Anonymous Hierarchical 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.

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.

Enhanced TBAHIBE-LBKQS techniques for privacy preservation in cloud

In recent days, providing security to the data stored in cloud is an important and challenging task. The existing works have some drawbacks such as, high cost, required more amount of time for execution and low level security. So, this paper proposes novel techniques such as, tiered blind and anonymous hierarchical identity-based encryption (TBAHIBE) and location-based keyword query search (LBKQS) for privacy preservation. In this work, the privacy is provided to the medical data stored in the electronic health record (EHR). Here, the medical data of the egg and sperm donor, receptor, doctor and lab technician are stored in an encrypted format by using the proposed TBAHIBE technique. Then, the location-based search is enabled based on the keyword and query. The experimental results evaluate the performance in terms of computation cost, communication cost, query evaluation, encryption time, decryption time and key generation time.

Enhanced TBAHIBE-LBKQS techniques for privacy preservation in cloud

In recent days, providing security to the data stored in cloud is an important and challenging task. The existing works have some drawbacks such as, high cost, required more amount of time for execution and low level security. So, this paper proposes novel techniques such as, tiered blind and anonymous hierarchical identity-based encryption (TBAHIBE) and location-based keyword query search (LBKQS) for privacy preservation. In this work, the privacy is provided to the medical data stored in the electronic health record (EHR). Here, the medical data of the egg and sperm donor, receptor, doctor and lab technician are stored in an encrypted format by using the proposed TBAHIBE technique. Then, the location-based search is enabled based on the keyword and query. The experimental results evaluate the performance in terms of computation cost, communication cost, query evaluation, encryption time, decryption time and key generation time.

Cryptanalysis of a Compact Anonymous HIBE with Constant Size Private Keys

AbstractRecently, Zhang et al. proposed a new anonymous hierarchical identity-based encryption (anonymous HIBE) over prime order groups to achieve both constant size private key and constant size ciphertext. Moreover, a double exponent technique was used to provide anonymity. They proved that their scheme is secure and anonymous against chosen plaintext attacks in the standard model. In this paper, we point out that their scheme is insecure.

A Secure and Privacy-Aware Smart Health System with Secret Key Leakage Resilience

With the development of the smart health (s-health), data security and patient privacy are becoming more and more important. However, some traditional cryptographic schemes can not guarantee data security and patient privacy under various forms of leakage attacks. To prevent the adversary from capturing the part of private keys by leakage attacks, we propose a secure leakage-resilient s-health system which realizes privacy protection and the safe transmission of medical information in the case of leakage attacks. The key technique is a promising public key cryptographic primitive called leakage-resilient anonymous Hierarchical Identity-Based Encryption. Our construction is proved to be secure against chosen plaintext attacks in the standard model under the Diffie-Hellman exponent assumption and decisional linear assumption. We also blind the public parameters and ciphertexts by using double exponent technique to achieve the recipient anonymity. Finally, the performance analysis shows the practicability of our scheme, and the leakage rate of the private key approximates to 1/6.

Anonymous hierarchical identity-based encryption with bounded leakage resilience and its application

Hierarchical identity-based encryption can be used to protect the sensitive data in cloud system. However, as the traditional security model does not capture side-channel attacks, many hierarchical identity-based encryption schemes do not resist this kind of attack, which can exploit various forms of unintended information leakage. Inspired by these, leakage-resilience cryptography formalises some models of side-channel attacks. In this paper, we consider the memory leakage resilience in anonymous hierarchical identity-based encryption schemes. By applying Lewko et al.'s tools, we construct a master key leakage-resilient anonymous hierarchical identity-based encryption scheme based on dual system encryption techniques. As an interesting application of our scheme, we consider security for public-key encryption with multi-keyword ranked search (PEMKRS) in the presence of secret key leakage in the trapdoor generation algorithm, and provide a generic construction of leakage-resilient secure PEMKRS from a master key leakage-resilient anonymous hierarchical identity-based encryption scheme.

Anonymous hierarchical identity-based encryption with bounded leakage resilience and its application

Hierarchical identity-based encryption can be used to protect the sensitive data in cloud system. However, as the traditional security model does not capture side-channel attacks, many hierarchical identity-based encryption schemes do not resist this kind of attack, which can exploit various forms of unintended information leakage. Inspired by these, leakage-resilience cryptography formalises some models of side-channel attacks. In this paper, we consider the memory leakage resilience in anonymous hierarchical identity-based encryption schemes. By applying Lewko et al.'s tools, we construct a master key leakage-resilient anonymous hierarchical identity-based encryption scheme based on dual system encryption techniques. As an interesting application of our scheme, we consider security for public-key encryption with multi-keyword ranked search (PEMKRS) in the presence of secret key leakage in the trapdoor generation algorithm, and provide a generic construction of leakage-resilient secure PEMKRS from a master key leakage-resilient anonymous hierarchical identity-based encryption scheme.

Compact Anonymous Hierarchical Identity-Based Encryption with Constant Size Private Keys: TABLE 1.

We present a new construction of anonymous hierarchical identity-based encryption (HIBE) over prime order groups. The distinct feature of our proposed scheme is that both private key and ciphertext have a constant size, which has never been achieved in all other existing anonymous HIBE schemes. Moreover, we utilized a double exponent technique to generate the ciphertext in order to provide anonymity. This simple and efficient method allows us to construct a more compact anonymous HIBE in prime order groups. Under the decisional bilinear |$n+1$|-Diffie–Hellman exponent assumption and linear assumption, we show that the proposed scheme is secure and anonymous against chosen plaintext attacks 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.

Multi-keyword ranked searchable public-key encryption

Most related works on Public-Key Encryption with Keyword Search scheme also called Searchable Public-key Encryption focus on single keyword search. Some works supporting multi-keyword search cannot provide search result ranking. In this paper, we study the problem of multi-keyword ranked search over encrypted data in public-key model. We propose the definition of Multi-Keyword Ranked Searchable Public-key Encryption/Public-Key Encryption with Multi-Keyword Ranked Search. In the definition, we allow the receiver to query any set of keywords. As the query result, the receiver can get the number of queried keywords appearing in the encrypted data, which can be used to evaluate the similarity ranking of the data keywords to the search query in 'as many matches as possible' principle. We put forward a generic construction for public-key encryption with multi-keyword ranked search scheme with sub-linear ciphertext based on any anonymous hierarchical identity-based encryption scheme and provide the security analysis. At last, we present a concrete scheme with sub-linear ciphertext.

Unbounded Anonymous Hierarchical Identity-Based Encryption in the Standard Model

In this work, we present a new anonymous HIBE scheme which is unbounded in the sense that the public parameters do not impose additional limitations on the functionality of the systems. In most of previous constructions of anonymous HIBE in the standard model, a maximum hierarchy depth had to be fixed at setup. Our constructions avoid these limitations. We use a nested dual system encryption argument to prove full security for our anonymous HIBE scheme, in the standard model and relying on static assumptions.

Unbounded anonymous hierarchical IBE with continual-key-leakage tolerance

Modern cryptographic schemes are constructed under the fundamental assumption that secret keys are perfectly hidden from all possible attackers. In practice, however, keys and internal states may partially be leaked. Recently, cryptographic construction with key-leakage resilience has been a crucial research topic. In this work, we proposed an anonymous hierarchical identity-based encryption that can tolerate partial leakage of secret keys. Our results were as follows. First, we provided a tolerance for continual key leakage that can capture both memory leakage and continual leakage. We extended a dual-system encryption mechanism in orthogonal subgroups to achieve key-leakage resilience and implicitly employed an update algorithm to guard against continual leakage. Second, the delegation depth is unbounded, which means that no predetermined depth was imposed in the setup algorithm, thus making the scheme very flexible in practice. We employed a secret-sharing approach to split the master key into multiple shares in key components corresponding to the elements. Third, we analyzed and discussed the performance of allowable leakage-tolerance bounds and the leakage rate of the proposed scheme and gave an evaluation that attains about 40-70% leakage rate under the Advanced Encryption Standard 112 security level. Copyright © 2013 John Wiley & Sons, Ltd.

Anonymous HIBE with short ciphertexts: full security in prime order groups

Anonymous Hierarchical Identity-Based Encryption (HIBE) is an extension of Identity-Based Encryption (IBE), and it provides not only a message hiding property but also an identity hiding property. Anonymous HIBE schemes can be applicable to anonymous communication systems and public key encryption systems with keyword searching. However, previous anonymous HIBE schemes have some disadvantages that the security was proven in the weaker model, the size of ciphertexts is not short, or the construction was based on composite order bilinear groups. In this paper, we propose the first efficient anonymous HIBE scheme with short ciphertexts in prime order (asymmetric) bilinear groups, and prove its security in the full model with an efficient reduction. To achieve this, we use the dual system encryption methodology of Waters. We also present the benchmark results of our scheme by measuring the performance of our implementation.

Anonymous HIBE: Compact Construction Over Prime-Order Groups

We present an anonymous hierarchical identity based encryption (HIBE) scheme that not only achieves constant-size ciphertext, but also works in bilinear groups with prime order. In contrast to our work, all previous anonymous HIBE schemes either have ciphertext size linear in the depth of the hierarchy or work in bilinear groups with a composite order. Our construction is more efficient than previous schemes in terms of ciphertext size and decryption cost. We give provable security of our construction, consisting of confidentiality and anonymity, without random oracles. To gain anonymity, we introduce a novel and simple method called “double exponent” technique, which gives an anonymous HIBE scheme more compact than the result at CRYPTO 2006. Our method is quite general in that it works on both symmetric and asymmetric bilinear maps. The simple method might also be of independent interest to gain anonymity of attributes in constructing searchable encryption schemes on encrypted data.

Anonymous Hierarchical Identity-Based Encryption with Short Ciphertexts

We propose an anonymous Hierarchical Identity-Based Encryption (anonymous HIBE) scheme with short ciphertexts. Prior to our work, most anonymous HIBE schemes have long ciphertexts increased according to the hierarchical depth of recipient. The size of the ciphertext in our scheme does not depend on the depth of the hierarchy. Moreover, our scheme achieves the lowest computational cost because during the decryption phase the computational cost of decryption is constant. The security can be proven under reasonable assumptions without using random oracles. Our scheme achieves selective-ID security notion.

New Techniques for Anonymous HIBE with Short Ciphertexts in Prime Order Groups

Anonymous hierarchical identity based encryption (HIBE) is an extension of identity based encryption (IBE) that can use an arbitrary string like an e-mail address for a public key, and it additionally provide the anonymity of identity in ciphertexts. Using the anonymous HIBE schemes, it is possible to construct anonymous communication systems and public key encryption with keyword search. This paper presents an anonymous HIBE scheme with constant size ciphertexts under prime order symmetric bilinear groups, and shows that it is secure under the selective security model. Previous anonymous HIBE schemes were constructed to have linear size ciphertexts, to use composite order bilinear groups, or to use asymmetric bilinear groups that is a special type of bilinear groups. Our construction is the first efficient anonymous HIBE scheme that has constant size ciphertexts and that uses prime order symmetric bilinear groups. Compared to the previous scheme of composite order bilinear groups, ours is ten times faster. To achieve our construction, we first devise a novel cancelable random blinding technique. The random blinding property of our technique provides the anonymity of our construction, and the cancellation property of our technique enables decryption.

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.