Identity-based Cryptosystem Research Articles

BSLA: Blockchain-assisted Secure and Lightweight Authentication for SGIN

Space–Ground Integrated Network (SGIN) can dramatically reduce the coverage restriction of terrestrial networks, and it therefore can meet the high service requirements to achieve low-latency and high-speed global interconnection at anytime and anywhere. Due to the vulnerable communication channels and the limited resources of spatial nodes such as satellite, SGIN is facing many potential threats. As the first gateway of the SGIN, access authentication is an essential step that guarantees the internal security of the network. However, there are some problems in traditional cryptosystem-based authentication mechanisms, such as certificate management problem and centralized key escrow problem. Consequently, designing a lightweight and secure identity authentication protocol can effectively solve the problems faced by SGIN. In this paper, we focus on the private key escrow problem caused by the Private Key Generator (PKG) in Identity-Based Cryptosystems (IBC) mechanism, and propose a Blockchain-assisted Secure and Lightweight Authentication (BSLA) scheme which introduces the blockchain to improve the robustness and reliability of authentication. In BSLA, user’s private key is determined by itself through combining the partial private keys from different PKGs, which prevents the risk of private key exposure caused by single PKG. Meanwhile, the blockchain also serves as the information source for synchronizing user revocation lists to the spatial nodes, which realizes the fast detection of user revocation. We further analyse the security of BSLA and the analytical results show that BSLA can meet various security requirements. In addition, according to the performance evaluation results, BSLA has good scalability in terms of key security strength. Therefore, users can choose different key security strength and make a trade-off between efficiency and security based on the specific requirements.

Data Access Control in Cloud Computing: Flexible and Receiver Extendable

Broadcast encryption provides a promising technique of data access control for specified users in cloud computing. A data uploader can generate a ciphertext for a set of chosen users such that only the intended users are able to access the data. However, with the rapidly increasing of collaboration between users, it is desired to extend the receiver set to grant decryption right for more users. The existing broadcast encryption systems cannot support receiver extension. In this article, we for the first time take this problem into consideration and give a solution. We take the merits of identity-based cryptosystem and propose a notion of EIBBE: a flexible data access control with receiver extendable for cloud computing based on broadcast encryption. It allows the authorized user to extend the receiver set <inline-formula><tex-math notation="LaTeX">$S$</tex-math></inline-formula> stated in the IBBE ciphertext by adding a new receiver set <inline-formula><tex-math notation="LaTeX">$S^{\prime }$</tex-math></inline-formula> without re-encryption. Both the users in <inline-formula><tex-math notation="LaTeX">$S$</tex-math></inline-formula> and <inline-formula><tex-math notation="LaTeX">$S^{\prime }$</tex-math></inline-formula> can access the data successfully. Moreover, the data uploader determines the maximum number of extended receivers. We then give a concrete construction of EIBBE and provide a rigorous security analysis of our proposed scheme. Finally, we demonstrate the scheme's efficiency and feasibility.

Heterogeneous Signcryption Scheme From IBC to PKI With Equality Test for WBANs

The signcryption protocols supporting the equality test are only for a single system rather than a flexible heterogeneous environment of wireless body area networks (WBANs). In this article, this problem is efficiently addressed through a proposed heterogeneous signcryption scheme from identity-based cryptosystem (IBC) to public key infrastructure (PKI) with an equality test (HSCIP-ET) for WBANs. Our scheme allows the sensors planted or worn by a user in the IBC system to signcrypt sensitive data using the public key of the management center in the PKI system, and then uploading it to the cloud server. Subsequently, the equality test can be executed by the cloud server on diverse ciphertexts to determine whether they contain the identical plaintext and return the corresponding result after receiving a request from an application provider. Furthermore, a rigorous analysis and an experimental comparison demonstrate the security and efficiency of the HSCIP-ET approach, respectively.

A key-escrow free identity-based signature scheme without requirement of a secure channel in the private key issuance phase

Identity-based cryptosystem (IBC) provides us the simplest key management procedures over traditional public key cryptosystem (PKC) as it eliminates the need for certificates of PKC. Hence, no certificate management activities are involved in IBC. However, there are two major drawbacks with the identity-based cryptosystem. One is the key-escrow problem and the other one is the necessity of a channel which is secure for the transmission of the private key, generated by a trusted centre called key generation centre (KGC). In this work, we propose an identity-based signature scheme, fitted in an existing established variant IBC model. The proposed scheme avoids the necessity of the secure channel as well as it is key-escrow free. The proposed scheme is constructed using bilinear pairings and based on the blinding-binding technique.

A Lightweight Nature Heterogeneous Generalized Signcryption (HGSC) Scheme for Named Data Networking-Enabled Internet of Things

Internet of Things (IoT) is the collection of different types of smart objects like mobile phones, sensors, cars, smart cities, smart buildings, and healthcare, which can provide a quality life to humans around the globe. These smart objects sense and produce a huge amount of data for distribution. The current hostcentric networking paradigm is not that scalable to provide a suitable solution to the idea of IoT. For scalable connectivity and efficient distribution, Named Data Networking (NDN) has been envisioned as a promising solution for future internet architecture. On the other hand, the significant issues regarding the adaptation of NDN with IoT possess security concerns such as authentication, confidentiality, integrity, and forward secrecy. As IoT is a heterogeneous environment, it demands a different type of security, according to the environmental situation such as public key infrastructure (PKI), identity-based cryptosystem (IBC), and certificateless cryptosystem (CLC). This paper presents a new concept of CLC to IBC heterogeneous generalized signcryption for the first time to fulfil the prime security requirements of NDN-based IoT. The proposed scheme provides the security properties according to situational needs without disturbing the structural policy of NDN. Considering the resource-constrained nature of IoT, we used a lightweight type of elliptic curve called the hyperelliptic curve cryptosystem which offers the same level of security as that of bilinear pairing and an elliptic curve cryptosystem using a minimum key size. Further, we compare the proposed scheme with recently proposed identity-based as well as certificateless generalized signcryption schemes, and the results give satisfactory outputs in terms of computational and communication resources. Furthermore, we simulate the proposed scheme with Automated Validation of Internet Security Protocols and Applications (AVISPA), and the results show that our scheme is valid and safe. Additionally, we provide a practical scenario of the proposed on NDN with an IoT-based smart city.

A Conditional Privacy Protection Scheme Based on Ring Signcryption for Vehicular Ad Hoc Networks

Vehicular ad hoc networks (VANETs) leverage information and communications technology to make transportation systems intelligent, safe, and efficient, hence improving people’s driving experience. Unfortunately, due to the openness of wireless channels and vehicular mobility, privacy leakage in VANETs poses serious privacy concerns. Once a user’s identity is leaked, it will cause serious threats to his/her property and personal safety as a malicious attacker, such as a stalker could utilize the targeted identity to track particular driver and/or launch malicious attack. To address such a privacy problem, by observing the nice properties of ring signature like anonymity, spontaneity, flexibility, and membership equality, we design a novel conditional privacy protection scheme based on ring signcryption, which utilizes the salient features of identity-based cryptosystems and ring signature to achieve conditional privacy. Through security analysis and experiments, we have demonstrated the advantage of our scheme over most existing solutions.

An Efficient Hybrid Signcryption Scheme With Conditional Privacy-Preservation for Heterogeneous Vehicular Communication in VANETs

Vehicular ad hoc networks (VANETs) ensure improvement in road safety and traffic management by allowing the vehicles and infrastructure that are connected to them to exchange safety messages. Due to the open wireless communication channels, security and privacy issues are a major concern in VANETs. A typical attack consists of a malicious third party intercepting, modifying and retransmitting messages. Heterogeneous vehicular communication in VANETs occurs when vehicles (only) or vehicles and other infrastructure communicate using different cryptographic techniques. To address the security and privacy issues in heterogeneous vehicular communication, some heterogeneous signcryption schemes have been proposed. These schemes simultaneously satisfy the confidentiality, authentication, integrity and non-repudiation security requirements. They however fail to properly address the efficiency with respect to the computational cost involved in unsigncrypting ciphertexts, which is often affected by the speeds at which vehicles travel in VANETs. In this paper, we propose an efficient conditional privacy-preserving hybrid signcryption (CPP-HSC) scheme that uses bilinear pairing to satisfy the security requirements of heterogeneous vehicular communication in a single logical step. Our scheme ensures the transmission of a message from a vehicle with a background of an identity-based cryptosystem (IBC) to a receiver with a background of a public-key infrastructure (PKI). Furthermore, it supports a batch unsigncryption method, which allows the receiver to speed up the process by processing multiple messages simultaneously. The security of our CPP-HSC scheme ensures the indistinguishability against adaptive chosen ciphertext attack (IND-CCA2) under the intractability assumption of q -bilinear Diffie-Hellman inversion ( q -BDHI) problem and the existential unforgeability against adaptive chosen message attack (EUF-CMA) under the intractability assumption of q -strong Diffie-Hellman ( q -SDH) problem in the random oracle model (ROM). The performance analysis indicates that our scheme has an improvement over the existing related schemes with respect to the computational cost without an increase in the communication cost.

Heterogeneous Signcryption With Equality Test for IIoT Environment

The existing signcryption schemes with equality testing are aimed at a sole cryptosystem and not suitable for the sophisticated heterogeneous network of Industrial Internet of Things (IIoT). To deal with this challenge, we propose a heterogeneous signcryption scheme with equality test (HSC-ET) in this article. This scheme enables a sensor in public key infrastructure (PKI) to execute data encryption and deliver it to the semitrusted entity (cloud server). When a user in an identity-based cryptosystem (IBC) intends to search for some data stored on the cloud server. The delegated cloud server executes tests on ciphertexts for determining whether the same underlying plaintext exists between two ciphertexts. These two ciphertexts can be one signcrypted ciphertext and one encrypted ciphertext, or both encrypted/signcrypted ciphertext, thus achieving a flexible search to the ciphertext. HSC-ET is demonstrated to be secure by the rigorous and detailed analysis. The experimental simulation and analysis results show the efficiency of our scheme.

Novel efficient identity-based signature on lattices

With the rapid development of electronic information technology, digital signature has become an indispensable part of our lives. Traditional public key certificate cryptosystems cannot overcome the limitations of certificate management. Identity-based cryptosystems can avoid the certificate management issues. The development of quantum computers has brought serious challenges to traditional cryptography. Post-quantum cryptography research is imperative. At present, almost all post-quantum identity-based signature (IBS) schemes are constructed using Gaussian sampling or trapdoor technologies. However, these two technologies have a great impact on computational efficiency. To overcome this problem, we construct an IBS scheme on lattices by employing Lyubashevsky’s signature scheme. Based on the shortest vector problem on lattices, our scheme does not use Gaussian sampling or trapdoor technologies. In the random oracle model, it is proved that our scheme is strongly unforgeable against adaptive chosen messages and identity attacks. The security level of our scheme is strongly unforgeable, which is a higher level than the existential unforgeability of other schemes. Compared with other efficient schemes, our scheme has advantages in computation complexity and security.

Escrow-Less Identity-Based Signature Scheme with Outsourced Protection in Cloud Computing

The identity-based cryptosystem (IBC) outfits with the most beneficial key management procedures. The IBC is bounded to the small network system due to the internal key escrow problem, which leads to two other problems: key abusing and user slandering problems. Some solutions that address the key escrow problem are certificate-less cryptosystems and multiple authorities-based IBC. However, they are expensive in terms of computation or loss of the identity-based feature. This paper presents an escrow-less identity-based signature (EL-IBS) scheme, where we employ one key generation center that authenticates a user and many authorities that issue a protected private key share without user authentication. We also outsource the key protection overhead to the cloud privacy centers. We proved that the our EL-IBS scheme is existential unforgeable, key abusing and existential user slandering secured against adaptively chosen message attack under the random oracle model and the well-known computational Diffie–Hellman problem.

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.

Adaptively secure certificate-based broadcast encryption and its application to cloud storage service

The existing public key broadcast encryption schemes are mainly constructed in identity-based cryptosystem, which bears the inherent problems of key escrow and key distribution. The certificate-based encryption mechanism can effectively address the problems in identity-based cryptosystem. Meanwhile, it simplifies the certificate revocation issue for traditional public key cryptosystem. Inspired by the idea of certificate-based encryption, we put forward the new primitive certificate-based broadcast encryption as well as its formal definition and security model. In virtue of prime order bilinear groups, we present an instantiation scheme of certificate-based broadcast encryption. To our best knowledge, the proposed scheme is the first adaptively secure scheme for certificate-based broadcast encryption in the standard model against chosen-ciphertext attack. Compared with the previous work, our scheme has advantages in the respects of computation cost as well as security properties. Furthermore, we present an application scenario of the proposed scheme for data access control in cloud storage service.

Anonymous Certificate-Based Broadcast Encryption With Personalized Messages

Broadcast encryption with personalized messages (BEPM) is a newly proposed cryptographic primitive, which supports a broadcaster to deliver the common encrypted broadcast message to a group of authorized users. It also supports a broadcaster to deliver the personalized messages to the individual authorized users simultaneously. However, none of the existing BEPM schemes consider the anonymity of authorized users, which is a crucial security requirement for many BEPM application scenarios. Besides, the previous studies on BEPM only achieve security against chosen-plaintext attack adversaries. Certificate-based cryptosystem gives a viable way to construct more secure and efficient BEPM schemes. We propose the new concept of anonymous certificate-based broadcast encryption with personalized messages (ANON-CBBE-PM). Subsequently, we illustrate the formal definition and the security model of ANON-CBBE-PM. Furthermore, we present an ANON-CBBE-PM scheme, which solves key escrow problem in identity-based cryptosystem and certificate management problem in traditional public key cryptosystem. Compared with the existing BEPM schemes, the proposed scheme not only protects the privacy of authorized users, but also has advantage in performance. To be more specific, the lengths of the user secret key and the system public parameters, as well as the cost for decryption are constant. For those BEPM applications with a multitude of users whose computing ability is limited, the proposed scheme is more practical. In addition, our scheme simultaneously achieves anonymity and confidentiality under adaptive chosen-ciphertext attack in the standard model.

Revocable identity-based encryption with server-aided ciphertext evolution

The utmost important problem in identity-based cryptosystems is the issue of user revocation. One of the existing solutions in the literature is to issue extra time keys periodically for every non-revoked user over public channels. Unfortunately, this solution is inefficient and very impractical when applying to the cloud. Because the scheme requires different time keys to allow data decryption for different time periods, and therefore the user has to keep a long list of time keys, which grows linearly with time. Furthermore, it is worth noting that ciphertexts produced prior to the revocation will remain available to the revoked users, which is undesirable for most application scenarios. To the best of our knowledge, there is no existing work that can solve both the aforementioned problems simultaneously in a practical manner. In this paper, we present an efficient solution called ciphertext evolution. The ciphertexts evolve to new ones with cloud's aid and the old ones are deleted. At any time, the data user has to utilize its current decryption key to decrypt ciphertexts in the cloud. So, all the past time keys become invalid and the user only needs to keep the current one. If the user is revoked, it cannot decrypt any ciphertext in the cloud because it does not have the current time key. We present generic and concrete constructions of revocable identity-based encryption with ciphertext evolution (RIBE-CE), which are proven based on the IND-CPA security model. Subsequently, we also extend RIBE-CE to the broadcast setting by giving generic and concrete constructions of revocable identity-based broadcast encryption with ciphertext evolution, which are secure under the IND-sID-CPA security model. Our schemes can be applied to the (group) data sharing, which is very practical and applicable to the cloud setting.

CCA-Secure and Revocable Certificateless Encryption with Ciphertext Evolution

Certificateless cryptosystems have attracted great interests in cryptographic research since its invention. Because compared with traditional public key cryptosystems or identity-based cryptosystems, they could not only simplify the certificate management, but also alleviate the key escrow problem. In certificateless cryptosystems, user revocation is a challenging issue. To address this issue, one popular method is to update the key via public channels. However, most of the existing schemes in this approach are impractical because of the following two shortcomings. Firstly, the user needs to maintain a list of decryption keys, but the size of the list will keep increasing. Secondly, the revoked user can still recover the plaintexts of the encrypted data prior to revocation, and this is a particular threat in some applications. To solve these problems, this paper presents revocable certificateless encryption with ciphertext evolution. We give a generic construction and then describe how it can be initialized concretely. In our proposed scheme, the user only needs to keep one decryption key, and once a user is revoked, it can no longer decrypt any ciphertext in the server. Moreover, the IND-CCA security model is defined against three types of attacks. And our schemes are formally proved to satisfy these security requirements.

Role-Based Access Control Model for Cloud Storage Using Identity-Based Cryptosystem

As the security of cloud storage cannot be effectively guaranteed, many users are reluctant to upload their key data to the cloud for storage, which seriously hinders the development of cloud storage. Since ensuring the confidentiality of user data and avoiding unauthorized access is the key to solving the security problems of cloud storage, there has been much cryptographic research proposing the use of the combination of cryptography technologies and access control model to guarantee the data security on untrusted cloud providers. However, the vast majority of existing access control schemes for ciphertext in cloud storage do not support the dynamic update of access control policies, and the computational overhead is also very large. This is contrary to the needs of most practical applications, which leverage dynamic data and need low computation cost. To solve this problem, combined with identity-based cryptosystem (IBC) and role-based access control (RBAC) model, we propose an RBAC (In this paper we use RBAC1 model which is richer access control model)) scheme for ciphertext in cloud storage. We also give the formal definitions of our scheme, a detailed description of four tuple used to represent access control strategy, the hybrid encryption strategy and write-time re-encryption strategy, which are designed for improving the system efficiency. The detailed construction processes of our scheme which. Include system initialization, add and delete users, add and delete permissions, add and delete roles, add and delete role inheritance, assign and remove user, assign and remove permission, read and write file algorithm are also given. Finally, we analyze the scheme and prove that it is correct, access control preserving (AC- preserving) and secure.

Multi-Keyword Certificateless Searchable Public Key Authenticated Encryption Scheme Based on Blockchain

As a quite attractive secure search mechanism in cloud environments, searchable encryption allows encrypted files to be searched by keyword and does not reveal any information about original data files. However, most existing searchable encryption schemes only support single keyword ciphertext retrieval, and they cannot resist against inside keyword guessing attacks. Besides, the previous schemes rarely focus on integrity verification and fair transactions without any third party. Focusing on these problems, we propose a multi-keyword certificateless searchable public key authenticated encryption scheme based on blockchain. We use certificateless cryptosystem to encrypt keywords, which avoids the problems of certificate management in traditional cryptosystem and key escrow in identity-based cryptosystem. Our scheme also supports multi-keyword search, which locates encrypted files precisely and returns the desired files. Moreover, we upload the real encrypted files to the cloud server, while the encrypted indexes are put in blockchain, which ensures the anti-tampering, integrity and traceability of the encrypted indexes. The anti-tampering of blockchain also ensures that users can receive accurate search results without any third party verification. Furthermore, we utilize smart contract to track monetary rewards, which enables fair transactions between data owners and users without any trusted third party. We prove that the proposed scheme is secure against inside keyword guessing attacks in the random oracle model. Finally, our performance evaluation shows that the proposed scheme has higher computational performance than other related schemes.

An Identity Based-Identification Scheme With Tight Security Against Active and Concurrent Adversaries

Identification schemes are used by machines to securely authenticate the identity of other machines or their users over computer networks. As conventional public key schemes require a trusted third party (TTP) or a public file to ensure the corresponding public key matches with the identity, identity-based cryptosystems emerged as a form of certificate-free system. The entity's identity is the public key itself, therefore eliminating the need for a TTP. The identity-based identification (IBI) scheme introduced by Kurosawa and Heng using their transform in 2004 remains as the only IBI derived from the Boneh-Lynn-Shacham (BLS) short signature scheme which has the advantage of shorter keys. We show tight security reduction against active and concurrent attackers (imp-aa/ca) on our scheme that is obtained from the same transform. As the transform will only produce schemes that are only secure against passive attackers (imp-pa), security against imp-aa/ca scheme relies on a strong One-More interactive assumption and therefore resulted in weak security. While the OR-proof method allows schemes secure against imp-pa to be secure against imp-aa/ca, the resulting security against imp-aa/ca will suffer from loose bounds in addition to the user secret keys being doubled in size. Our work avoids both OR-proof and strong interactive assumptions by showing an ad-hoc proof for our construction which utilizes the weaker well-studied co-computational Diffie-Hellman assumption and yet still has tight security against imp-aa/ca. We demonstrate the tight security of our scheme which allows usage of even shorter key sizes.

Redistributed Records Collections Personality Matching using Encrypted Cryptosystem

Sensitive information is gradually distributed in the cloud in this project's cloud computing and processing services to reduce costs, which raises concerns regarding data privacy. Encryption was a positive way to keep outsourced sensitive data secure, but it makes efficient use of data a very difficult process. In this paper, we focus on the issue of private matching in ide ntity-based cryptosystem over outsourced encrypted data sets that can simplify the management of certificates. To solve this proble m, we are proposing a private matching scheme based on identity

A preliminary study of bit-integer hash function for bilinear pairing identity-based cryptosystem

Hash function is a crucial part of identity-based cryptosystem, especially for identity-based cryptosystem that utilize bilinear pairing as its core mechanism. However, the hash function has specific requirement that most of commonly known function are not suitable for this purpose, especially the requirement that requires the output length of function is varies. A variable length hash function, such as HAVAL, only provide multiple option for its output length. While the identity-based cryptosystem require that the length of the output can be any number. This study aims to create a hash function to fulfil the identity-based cryptosystem requirement. This study modifies the MD5 hashing algorithm to produce a variable length output, which called the Bit-Integer hash function. The result shows a proof-of-concept that Merkle-Damgård construction can be used to create a variable length hash function. The hash value of Bit-Integer hash function can produce random-like result which is essential for any cryptographic hash function.