Anonymous Identity-based Encryption Research Articles

Anonymous hierarchical identity-based encryption with delegated traceability for cloud-based data sharing systems

Cloud-based data sharing systems (DSS) have become prevalent due to their ample storage and convenient access control. To protect sensitive data privacy in DSS, anonymous identity-based encryption (IBE) is a promising approach, enabling encryption using a recipient’s identity as a public key, while preventing identity and data leaks out of ciphertexts. As complete anonymity risks abuse and illegal usage, Blazy et al. introduced the notion called anonymous IBE with traceable identities (AIBET) at ARES’19, allowing users with tracing keys to identify recipients from ciphertexts. Unfortunately, existing AIBET schemes lack tracing key delegation and only consider security in weaker models (i.e., selective-identity attacks and chosen-plaintext attacks), posing risks of inconvenience and user privacy leaks. In this paper, we introduce a novel notion called anonymous hierarchical identity-based encryption with delegated traceability (AHIBEDT) for DSS. We formalize its syntax and define security notions in stronger models (i.e., adaptive-identity attacks and chosen-ciphertext attacks). In addition, we demonstrate that a concrete AHIBEDT scheme can be simply obtained from a hierarchical IBE scheme and a one-time signature scheme. The comparison results indicate that, despite a substantial increase in communication and computational costs, our approach achieves better security and functionality.

A computer-aided feature-based encryption model with concealed access structure for medical Internet of Things

One of the Internet of Things (IoT) security issues is the secure sharing and granular management of data access. This study recommends a feature-based encryption scheme with a hidden access structure for medical IoT data security. While establishing fine-grained access control of ciphertext data, the system can guarantee clinical client data privacy. First, it is recommended to convert identity-based encryption (IBE) into a feature-based encryption model (FBEM) using a universal conversion technique that supports multi-valued attributes and gates. IBE characteristics could be inherited by the converted FBEM. The conversion method is then used to change the receiver anonymous IBE scheme into the FBEM scheme with concealed access structure. The FBEM model is then used to construct the IoT scenario for the smart medical application. Theoretical analysis and experimental findings reveal that the suggested system provides advantages over prominent systems regarding computing efficiency, storage load, and security when the access structure is disguised.

Anonymous Homomorphic IBE with Application to Anonymous Aggregation

All anonymous identity-based encryption (IBE) schemes that are group homomorphic (to the best of our knowledge) require knowledge of the identity to compute the homomorphic operation. This paper is motivated by this open problem, namely to construct an anonymous group-homomorphic IBE scheme that does not sacrifice anonymity to perform homomorphic operations. Note that even when strong assumptions, such as indistinguishability obfuscation (iO), are permitted, no schemes are known. We succeed in solving this open problem by assuming iO and the hardness of the DBDH problem over rings (specifically, ZN2 for RSA modulus N). We then use the existence of such a scheme to construct an IBE scheme with re-randomizable anonymous encryption keys, which we prove to be IND-ID-RCCA secure. Finally, we use our results to construct identity-based anonymous aggregation protocols.

Quantum-safe Anonymous Hierarchical Identity-Based Encryption with Traceable Identities

Anonymous Identity Based Encryption (AIBET) scheme allows a tracer to use the tracing key to reveal the recipient’s identity from the ciphertext while keeping other data anonymous. This special feature makes AIBET a promising solution to distributed IoT data security since it can preserve both the privacy and the anonymity of a communication network but still give the server the ability to revoke the anonymity of some specific users in necessary situations (such as when their illegal behavior are detected). In this paper, we construct an efficient quantum-safe Hierarchical Identity-Based cryptosystem with Traceable Identities (AHIBET) with fully anonymous ciphertexts. We prove the security of our AHIBET scheme under the Learning with Errors (LWE) problem in the standard model.

Erratum: Quantum‐resistant anonymous identity‐based encryption with traceable identities

IET Information SecurityVolume 16, Issue 6 p. 482-482 ERRATUMOpen Access Erratum: Quantum-resistant anonymous identity-based encryption with traceable identities This article corrects the following: Quantum-resistant anonymous identity-based encryption with trable identities Zi-Yuan Liu, Yi-Fan Tseng, Raylin Tso, Masahiro Mambo, Yu-Chi Chen, Volume 16Issue 2IET Information Security pages: 111-126 First Published online: November 23, 2021 First published: 27 May 2022 https://doi.org/10.1049/ise2.12069AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat In Ref. [1], the following corrections should be noted. The title of the article should be as below: Quantum-resistant anonymous identity-based encryption with traceable identities REFERENCE 1Liu, Z.-Y., et al.: Quantum-resistant anonymous identity-based encryption with traceable identities. IET Inf. Secur. 16(2), 111– 126 (2022). https://doi.org/10.1049/ise2.12049 Volume16, Issue6November 2022Pages 482-482 ReferencesRelatedInformation

Quantum‐resistant anonymous identity‐based encryption with trable identities

Identity-based encryption (IBE), introduced by Shamir, eliminates the need for public-key infrastructure. The sender can simply encrypt a message by using the recipient's identity (such as email or IP address) without needing to look up the public key. In particular, when ciphertexts of an IBE do not reveal recipient's identity, this scheme is known as an anonymous IBE scheme. Recently, Blazy et al. (ARES '19) analysed the trade-off between public safety and unconditional privacy in anonymous IBE and introduced a new notion that incorporates traceability into anonymous IBE, called anonymous IBE with traceable identities (AIBET). However, their construction is based on the discrete logarithm assumption, which is insecure in the quantum era. In this paper, we first formalize the consistency of tracing key of the AIBET scheme to ensure that a ciphertext cannot be traced with the use of wrong tracing keys. Subsequently, we present a generic formulation concept that can be used to transform structure-specific lattice-based anonymous IBE schemes into an AIBET. Finally, we apply this concept to Katsumata and Yamada's compact anonymous IBE scheme (Asiacrypt '16) to obtain the first quantum-resistant AIBET scheme that is adaptively secure under the ring learning with errors assumption without random oracle.

Generalized Galbraith’s Test: Characterization and Applications to Anonymous IBE Schemes

The main approaches currently used to construct identity-based encryption (IBE) schemes are based on bilinear mappings, quadratic residues and lattices. Among them, the most attractive approach is the one based on quadratic residues, due to the fact that the underlying security assumption is a well-understood hard problem. The first such IBE scheme was constructed by Cocks, and some of its deficiencies were addressed in subsequent works. In this paper, we focus on two constructions that address the anonymity problem inherent in Cocks’ scheme, and we tackle some of their incomplete theoretical claims. More precisely, we rigorously study Clear et al.’s and Zhao et al.’s schemes and give accurate probabilities of successful decryption and identity detection in the non-anonymized version of the schemes. Furthermore, in the case of Zhao et al.’s scheme, we give a proper description of the underlying security assumptions.

Practical Inner Product Encryption with Constant Private Key

Inner product encryption, first introduced by Katz et al., is a type of predicate encryption in which a ciphertext and a private key correspond to an attribute vector and a predicate vector, respectively. Only if the attribute and predicate vectors satisfy the inner product predicate will the decryption in this scheme be correct. In addition, the ability to use inner product encryption as an underlying building block to construct other useful cryptographic primitives has been demonstrated in the context of anonymous identity-based encryption and hidden vector encryption. However, the computing cost and communication cost of performing inner product encryption are very high at present. To resolve this problem, we introduce an efficient inner product encryption approach in this work. Specifically, the size of the private key is only one G element and one Zp element, and decryption requires only one pairing computation. The formal security proof and implementation result are also demonstrated. Compared with other state-of-the-art schemes, our scheme is the most efficient in terms of the number of pairing computations for decryption and the private key length.

Generic Construction of Adaptively Secure Anonymous Key-Policy Attribute-Based Encryption from Public-Key Searchable Encryption

Public-key encryption with keyword search (PEKS) is a cryptographic primitive that allows us to search encrypted data for those of including particular keywords without decrypting them. PEKS is expected to be used for enhancing security of cloud storages. It is known that PEKS can be constructed from anonymous identity-based encryption (IBE), anonymous attribute-based encryption (ABE) and so on. It is believed that it is difficult to construct PEKS schemes that can specify a flexible search condition such as logical disjunctions and logical conjunctions from weaker cryptographic tools than ABE. However, this intuition has not been rigorously justified. In this paper, we formally prove it by constructing key-policy ABE from PEKS for monotone boolean formulas.

Anonymous and Updatable Identity-Based Hash Proof System

In EUROCRYPT 2002, Alwen et al. demonstrated that an identity-based hash proof system (IB-HPS) can be used to generate an identity-based encryption (IBE) scheme, which is secure against partial leakage of the decryption key of the target identity. However, in many real-world applications, the leakage is normally unbounded, and an adversary could violate the security of such cryptography schemes by performing continuous leakage attacks. Therefore, cryptography schemes are desirable to maintain their claimed security even in the continuous leakage setting. In this paper, we first design an improved IB-HPS called updatable IB-HPS (U-IB-HPS), which has an additional key update algorithm to embed some fresh randomness into the user's private key, ensuring that enough entropy is maintained in the updated keys. Then, we further use the U-IB-HPS to propose a generic construction of continuously leakage-resilient IBE schemes. Finally, an instantiation of the U-IB-HPS with anonymity is presented. As a result, our construction delivers an anonymous IBE scheme that is secure against continuous leakage of user's private key. The security of our proposed scheme has been proved in the random oracle model under the classic decisional bilinear Diffie–Hellman assumption, which is a standard static security assumption.

A Generic Construction of Integrated Secure-Channel Free PEKS and PKE and its Application to EMRs in Cloud Storage.

To provide a search functionality for encrypted data, public key encryption with keyword search (PEKS) has been widely recognized. In actual usage, a PEKS scheme should be employed with a PKE scheme since PEKS itself does not support the decryption of data. Since a naive composition of a PEKS ciphertext and a PKE ciphertext does not provide CCA security, several attempts have been made to integrate PEKS and PKE in a joint CCA manner (PEKS/PKE for short). In this paper, we further extend these works by integrating secure-channel free PEKS (SCF-PEKS) and PKE, which we call SCF-PEKS/PKE, where no secure channel is required to send trapdoors. We give a formal security definition of SCF-PEKS/PKE in a joint CCA manner, and propose a generic construction of SCF-PEKS/PKE based on anonymous identity-based encryption, tag-based encryption, and one-time signature. We also strengthen the current consistency definition according to the secure-channel free property, and show that our construction is strongly consistent if the underlying IBE provides unrestricted strong collision-freeness which is defined in this paper. We also show that such an IBE scheme can be constructed by employing the Abdalla et al. transformations (TCC 2010/J. Cryptology 2018). Finally, as an application of SCF-PEKS/PKE, we strengthen the security of encrypted Electronic Medical Record (EMR) system proposed by Guo and Yau (J. Medical Sys. 2015).

Anonymous Communication via Anonymous Identity-Based Encryption and Its Application in IoT

Under the environment of the big data, the correlation between the data makes people have a greater demand for privacy. Moreover, the world has become more diversified and democratic than ever before. Freedom of speech is considered to be very important; thus, anonymity is also a very important security demand. The research of our paper proposes a scheme which can ensure both the privacy and the anonymity of a communication system, that is, the protection of message privacy while ensuring the users’ anonymity. It is based on anonymous identity-based encryption (IBE), by which the users’ metadata are protected. We implement our scheme in JAVA with Java pairing-based cryptography library (JPBC); the experiment shows that our scheme has significant advantage in efficiency compared with other anonymous communication system. Internet-of-Things (IoT) involves many devices, and privacy of devices is very significant. Anonymous communication system provides a secure environment without leaking metadata, which has many application scenarios in IoT.

Noninteractive Verifiable Outsourcing Algorithm for Bilinear Pairing with Improved Checkability

It is well known that the computation of bilinear pairing is the most expensive operation in pairing-based cryptography. In this paper, we propose a noninteractive verifiable outsourcing algorithm of bilinear pairing based on two servers in the one-malicious model. The outsourcer need not execute any expensive operation, such as scalar multiplication and modular exponentiation. Moreover, the outsourcer could detect any failure with a probability close to 1 if one of the servers misbehaves. Therefore, the proposed algorithm improves checkability and decreases communication cost compared with the previous ones. Finally, we utilize the proposed algorithm as a subroutine to achieve an anonymous identity-based encryption (AIBE) scheme with outsourced decryption and an identity-based signature (IBS) scheme with outsourced verification.

Public‐key encryption with keyword search secure against continual memory attacks

AbstractContinual memory attacks, inspired by recent realistic physical attacks, have broken many cryptographic schemes that were considered secure in traditional cryptography model. In this paper, we consider the continual memory leakage resilience in public‐key encryption with keyword search scheme (PEKS). We give the definition of continual memory leakage resilience security for PEKS, which allows continual secret key leakage in the trapdoor generation algorithm rather than leakage of trapdoor itself. We believe that the definition is more suitable for practical PEKS scenario. To construct a concrete PEKS scheme secure against continual memory attacks, we firstly obtain a continual master‐key leakage‐resilient anonymous identity‐based encryption (IBE) scheme by applying the generic tool provided by Lewko et al. to a fully secure anonymous IBE scheme that comes from the fully secure anonymous hierarchical identity‐based encryption (HIBE) scheme of De Caro and colleagues. Then, we transform our continual master‐key leakage‐resilient anonymous IBE scheme to a PEKS scheme using the generic Anonymous IBE‐to‐PEKS transformation and prove its continual leakage‐resilient security. Copyright © 2016 John Wiley & Sons, Ltd.

Generating Searchable Public-Key Ciphertexts With Hidden Structures for Fast Keyword Search

Existing semantically secure public-key searchable encryption schemes take search time linear with the total number of the ciphertexts. This makes retrieval from large-scale databases prohibitive. To alleviate this problem, this paper proposes Searchable Public-Key Ciphertexts with Hidden Structures (SPCHS) for keyword search as fast as possible without sacrificing semantic security of the encrypted keywords. In SPCHS, all keyword-searchable ciphertexts are structured by hidden relations, and with the search trapdoor corresponding to a keyword, the minimum information of therelations is disclosed to a search algorithm as the guidance to find all matching ciphertexts efficiently. We construct a simple SPCHS scheme from scratch in which the ciphertexts have a hidden star-like structure. We prove our scheme to be semantically secure based on the decisional bilinear Diffie-Hellman assumption in the Random Oracle (RO) model. The search complexity of our scheme is dependent on the actual number of the ciphertexts containing the queried keyword, rather than the number of all ciphertexts. Finally, we present a generic SPCHS construction from anonymous identity-based encryption and collision-free full-identity malleable Identity-Based Key Encapsulation Mechanism (IBKEM) with anonymity. We illustrate two collision-free full-identity malleable IBKEM instances, which are semantically secure and anonymous, respectively, in the RO and standard models. The latter instance enables us to construct an SPCHS scheme with semantic security in the standard model.

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.

Generic constructions of integrated PKE and PEKS

In this paper we investigate the topic of integrated public-key encryption (PKE) and public-key encryption with keyword search (PEKS) schemes (PKE---PEKS as shorthand). We first formalize the strongest security notion to date for PKE---PEKS schemes, named joint CCA-security. We then propose two simple constructions of jointly CCA-secure PKE---PEKS schemes from anonymous (hierarchical) identity-based encryption schemes. Besides, we also define the notion of consistency for PKE---PEKS schemes, as well as revisit its related notions (including consistency of PEKS schemes, robustness and collision-freeness of IBE schemes), which may be of independent interest.

Public-Key Encryption with Fuzzy Keyword Search: A Provably Secure Scheme under Keyword Guessing Attack

Public-key encryption with keyword search (PEKS) is a versatile tool. It allows a third party knowing the search trapdoor of a keyword to search encrypted documents containing that keyword without decrypting the documents or knowing the keyword. However, it is shown that the keyword will be compromised by a malicious third party under a keyword guess attack (KGA) if the keyword space is in a polynomial size. We address this problem with a keyword privacy enhanced variant of PEKS referred to as public-key encryption with fuzzy keyword search (PEFKS). In PEFKS, each keyword corresponds to an exact keyword search trapdoor and a fuzzy keyword search trapdoor. Two or more keywords share the same fuzzy keyword trapdoor. To search encrypted documents containing a specific keyword, only the fuzzy keyword search trapdoor is provided to the third party, i.e., the searcher. Thus, in PEFKS, a malicious searcher can no longer learn the exact keyword to be searched even if the keyword space is small. We propose a universal transformation which converts any anonymous identity-based encryption (IBE) scheme into a secure PEFKS scheme. Following the generic construction, we instantiate the first PEFKS scheme proven to be secure under KGA in the case that the keyword space is in a polynomial size.

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.

Searchable Encryption Revisited: Consistency Properties, Relation to Anonymous IBE, and Extensions

We identify and fill some gaps with regard to consistency (the extent to which false positives are produced) for public-key encryption with keyword search (PEKS). We define computational and statistical relaxations of the existing notion of perfect consistency, show that the scheme of Boneh et al. (Advances in Cryptology—EUROCRYPT 2004, ed. by C. Cachin, J. Camenisch, pp. 506–522, 2004) is computationally consistent, and provide a new scheme that is statistically consistent. We also provide a transform of an anonymous identity-based encryption (IBE) scheme to a secure PEKS scheme that, unlike the previous one, guarantees consistency. Finally, we suggest three extensions of the basic notions considered here, namely anonymous hierarchical identity-based encryption, public-key encryption with temporary keyword search, and identity-based encryption with keyword search.