Identity-based Encryption System Research Articles

Retraction notice: IIBES: a proposed framework to improve the identity-based encryption system for securing federated learning

Retraction notice: IIBES: a proposed framework to improve the identity-based encryption system for securing federated learning

Research on Blockchain Transaction Privacy Protection Methods Based on Deep Learning

To address the challenge of balancing privacy protection with regulatory oversight in blockchain transactions, we propose a regulatable privacy protection scheme for blockchain transactions. Our scheme utilizes probabilistic public-key encryption to obscure the true identities of blockchain transaction participants. By integrating commitment schemes and zero-knowledge proof techniques with deep learning graph neural network technology, it provides privacy protection and regulatory analysis of blockchain transaction data. This approach not only prevents the leakage of sensitive transaction information, but also achieves regulatory capabilities at both macro and micro levels, ensuring the verification of the legality of transactions. By adopting an identity-based encryption system, regulatory bodies can conduct personalized supervision of blockchain transactions without storing users’ actual identities and key data, significantly reducing storage computation and key management burdens. Our scheme is independent of any particular consensus mechanism and can be applied to current blockchain technologies. Simulation experiments and complexity analysis demonstrate the practicality of the scheme.

Backward Compatible Identity-Based Encryption.

In this paper, we present a new identity-based encryption (IBE) system that is named Backward Compatible Identity-based Encryption (BC-IBE). Our BC-IBE is proposed to solve the problem caused by the out-of-synchronization between users' private keys and ciphertexts. Encryption systems such as revocable IBE or revocable Attribute-based Encryption (ABE) often require updating private keys to revoke users after a certain time period. However, in those schemes, an updated key can be used to decrypt the ciphertexts created only during the current time period. Once the key is updated and the previous keys are removed, the user, the owner of the updated key, will lose access to the past ciphertexts. In our paper, we propose BC-IBE that supports backward compatibility, to solve this problem. In our proposed system, user's private keys and ciphertexts can be updated periodically with time tags, and these processes can be used to revoke users who do not receive an updated key as the other revocable encryption does. However, in our proposed system, a private key newly issued to a user is backward compatible. This means that it decrypts not only the ciphertexts at the present time period but also all past ciphertexts. This implies that our proposed scheme guarantees the decryption of all encrypted data even if they are not synchronized. Compared to the existing revocable identity-based encryption system, our proposed BC-IBE has the advantage of simplifying key management and securely delegating ciphertext updates. Our proposed scheme only requires a single backward-compatible private key to decrypt all past ciphertexts created. Moreover, the ciphertext update process in our proposed scheme does not require any special privileges and does not require decryption. This means that this process can be securely delegated to a third-party server, such as a cloud server, and it prevents the potential leakage of secrets. For those reasons, BC-IBE is suitable for a system where users are more dynamic, such as the Internet-of-Things (IoT) network, or a system that regularly updates the data, like cloud data storage. In this paper, we provide the construction of BC-IBE and prove its formal security.

IIBES: a proposed framework to improve the identity-based encryption system for securing federated learning

Purpose In the field of cryptography, authentication, secrecy and identification can be accomplished by use of secret keys for any computer-based system. The need to acquire certificates endorsed through CA to substantiate users for the barter of encoded communications is one of the most significant constraints for the extensive recognition of PKC, as the technique takes too much time and susceptible to error. PKC’s certificate and key management operating costs are reduced with IBC. IBE is a crucial primeval in IBC. The thought behind presenting the IBE scheme was to diminish the complexity of certificate and key management, but it also gives rise to key escrow and key revocation problem, which provides access to unauthorised users for the encrypted information. Design/methodology/approach This paper aims to compare the result of IIBES with the existing system and to provide security analysis for the same and the proposed system can be used for the security in federated learning. Findings Furthermore, it can be implemented using other encryption/decryption algorithms like elliptic curve cryptography (ECC) to compare the execution efficiency. The proposed system can be used for the security in federated learning. Originality/value As a result, a novel enhanced IBE scheme: IIBES is suggested and implemented in JAVA programming language using RSA algorithm, which eradicates the key escrow problem through eliminating the need for a KGC and key revocation problem by sing sub-KGC (SKGC) and a shared secret with nonce. IIBES also provides authentication through IBS as well as it can be used for securing the data in federated learning.

A Provably Secure IBE Transformation Model for PKC Using Conformable Chebyshev Chaotic Maps under Human-Centered IoT Environments.

The place of public key cryptography (PKC) in guaranteeing the security of wireless networks under human-centered IoT environments cannot be overemphasized. PKC uses the idea of paired keys that are mathematically dependent but independent in practice. In PKC, each communicating party needs the public key and the authorized digital certificate of the other party to achieve encryption and decryption. In this circumstance, a directory is required to store the public keys of the participating parties. However, the design of such a directory can be cost-prohibitive and time-consuming. Recently, identity-based encryption (IBE) schemes have been introduced to address the vast limitations of PKC schemes. In a typical IBE system, a third-party server can distribute the public credentials to all parties involved in the system. Thus, the private key can be harvested from the arbitrary public key. As a result, the sender could use the public key of the receiver to encrypt the message, and the receiver could use the extracted private key to decrypt the message. In order to improve systems security, new IBE schemes are solely desired. However, the complexity and cost of designing an entirely new IBE technique remain. In order to address this problem, this paper presents a provably secure IBE transformation model for PKC using conformable Chebyshev chaotic maps under the human-centered IoT environment. In particular, we offer a robust and secure IBE transformation model and provide extensive performance analysis and security proofs of the model. Finally, we demonstrate the superiority of the proposed IBE transformation model over the existing IBE schemes. Overall, results indicate that the proposed scheme posed excellent security capabilities compared to the preliminary IBE-based schemes.

Cryptanalysis of Jain-Singh’s identity-based RSA encryption

ABSTRACT Identity-based Encryption (IBE) solves the problem of requiring key certificates in Public Key Encryption (PKE) by replacing the public key with the user’s identity. However, most IBE systems depend on Elliptic Curve Cryptography (ECC) which makes them time inefficient. Since Adi Shamir presented the idea of IBE, designing an IBE using an efficient encryption algorithm such as RSA still remains an open challenge. In 2017, Jain and Singh presented an identity-based variant of RSA. They claimed that their system is secure without any more computational overhead. In this paper, we analyze the security of Jain Singh’s identity-based RSA encryption. We launch two attacks against their system and prove that their system is not secure.

Server-aided Revocable IBE with Identity Reuse

Abstract Efficient key revocation in Identity-based Encryption (IBE) has been a both fundamental and critical problem when deploying an IBE system in practice. Boneh and Franklin proposed the first revocable IBE (RIBE) scheme where the size of key updates is linear in the number of users. Then, Boldyreva, Goyal and Kumar proposed the first scalable RIBE by using the tree-based approach where the size of key updates is $O(r\log (N/r))$ and the size of every user’s long-term secret key is $O(\log N)$ with $N$ being the number of users and $r$ the number of revoked users. Recently, Qin et al. presented the notion of server-aided RIBE where the size of every user’s long-term secret key is $O(1),$ and users do not need to communicate with Key Generator Center (KGC) during every key updates. However, users must change their identities once their secret keys are revoked as they cannot decrypt ciphertexts by using their revoked secret keys. To address the above problem, we formalize the notion of RIBE with identity reuse. In our system model, users can obtain a new secret key called the reuse secret key from KGC when their secret keys are revoked. The decryption key can be derived from the reuse secret key and new key updates while it cannot be derived from the revoked secret key and the new key updates. We present a concrete construction that is secure against adaptive-ID chosen plaintext attacks and decryption key exposure attacks under the $\mathsf{ADDH}1$ and $\mathsf{DDH}2$ assumptions in the standard model. Furthermore, we extend it to server-aided RIBE scheme with identity reuse property that is more suitable for lightweight devices.

Mobile access and flexible search over encrypted cloud data in heterogeneous systems

Never before has data sharing been more convenient with the rapid popularity and wide adoption of cloud computing. However, mobile access and flexible search with security for outsourced data in heterogeneous systems are two major obstacles prior to practical deployment of cloud computing. To meet the requirements in secure mobile access and flexible search to sensitive data, this paper, for the first time, proposes a versatile primitive referred to as an identity based proxy re-encryption system with outsourced equality test (IBPRE-ET). This primitive allows a data owner in an identity based broadcast encryption system (IBBE) seamlessly to share his/her data with a data sharer in an identity based encryption system (IBE). Moreover, it supports a data sharer in an IBBE system to perform search functionality on ciphertexts related to a data sharer in an IBE system. We also formally prove that the proposed IBPRE-ET system is selective secure using a random oracle model. Meanwhile, the theoretic evaluation and experimental result demonstrate our scheme is practical in the heterogeneous system. Finally, we show an application of our IBPRE-ET to the collaborative office automation system.

Revocable Broadcast Encryption with Constant Ciphertext and Private Key Size

In a revocable broadcast encryption scheme, the group manager can flexibly set revoked users who cannot decrypt the ciphertext. Many applications of the revocable broadcast encryption have been found in the secure cloud data sharing. An adaptively secure revocable broadcast encryption system with constant ciphertext and private key size under standard assumptions is more suitable for use in the cloud environment. Few existing revocable broadcast encryption schemes meet such a requirement. We propose a revocable broadcast encryption scheme with constant size ciphertext and private key by combining the RSA cryptographic accumulator with an efficient identity based encryption system. We prove it to be adaptively secure under standard assumptions using dual system encryption techniques.

Revocable hierarchical identity-based encryption via history-free approach

In the context of Identity-Based Encryption (IBE), both revocation and delegation of key generation are important functionalities. Although a number of IBE schemes with either efficient revocation or efficient delegation of key generation functionality have been proposed, an important open problem is efficiently delegating both the key generation and revocation functionalities in IBE systems. Seo and Emura (2014) [25] proposed the first realization of Revocable Hierarchical IBE (RHIBE), a sole IBE scheme that achieves both functionalities simultaneously. However, their approach implements history-preserving updates, wherein a low-level user must know the history of key updates performed by ancestors in the current time period, and it renders the scheme very complex.In this paper, we present a new method to construct RHIBE that implements history-free updates. Our history-free approach renders the scheme simple and efficient. As a second contribution, we redefine the security model for RHIBE to ensure security against insiders, where adversaries are allowed to obtain all internal system information, e.g., state information. In addition, we also consider the decryption key exposure attack, which was considered by Seo and Emura (2013) [23].Further, we propose two RHIBE schemes with shorter secret keys and constant size ciphertexts that implement the aforementioned history-free updates approach and security model. For revocation, our constructions use the Complete Subtree (CS) method and the Subset Difference (SD) method. Both schemes are selectively secure in the standard model under the q-weak Bilinear Diffie–Hellman Inversion assumption.

New chosen-ciphertext secure identity-based encryption with tight security reduction to the bilinear Diffie–Hellman problem

We propose a new identity-based encryption (IBE) system that achieves a tight security reduction to the bilinear Diffie–Hellman (BDH) problem in the random oracle model. Tightness indicates that some level of IBE system security can be straightforwardly based on the hardness of the BDH problem at the same security level. Achieving such tightness requires two strategies: (1) a key generation technique for all identities, and (2) a searching method for the solution to the BDH problem. To implement the first strategy, our system relies on a key generation paradigm recently introduced with the Park–Lee IBE system. To implement the second strategy, we base our system on the strong twin BDH problem that includes access to a decision oracle. We compare the efficiency of our system with that of the previous Nishioka IBE system (based on the Katz–Wang key generation paradigm) combined with another tight variant of the Fujisaki–Okamoto transform.

Anonymous hierarchical identity-based encryption without key delegation in decryption

Hierarchical identity-based encryption (HIBE) introduces the concept of hierarchical identity in identity-based encryption (IBE) which eases the burden of key generation centre. Anonymous identity-based encryption is another extension of IBE in which the ciphertext leaks no information about the target identity. In this paper, we propose a new anonymous hierarchical identity-based encryption system. Unlike previous anonymous HIBE system, our system needs no key delegation in decryption, i.e., the user can decrypt the ciphertext directly if his identity vector is the prefix of the target identity vector. So it is not necessary for the user to know the target identity vector, which enhances the practicality of anonymous HIBE systems. Our system is constructed in composite order groups and proven adaptive security and anonymity from four static assumptions by using the dual system encryption technique.

Information-theoretical secure verifiable secret sharing with vector space access structures over bilinear groups and its applications

As a basic tool, Verifiable Secret Sharing (VSS) has wide applications in distributed cryptosystems as well as secure multi-party computations. A number of VSS schemes for sharing a secret from a finite field, both on threshold access structures and on general access structures, have been available. In this paper, we investigate the verifiably sharing of a secret that is a random element from a bilinear group on vector space access structures. For this purpose, we present an information-theoretical secure VSS scheme, and then convert it to a modified one with improved efficiency. The performance and the security of the proposed schemes are analyzed in detail. Two examples are given to illustrate the applications of our proposed VSS schemes. One is the secure sharing of an organization’s private key in Boneh and Franklin’s identity-based encryption system, and the other is the distributed key generation and distributed decryption for bilinear ElGamal encryption system, both with vector space access structures.

Revocable hierarchical identity-based encryption

In practice, revocation functionality is indispensable to the public key cryptosystems since there are threats of leaking a secret key by hacking or legal situation of expiration of contract for using system. In the public key infrastructure setting, numerous solutions have been proposed, and in the Identity Based Encryption (IBE) setting, a recent series of papers proposed revocable IBE schemes. Delegation of key generation is also an important functionality in cryptography from a practical standpoint since it allows reduction of excessive workload for a single key generation authority. Although efficient solutions for either revocation or delegation of key generation in IBE systems have been proposed, an important open problem is efficiently delegating both the key generation and revocation functionalities in IBE systems. Even if the goal is very natural, there are some obstacles to achieve both functionalities at the same time. Libert and Vergnaud, for instance, left this as an open problem in their CT-RSA 2009 paper. In this paper, we propose the first efficient solution for this problem. We prove the selective-ID security of our proposal under the Decisional Bilinear Diffie–Hellman assumption in the standard model.

개선된 원 라운드 인증 그룹 키 합의 프로토콜

많은 인증 키 합의 프로토콜이 제안되어 왔다. 여전히 안전한 인증키 합의 프로토콜을 설계하는 것이 이슈화되고 있다. 이 논문에서는, 전형적인 ID 기반의 암호화 시스템의 공개키와 개인키 뿐 아니라 하나 더 많은 공개키와 개인키를 사용하는 원 라운드 인증 그룹키 합의 프로토콜을 제안한다. 제안된 프로토콜은 Shi et al. 프로토콜과 He et al. 프로토콜을 수정 보완하였다. 제안된 프로토콜의 공개키 개인키와 서명 과정은 그들의 프로토콜보다 단순하다. 제안한 프로토콜은 안전하며, 통신과 계산 비용 면에서 그들의 프로토콜보다 더 효율적이다. Several identity-based and authenticated key agreement protocols have been proposed. It remains at issue to design secure identity based and authenticated key agreement protocols. In this paper, we propose a one round authenticated group key agreement protocol which uses one more key pair as well as the public key and private key of typical IBE(Identity-Based Encryption) system. The proposed protocol modified Shi et al.'s protocol and He et al.'s protocol. The public and private keys and the signature process of our protocol are simpler than them of their protocols. Our protocol is secure and more efficient than their protocols in communication and computation costs.

On the Anonymity of Identity-Based Encryption

Anonymity of identity-based encryption (IBE) means that given a ciphertext, one cannot distinguish the target identity from a random identity. In this paper, we thoroughly discuss the anonymity of IBE systems. We found that the current definition of anonymity is obscure to describe some IBE systems, such as Gentry IBE system. Furthermore, current definition cannot express the degree of anonymity. So we divide the degree of anonymity into weak anonymity and strong anonymity based on indistinguishability between different games. For weakly anonymous IBE systems, the target identity in a ciphertext cannot be distinguished from a random identity. For strongly anonymous IBE systems, the whole ciphertext cannot be distinguished from a random tuple. We also discuss the type of anonymity and divide it into two types. Type 1 means that a random tuple can be seen as a valid ciphertext, while type 2 cannot. Based on our new definitions, we show that three famous IBE systems, Gentry IBE system, Boyen-Waters IBE system, and Lewko IBE system, have strong but different types of anonymity.

Practical distributed secret key generation for delay tolerant networks

SUMMARYDelay tolerant networks (DTNs) are resource‐constrained dynamic networks where a continuous end‐to‐end connectivity is not always available. In such a challenging network, a fixed infrastructure may not be connected when a DTN is partitioned or the message delay in the network is large. Thus, the traditional public key infrastructure system and identity‐based encryption (IBE) system are not suitable for DTNs because they rely on centralized infrastructures and require multiple round‐trip interactions. To address this issue, we propose a distributed secret key generation system with self‐certified identity (SCI‐DKG) that does not require any private key generator and threshold cryptosystem. Initially, each node generates a private key and distributes an initial message including a self‐certified identity and secret sharings to members in a DTN. Receivers independently authenticate the identity and extracts some encryption parameters corresponding to the identity from this initial message. We prove that SCI‐DKG is chosen ciphertext secure in the standard model, and it can resist potential network attacks. Simulation results show that SCI‐DKG has smaller delay and higher successful ratio of secret key generation compared with IBE and hierarchical IBE systems implemented in a DTN. Copyright © 2012 John Wiley & Sons, Ltd.

Unified Authentication Scheme Based on IBE in Trusted Network

The existing unified authentication schemes are based on Public Key Infrastructure (PKI)/Privilege Management Infrastructure (PMI), WS-Security, Kerberos etc. But they can't support the developing Trusted Network Connect (TNC) environment. To solve the problem, a unified authentication scheme supporting multi-authentication modes based on Identity-Based Encryption (IBE) in trusted network named IEUAS is proposed. IEUAS authenticates the identity of a user by loading different authentication plugins to communicate with the related authentication servers. According to the legal identity of the user, a lightweight IBE system enforces four management mechanisms. They are the identity management, the key management, the application management and the domain management. Single Sign-On (SSO) and cross-domain SSO are implemented. The experiment results show that IEUAS can effectively solve the unified authentication problem in the TNC environment, and provide better security, efficiency and availability.

A provable secure fuzzy identity based signature scheme

To use biometrics identities in an identity based encryption system, Sahai and Waters first introduced the notion of fuzzy identity based encryption (FIBE) in 2005. Yang et al. extended it to digital signature and introduced the concept of fuzzy identity based signature (FIBS) in 2008, and constructed an FIBS scheme based on Sahai and Waters’s FIBE scheme. In this paper, we further formalize the notion and security model of FIBS scheme and propose a new construction of FIBS scheme based on bilinear pairing. The proposed scheme not only provides shorter public parameters, private key and signature, but also have useful structures which result in more efficient verification than that of Yang et al.’s FIBS scheme. The proposed FIBS scheme is proved to be existentially unforgeable under a chosen message attack and selective fuzzy identity attack in the random oracle model under the discrete logarithm assumption.

Fuzzy Techniques in Biometric IBE without Random Oracles

Using a biometric as an identity has the advantage that identities are unique if the underlying biometric is of a good quality, such as fingerprints, faces, irises. Since biometric measurements are noisy, the existing identity-based encryption systems cannot be used directly to construct IBE scheme. The error-tolerance property of Fuzzy-IBE allows for a private key to decrypt a ciphertext encrypted with a slightly different measurement of the same biometric. Based on this property, a new biometric identity based encryption scheme is proposed. Our scheme is constructed in the standard model and achieves a selective identity security. In addition, the security of our scheme is reduced to decision bilinear Diffie-Hellman(BDH) assumption instead of other strong assumptions.