Aggregate Signature Research Articles

Cloud based security on outsourcing using blockchain in E-health systems

Recently, Electronic Health Records (EHR) plays a significant role in E-health care system that allows data exchange of patient's health records via a portal designated by healthcare professionals. In this, the lack of confidentiality and integrity factors leads to different security issues on sensitive health information and causes a serious impact on a patient's life. To accomplish the security of medical data, we propose a new scheme named Elliptical Curve Certificateless Aggregate Cryptography Signature scheme (EC-ACS) for the public verification and auditing in the Medical Cloud Server (MCS) to secure EHR using authorized blockchain technology. In this, we use Elliptic Curve Cryptography (ECC) to encrypt medical data and the Certificateless Aggregate Signature scheme (CAS) to generate the digital signature for sharing and storing data in the cloud storage. This proposed scheme ensures security, privacy and safeguards the confidential information from unauthorized access in the cloud health system. Furthermore, the blockchain technique guarantees the integrity, traceability and secure storage of medical records in the cloud environment.

Improved Security of a Pairing-Free Certificateless Aggregate Signature in Healthcare Wireless Medical Sensor Networks

Certificateless aggregate signature (CLAS) schemes reduce the trust on the key generation center of identity-based signatures and thus partially address the inherent key escrow issue in identity-based cryptosystems while retaining the advantage of implementation efficiency. In the past few years, a number of new CLAS schemes were proposed to overcome the communicational and computational limitations of sensors and attain integrality, validity, and availability of patients’ medical data in healthcare wireless medical sensor networks (HWMSNs). However, many of these schemes do not provide enough security guarantees. In this article, we first review a most recent CLAS scheme for HWMSNs and show that it is insecure for medical applications by presenting attacks due to a type I adversary and a type II adversary. Then, we put forth an improved construction which is provably secure under the CLAS security model in the random oracle model. Our detailed analyses demonstrate that the proposed scheme not only overcomes the security flaws but also has higher implementation efficiency and lower communication cost.

Fully invisible protean signatures schemes

Protean signatures (PSs), recently introduced by Krenn et al. (CANS ‘18), allow a semi-trusted third party (the sanitiser), to modify a signed message in a controlled way: the signer can define the message parts to be arbitrarily editable by the sanitiser, as well as message parts which can be redacted (but not altered otherwise) by the sanitiser. Thus, PSs generalise both redactable signatures (RSs) and sanitisable signatures (SSs) into a single notion. Invisibility for PSs guarantees that no outsider (i.e. any party not being signer or sanitiser) can decide which message parts can be edited. However, the current definition of invisibility does not prohibit that an outsider can decide which parts are redactable – only which parts can be edited are hidden. This negatively impacts the privacy guarantees provided by this definition. The authors extend PSs to be fully invisible. Their notion guarantees that an outsider can identify neither editable nor redactable parts. They, therefore, introduce the new notions of invisible RSs and invisible non-accountable SSs ( S S ′ ), along with a consolidated framework for aggregate signatures. Using those building blocks, their resulting construction is significantly more efficient than the original scheme by Krenn et al., which they demonstrate in a prototypical implementation.

Tesia: A trusted efficient service evaluation model in Internet of things based on improved aggregation signature

SummaryService evaluation model is an essential ingredient in service‐oriented Internet of things (IoT) architecture. Generally, traditional models allow each user to submit their comments with respect to IoT services individually. However, these kind of models are fragile to resist various attacks, like comment denial attacks, and Sybil attacks, which may decrease the comments submission rate. In this article, we propose a new aggregation digital signature scheme to resolve the problem of comments aggregation, which may aggregate different comments into one with high efficiency and security level. Based on the new aggregation digital signature scheme, we further put forward a new service evaluation model named Tesia allowing specific users to submit the comments as a group in IoT networks. More specifically, they aggregate comments and assign one user as a submitter to submit these comments. In addition, we introduce the synchronization token mechanism into the new service evaluation model, to assure that all users in the group may sign their comments one by one, and the last one who receives the token is assigned as the final submitter. Tesia has more acceptable robustness and can greatly improve the comments submission rate with rather lower submission delay time.

An Efficient Certificateless Aggregate Signature Scheme for Blockchain-Based Medical Cyber Physical Systems.

Different from the traditional healthcare field, Medical Cyber Physical Systems (MCPS) rely more on wireless wearable devices and medical applications to provide better medical services. The secure storage and sharing of medical data are facing great challenges. Blockchain technology with decentralization, security, credibility and tamper-proof is an effective way to solve this problem. However, capacity limitation is one of the main reasons affecting the improvement of blockchain performance. Certificateless aggregation signature schemes can greatly tackle the difficulty of blockchain expansion. In this paper, we describe a two-layer system model in which medical records are stored off-blockchain and shared on-blockchain. Furthermore, a multi-trapdoor hash function is proposed. Based on the proposed multi-trapdoor hash function, we present a certificateless aggregate signature scheme for blockchain-based MCPS. The purpose is to realize the authentication of related medical staffs, medical equipment, and medical apps, ensure the integrity of medical records, and support the secure storage and sharing of medical information. The proposed scheme is highly computationally efficient because it does not use bilinear maps and exponential operations. Many certificateless aggregate signature schemes without bilinear maps in Internet of things (IoT) have been proposed in recent years, but they are not applied to the medical field, and they do not consider the security requirements of medical data. The proposed scheme in this paper has high computing and storage efficiency, while meeting the security requirements in MCPS.

Efficient Certificateless Aggregate Signature With Conditional Privacy Preservation in IoV

As an extension of traditional vehicular ad hoc networks, the Internet of Vehicles (IoV) enables information collection and dissemination, which brings a lot of convenience and benefits to the intelligent transportation systems. However, the booming IoV confronts a few challenges in the aspects of vehicle location privacy preservation and the authenticity of the transmitted information. In order to meet these challenges, we propose an efficient certificateless aggregate signature scheme with conditional privacy preservation in this article. Our scheme utilizes the technique of full aggregation to reduce the bandwidth resources and computing overhead. Besides, the conditional privacy preservation in IoV system is realized by using pseudonym mechanism. We demonstrate that the proposed scheme is secure against the Type-I and Type-II adversaries in the random oracle under the computational Diffie–Hellman assumption. In addition, the proposed scheme is compared with related works from aspects of computation cost, communication efficiency, and security requirements. The comparison results show that the proposed scheme is efficient, and it is suitable for resource-constrained environments.

A Security-Enhanced Certificateless Aggregate Signature Authentication Protocol for InVANETs

The pervasive communications between vehicles and dynamic mobility may significantly increase data exchange and therefore bring a huge amount of traffic data in InVANETs. Due to some environmental factors, like the vulnerability of wireless connection, limitation of in-car computing ability, and speed of vehicles, it is extremely challenging to design identity authentication protocols satisfying the requirements of both high security and efficiency simultaneously. To this end, the aggregate signature technology has been employed in InVANETs. However, the technology still suffers from high computational overhead due to the management of certificates, as well as the key escrow problem (i.e., the dependence on a fully trusted third party). In this article, we propose the SE-CLASA protocol for InVANETs in order to tackle the aforementioned problems. In addition, a novel factor-contained aggregation mechanism is proposed to resist an information injection attack investigated in our analysis. Moreover, we prove the security of the proposed SE-CLASA and conclude that it meets most known security requirements in a general InVANET scenario. Simulation results show the superiority of the proposed SE-CLASA, in terms of security and efficiency, compared to the most recent authentications in InVANETs.

A Lightweight Certificateless Aggregation Signature Scheme With Provably Security in the Standard Model

In an aggregate signature scheme, $n$ signatures on $n$ different messages from $n$ users can be combined into a single signature. By verifying the signature, the verifier believes that $n$ users did generate the $n$ corresponding signatures. In the recent decade, numerous certificateless aggregate signature (CLAS) schemes have been introduced. There are two issues with these schemes. First, it was in the random oracles model (ROM) that the security proofs of these schemes were given. ROM is an idealized model. A signature scheme is not necessarily secure in real life even if it has proven to be safe in ROM. Second, the number of hash-to-point operations increases linearly with the number of signers in these schemes, so that are not suited for the computation-constrained devices (such as mobile devices). In this article, a new certificateless signature scheme is constructed. Based on it, a new CLAS scheme is proposed. Under the hypothesis that it is hard to solve a computation Diffie–Hellman problem, two schemes are proved to be secure in the standard model. The CLAS scheme needs only three pairing operations and does not need a hash-to-point operation, taken into account the computation cost, it is more efficient than previous CLAS schemes.

Efficient Certificateless Aggregate Signature Scheme for Performing Secure Routing in VANETs

Certificateless public key cryptosystem solves both the complex certificate management problem in the public key cryptosystem based on the PKI and the key escrow issue in the public key cryptosystem based on identity. The aggregator can compress n different signatures with respect to n messages from n signers into an aggregate signature, which can help communication equipments to save a lot of bandwidth and computing resources. Therefore, the certificateless aggregate signature (CLAS) scheme is particularly well suited to address secure routing authentication issues in resource-constrained vehicular ad hoc networks. Unfortunately, most of the existing CLAS schemes have problems with security vulnerabilities or high computation and communication overheads. To avoid the above issues and better solve the secure routing authentication problem in vehicular ad hoc networks, we present a new CLAS scheme and give the formal security proof of our scheme under the CDH assumption in the random oracle model. We then evaluate the performance of our proposed CLAS scheme, and the results demonstrate that our proposal is more practical in resource-constrained vehicular ad hoc networks.

Forgery attacks on two provably secure certificateless signature schemes

Recently, Hashimoto and Ogata proposed a constant-size certificateless aggregate signature scheme based on bilinear pairings. Karati et al. constructed a new certificateless signature scheme without bilinear pairings. The schemes were proven secure against both Type I and Type II adversaries in the random oracle model under the hardness assumptions of the Elliptic Curve discrete logarithm problem and the Computational Diffie–Hellman problem. In this paper, we first show that Hashimoto and Ogata is insecure against a Super-Type I adversary who knows the user secret key associated to the replaced public key and suggest its improvement to prevent our attack. We also show that Karati et al.’s scheme is entirely broken: anyone can forge certificateless signatures on any messages for any identities from only publicly known information without using any secret information. Thus, the scheme is trivially insecure against the Type I adversary who can replace user public keys and the Type II adversary who knows the master secret key. The attack shows that their security proofs against the Type I and Type II adversaries are flawed since these forgery attacks are never reflected in the proofs. Thus, it should be proposed security models that cover various forgery attacks due to algebraic relations in the underlying groups.

On the security of privacy‐preserving authentication scheme with full aggregation in vehicular ad hoc network

AbstractCertificateless aggregate signature (CLAS) scheme is a very important cryptographic technique used in many internet of things (IoT) applications like healthcare wireless sensor networks, industrial IoT, smart agriculture, and smart transportation to achieve privacy and integrity of transmitted information, and improved efficiency. Recently, a privacy‐preserving authentication scheme based on CLAS scheme for secure communication in vehicular ad hoc network (VANET) which can achieve complete aggregation was proposed. The authors demonstrated that their scheme is semantically secure in the random oracle model based on the intractability of the computational Diffie‐Hellman (CDH) problem under the consideration of type I and II attacks. However, by giving two concrete attacks, we show that the scheme is insecure in the standard security model. Consequently, we propose a fix by modifying the sign, verify, and aggregate‐verify algorithms of the scheme. Afterwards, we demonstrate that with this modification, the improved scheme is semantically secure against forgery attacks in the random oracle model under the intractability of the CDH problem. An analysis of the performance of the proposed scheme and the related schemes shows the former is much more efficient and suitable for practical application.

Aggregatable Certificateless Designated Verifier Signature

In recent years, the Internet of Things (IoT) devices have become increasingly deployed in many industries and generated a large amount of data that needs to be processed in a timely and efficient manner. Using aggregate signatures, it provides a secure and efficient way to handle large numbers of digital signatures with the same message. Recently, the privacy issue has been concerned about the topic of data sharing on the cloud. To provide the integrity, authenticity, authority, and privacy on the data sharing in the cloud storage, the notion of an aggregatable certificateless designated verifier signature scheme (ACLDVS) was proposed. ACLDVS also is a perfect tool to enable efficient privacy-preserving authentication systems for IoT and or the vehicular ad hoc networks (VANET). Our concrete scheme was proved to be secured underling of the Computational Diffie-Hellman assumption. Compared to other related schemes, our scheme is efficient, and the signature size is considerably short.

Cryptanalysis of Two Signature Schemes for IoT-Based Mobile Payments and Healthcare Wireless Medical Sensor Networks

Certificateless cryptography does not require any certificate for the public key authentication and users' public keys are transmitted with ciphertext/signatures or by making them available in the IoT-based public directory in a proper way. Due to these features, certificateless cryptosystems are considered as fundamental cryptographic buildingblocks to provide authenticity, integrity and non-repudiation suitable for IoT applications. Yeh proposed a transaction scheme based on a certificateless signature scheme for IoT-based mobile payments implementing on Android Pay. He showed that the CLS scheme was unforgeable against Type I and Type II adversaries under the intractability of the mathematical problem. Despite the security proofs, we show that Yeh's scheme is still insecure against both Type I and Type II adversaries. Recently, Gayathri et al. constructed a compact certificateless aggregate signature scheme for Healthcare Wireless Medical Sensor Networks. Their aggregate signatures are constant-size independent of the number of signers. In this paper, we show that anyone can forge certificateless aggregate signatures of their scheme on any sets of messages and identities from only publicly known information, i.e. their scheme is entirely broken. We then discuss some improvements.

Security Vulnerabilities of Four Signature Schemes From NTRU Lattices and Pairings

Certificateless cryptography solves the certificate management problem in public-key cryptography and the key-escrow problem in identity-based cryptography. Xie et al. proposed a certificateless signature scheme using NTRU lattices. They proved that their scheme was existential unforgeable for Type I and Type II adversaries under the intractability of the Small Integer Solution (SIS) problem on NTRU lattices in the random oracle model. Subsequently, Hung et al. proposed a revocable certificateless signature scheme on NTRU lattices that gave a revocation method via public channels to revoke illegal or compromised users. They also proved that their scheme was existential unforgeable for Type I, Type II and Type III adversaries under the intractability of the SIS problem. Recently, Wang et al. proposed a certificateless aggregate signature scheme from bilinear pairings and Rezaeibagha et al. proposed a new lightweight certificateless scheme for Industrial Internet of Things from bilinear pairings. The security of their schemes was proven for Type I and Type II adversaries under the intractability of some mathematical problems. In this paper, we show that the two schemes on NTRU lattices are insecure against Type I or Type II adversaries. We also point out invalidity of Wang et al. ’s scheme and vulnerability of Rezaeibagha et al. ’s scheme against Type I attacks. We then suggest some improvements to prevent our attacks.

HOMOMORPHIC AGGREGATE SIGNATURE SCHEME WITH OUTSOURCING ALGORITHM BASED PRIVACY PRESERVING IN VANETS

One of the important paradigms of recent technological development has known to be Vehicular Ad-hoc Networks (VANETs) due to its current intelligent transportation network. Moreover, leakage of communication information or sensitive data in VANETs can leads to vulnerable attacks that may affect many properties and lives. For this reason, VANET systems need to have high-level security aspects. In addition, devices with less computing resources expected for fast computation power. Several researchers have analysed various privacy preserving models for VANETs to protect from different attacks, which is not enough to prevent from new attackers. In this research, a Homomorphic Aggregate Signature (HAS) scheme proposed for achieving unforgeable message attacks without having random oracle and new outsourcing algorithm is designed efficiently for exponential operations to reduce the computational cost in which matrices conjugate operation based on homomorphic mapping is used for achieving the security of both base and exponent numbers. In addition, a protocol based on privacy preserving is constructed for VANETs by using the proposed HAS scheme and outsourcing computing, in which the authentication is processed by presenting a proxy re-signature scheme. In this proposed protocol, RSU will act as an agent when TA authorizes it and OBU’s signatures are converted to TA’s signature by using RSU. Real-identity of OBU is traced by TA using its secret key when an unknown/malicious message is detected then the proposed protocol will provide traceability, privacy, and anonymity. Furthermore, pairing and exponential operations are not needed by the proposed scheme as ` complexity of calculations is reduced significantly for VANET system.

Secure Communication With Data Analysis and Auditing Using Bilinear Key Aggregate Cryptosystem in Cloud Computing

In the current technological world the cloud computing becomes very popular, where anyone can use the internet, and the remote servers to give retrieve data as well as applications. The users can use such applications via the cloud communications without any installation. That is using some web services any computer can access and maintains data of end-users. Even though the cloud computing environments provide lot of benefits in data and application accessing, there are many questions still coming up on how to gain a trusted environment for securing data and applications in clouds from hackers and intruders. Cloud storage should be able to store and share data securely, efficiently, and flexibly with others in cloud storage. Based on the number of decryption keys to be shared the cost also increased. In public key encryption both the keys (encryption key and decryption key) are different. This paper proposes a new era of bilinear key aggregate cryptography. To produce constant length cipher text is also one of important task that we have materialized. In this paper, we propose a simple, efficient, and publicly verifiable approach in cloud computing which provide security to data during data transfer between different users. Here we introduce Bilinear key aggregate cryptosystem. In the Proposed Approach, by utilizing public key based homomorphic authenticator with random masking privacy preserving Algorithm for secure data transmission. The new method bilinear aggregate signature can be used to achieve key auditing. Key auditing avoids the computation complexity

A unified framework of identity-based sequential aggregate signatures from 2-level HIBE schemes

Identity-based sequential aggregate signature (IBSAS for short) schemes, introduced by Boldyreva et al. [CCS 2007], allow a large quantity of signers to generate one signature sequentially, in which these messages as well as their order can be attested by employing their identities. In such a scheme, storage space and bandwidth overhead can be reduced. To our best knowledge, though many concrete IBSAS schemes have been constructed in literature, none of them is constructed under a standard computational hardness assumption and unforgeable under the standard model. The problem of how to construct such schemes is still open. Latterly, Gentry et al. [PKC 2018] proposed a unified construction of SAS (i.e., abbreviated form of sequential aggregate signature) schemes by employing trapdoor permutation and ideal ciphers. Motivated by the above problem and hints, here we study how to construct IBSAS schemes in a new unified perspective. By employing 2-level HIBE (i.e., abbreviated form of hierarchical identity-based encryption) schemes, we present unified construction of IBSAS schemes and give a rigorous proof of their unforgeability. The unified construction is then instantiated to get a concrete IBSAS scheme, which has existential unforgeability under the standard model using a standard computational hardness assumption (i.e., the CDH assumption). An extra fruit is that it can be used to construct an existentially unforgeable IBSAS scheme using the Learning with Errors problem, which is constructed under a lattice hardness assumption for the first time. In the end, we show a detailed performance comparison among our schemes and previous ones.

A Group Signature and Authentication Scheme for Blockchain-Based Mobile-Edge Computing

Blockchain-based mobile-edge computing (BMEC) is an innovative architecture, which is essential in the future fifth-generation (5G) network era. BMEC solves the problem of limited computing resources of devices in the mobile blockchain environment while ensuring the distributed deployment of computing resources and the traceable of transaction data. However, the blockchain technology has many security vulnerabilities, among which attacks against consensus algorithms are particularly serious, i.e., double-spend attacks, long-range attacks, and selfish mining. All of these attacks can break the integrity of BMEC, allowing the correct block record to be overwritten with a false one. In this article, we propose a group signature scheme designed for validating blocks of blockchain to address such issues. Each new block will be regarded as a valid block if it obtains a valid group aggregate signature of the group which the block creator belongs to. We describe in detail the process of authentication and key changes when mobile devices join and leave BMEC. We also provide a more efficient authentication scheme of authenticating mobile devices compared to traditional schemes in BMEC. Last, the security analysis is presented to prove that our proposed group signature scheme is effective.

Certificateless aggregate signature scheme secure against fully chosen-key attacks

Certificateless aggregate signature (CLAS) schemes enjoy the benefits of both certificateless cryptography and aggregate signature features. Specifically, it not only simplifies the certificate management without introducing the key escrow problem but also transforms many signatures into one aggregate signature to save communication and computation cost.CLAS is a powerful cryptographic tool, yet its security should be thoroughly analyzed before being implemented. In this paper, we give a new insight into the security of CLAS schemes. We introduce a potential and realistic attack called fully chosen-key attacks that has not been considered in the traditional security models and define the security model against fully chosen-key attacks. In contrast to the traditional models, the adversary is allowed to hold all the signers’ private keys and its goal is not to forge an aggregate signature but to output invalid single signatures that can be aggregated into a valid aggregate signature. We find there is no CLAS scheme secure in traditional security models that is secure against fully chosen-key attacks and then demonstrate how to reinforce the security of an existing scheme to withstand such an attack.

Secure and efficient certificateless aggregate signature scheme from bilinear pairings

ABSTRACTThe most important contribution of modern cryptography is the invention of digital signatures. To deal with specific application scenarios, digital signature schemes have been evolved with different variants. One of such variants is the aggregate signature scheme, which allows aggregation of different signatures by different users on different messages, to achieve computational and communication efficiency. Such schemes are useful in the design of Wireless Sensor Networks, Mobile Ad-hoc Networks, and Vehicular Ad-hoc Networks, where storage, bandwidth, and computational complexity are major constraints. In order to improve the computational and communicational efficiency along with security, in this paper, we propose a novel Certificateless Aggregate Signature (CLAS) scheme and extended it to achieve full aggregation. The proposed CLAS scheme uses bilinear pairings over elliptic curves and is proven secure in the Random Oracle Model under the assumption that Computational Diffie–Hellman Problem is hard. The security of the proposed CLAS scheme is proven without using forking lemma to achieve tight security. We compared our scheme with well-known existing schemes. Efficiency analysis shows that our scheme is much efficient than existing schemes in terms of communication and computational costs.