demonstrate that our scheme can significantly reduce communication costs.

Efficient revocable identity-based encryption via subset difference methods

Providing an efficient revocation mechanism for identity-based encryption (IBE) is very important since a user's credential (or private key) can be expired or revealed. revocable IBE (RIBE) is an extension of IBE that provides an efficient revocation mechanism. Previous RIBE schemes essentially use the complete subtree (CS) scheme of Naor, Naor and Lotspiech (CRYPTO 2001) for key revocation. In this paper, we present a new technique for RIBE that uses the efficient subset difference (SD) scheme of Naor et al. instead of using the CS scheme to improve the size of update keys. Following our new technique, we first propose an efficient RIBE scheme in prime-order bilinear groups by combining the IBE scheme of Boneh and Boyen and the SD scheme and prove its selective security under the standard assumption. Our RIBE scheme is the first RIBE scheme in bilinear groups that has O(r) number of group elements in an update key where r is the number of revoked users. Next, we also propose another RIBE scheme in composite-order bilinear groups and prove its full security under static assumptions. Our RIBE schemes also can be integrated with the layered subset difference scheme of Halevy and Shamir (CRYPTO 2002) to reduce the size of a private key.

Shorter Quasi-Adaptive NIZK Proofs for Linear Subspaces

We define a novel notion of quasi-adaptive non-interactive zero-knowledge (NIZK) proofs for probability distributions on parameterized languages. It is quasi-adaptive in the sense that the common reference string (CRS) generator can generate the CRS depending on the language parameters. However, the simulation is required to be uniform, i.e., a single efficient simulator should work for the whole class of parameterized languages. For distributions on languages that are linear subspaces of vector spaces over bilinear groups, we give computationally sound quasi-adaptive NIZKs that are shorter and more efficient than Groth–Sahai NIZKs. For many cryptographic applications quasi-adaptive NIZKs suffice and our constructions can lead to significant efficiency improvements in the standard model. Our construction can be based on any k-linear assumption, and in particular under the eXternal Diffie Hellman (XDH) assumption our proofs are even competitive with Random Oracle-based $$\Sigma $$ -protocol NIZK proofs. We also show that our system can be extended to include integer tags in the defining linear equations, where the tags are provided adaptively by the adversary. This leads to applicability of our system to many applications that use tags, e.g., applications using Cramer–Shoup projective hash proofs. Our techniques also lead to the shortest known (ciphertext) fully secure identity-based encryption scheme under standard static assumptions. Further, we also get a short publicly verifiable CCA2-secure IBE scheme.

Leakage‐resilient ID‐based signature scheme in the generic bilinear group model

AbstractSecurity mechanisms in the traditional cryptography have been modeled under the assumption that secret values (keys) are completely hidden to an adversary. Indeed, a number of side‐channel attacks (e.g., timing, power, fault, etc.) have been demonstrated to obtain partial information about secret keys. Leakage‐resilient cryptography is a countermeasure to withstand side‐channel attacks. Recently, a large number of leakage‐resilient cryptographic schemes or protocols have been proposed to resist various side‐channel attacks. Up to now, no work has been done on leakage‐resilient identity‐based signature (LR‐IBS). In this article, we propose the first LR‐IBS scheme based on Galindo and Vivek's leakage‐resilient signature. In the generic bilinear group model, we formally prove that our LR‐IBS scheme possesses existential unforgeability against identity and adaptive chosen message attacks under the continual leakage model. Copyright © 2016 John Wiley & Sons, Ltd.