Dual System Encryption Technique Research Articles

A direct construction of continuous leakage-resilient (H)IBE scheme with CCA security from dual system encryption

Continuous leakage resilient semantically secure Identity-based Encryption (IBE) schemes created with dual system encryption technique were presented by Lewko et al. at TCC 2011 and Yuen et al. at Eurocrypt 2012, respectively. It has been a research challenge to achieve the security against chosen-ciphertext attacks (CCA). The previous attempts toward the CCA security rely on q-type assumptions, which are referred as non-static assumptions causing loose reduction in security proofs. In this paper, we provide a complete solution to the problem and show how to construct the continuous leakage-resilient IBE with weaker CCA security based on the dual system encryption technique, where the adversary is allowed to make continuous leakage queries. We are able to prove its security with static assumptions in the standard model. As a feature of our scheme, we allow leakage of multiple keys, i.e., leakage of the master secret key and the private key of user. Our scheme also enjoys better computational performance, since the round leakage parameter is independent of the plaintext space and has a constant size. Furthermore, our scheme can be easily extended to give the weaker CCA secure continuous leakage-resilient hierarchical identity-based encryption scheme with a short ciphertext length.

Efficient Hierarchical Identity-Based Encryption System for Internet of Things Infrastructure

Security is a main concern for the Internet of Things (IoT) infrastructure as large volumes of data are collected and processed in the systems. Due to the limited resources of interconnected sensors and devices in the IoT systems, efficiency is one of the key considerations when deploying security solutions (e.g., symmetric/asymmetric encryption, authentication, etc.) in IoT. In this paper, we present an efficient Hierarchical Identity-Based Encryption (HIBE) system with short parameters for protecting data confidentiality in distributed IoT infrastructure. Our proposed HIBE system has the public parameters, private key, and ciphertext, each consisting of a constant number of group elements. We prove the full security of the HIBE system in the standard model using the dual system encryption technique. We also implement the proposed scheme and compare the performance with the original Lewko–Waters HIBE. To the best of our knowledge, our construction is the first HIBE system that achieves both full security in the standard model and short parameters in terms of the public parameters, private key, and ciphertext.

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.

Leakage-Resilient Hierarchical Identity-Based Encryption with Recipient Anonymity

As a promising public key cryptographic primitive, hierarchical identity-based encryption (HIBE) introduces key delegation mechanisms into identity-based encryption. However, key leakage and recipient anonymity issues have not been adequately addressed in HIBE. Hence, direct applications of traditional HIBE schemes will violate data security and abuse users’ privacy in practice. In this paper, we propose an anonymous unbounded hierarchical identity-based encryption scheme, which achieves bounded leakage resilience and the hierarchy depth is not limited. Our security proofs based on the dual system encryption technique show that the proposed scheme is capable of resisting key leakage and it realizes recipient anonymity in the standard model. In addition, leakage resilience analysis indicates that our scheme allows the leakage rate of approximate 1/3 no matter the hierarchy depth of identities. Finally, performance comparisons show the practicability of our scheme. In particular, the secret key of our construction is of a fixed-length.

Hierarchical attribute based encryption with continuous leakage-resilience

Attribute based encryption (ABE) is widely applied in cloud computing settings due to its fine-grained access control. Most ABE schemes do not consider the side channel attacks which may leak the secret information of cryptosystems. Leakage-resilient cryptography aims to model security for various side channel attacks. In this paper, we first give the formal definition and security model of hierarchical attribute based encryption (HABE) with continuous leakage-resilience. Furthermore, we present a ciphertext-policy HABE scheme with continuous leakage-resilience. The proposed scheme is resilient to master key leakage and secret key leakage. We prove the security of our scheme under composite order bilinear group assumptions by using dual system encryption techniques. The performance of leakage-resilience is analyzed theoretically. If the depth of our proposed scheme is 1, the relative leakage ratio is almost up to 1/3. In addition, we give the performance comparison through experiments.

Correction to “Improving Privacy and Security in Decentralizing Multi-Authority Attribute-Based Encryption in Cloud Computing”

In 2018, Yang et al. proposed a decentralized multi-authority attribute-based encryption scheme for cloud computing applications and proved its security using the dual system encryption technique. In this comment, we show that Yang et al. ’s scheme does not achieve encryption one-wayness under the key-only attack and the user collusion attack, respectively. In the key-only attack, with the knowledge of public parameters only, an adversary can impersonate the attribute authorities to forge user attribute secret keys. In the user collusion attack, malicious users can collude by sharing their secret keys to unauthorizedly decrypt a ciphertext. In order to fix the scheme, we suggest adopting a pairing-based proof of knowledge protocol and the decryption algorithm from Lewko and Water’s ABE scheme.

Identity-based broadcast encryption with continuous leakage resilience

Identity-based broadcast encryption (IBBE) is an important type of broadcast encryption. In the paper, we put forward the formal definition and security model of IBBE with leakage-resilience. Furthermore, we propose an IBBE scheme with continuous leakage-resilience. The presented scheme is resilient to private key leakage. By refreshing the private key, our scheme can resist continuous private key leakage. Based on dual system encryption technique, we prove the security of the proposed scheme under subgroup decisional assumptions. We give the specific performance analysis of leakage-resilience. The relative leakage ratio can amount to 1/3.

An Attribute-Based Anonymous Broadcast Encryption Scheme with Adaptive Security in the Standard Model

In broadcast encryption schemes, a distribution center broadcasts an encrypted message to a subset chosen from a universe of receivers and only the intended users are able to decrypt the message. Most broadcast encryption schemes do not provide anonymity and the identities of target receivers are sent in plaintext. However, in several applications, the authorized users’ identities have the same sensitivity as the broadcasted messages. Yu, Ren and Lou (YRL) considered this issue and introduced an e€icient anonymous a‚ribute-based broadcast encryption scheme. In this paper, we first propose an a‚ack on the YRL scheme and showthat the unauthorized receivers can also decrypt the broadcasted message. Next, we propose the Improved-YRL scheme and prove that it achieves anonymity and semantic security under adaptive corruptions in the chosen ciphertext se‚ing. The proof is provided using the dual system encryption technique and is based on three complexity assumptions in composite order bilinear maps. The Improved-YRL scheme is a step forwardin solving the long-standing problem of secure and low overhead anonymous broadcast encryption.

Efficient revocable hierarchical identity-based encryption using cryptographic accumulators

Hierarchical identity-based encryption is an important extension from IBE and has found many applications in the network world. Private key revocation is a crucial requirement for any public key system. In this paper, we propose a novel revocation method for the hierarchical identity-based encryption. Existing revocable hierarchical identity-based encryption schemes have several disadvantages: the key update size increases logarithmically with the number of users in the system, the public information of key update received by each user is different and always related to the level of the identity hierarchy and the security proof of the revocable scheme is very complex. In our scheme, cryptographic accumulators are used to compress hierarchical levels and revoked users’ information into constant values. So we achieve almost constant size of private key update which is irrelevant with the user number in the system. Because of the compression of hierarchical information we can use simple dual system encryption techniques to prove our scheme to be fully secure under several common assumptions without resorting to complex nested dual system encryption techniques.

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.

Efficient privacy preserving predicate encryption with fine-grained searchable capability for Cloud storage

With the fast development in Cloud storage technologies and ever increasing use of Cloud data centres, data privacy and confidentiality has become a must. Indeed, Cloud data centres store each time more sensitive data such as personal data, organizational and enterprise data, transactional data, etc. However, achieving confidentiality with flexible searchable capability is a challenging issue. In this article, we show how to construct an efficient predicate encryption with fine-grained searchable capability. Predicate Encryption (PE) can achieve more sophisticated and flexible functionality compared with traditional public key encryption. We propose an efficient predicate encryption scheme by utilizing the dual system encryption technique, which can also be proved to be IND-AH-CPA (indistinguishable under chosen plain-text attack for attribute-hiding) secure without random oracle. We also carefully analyse the relationship between predicate encryption and searchable encryption. To that end, we introduce a new notion of Public-Key Encryption with Fine-grained Keyword Search (PEFKS). Our results show that an IND-AH-CPA secure PE scheme can be used to construct an IND-PEFKS-CPA (indistinguishable under chosen plain-text attack for public-key encryption with fine-grained keyword search) secure PEFKS scheme. A new transformation of PE-to-PEFKS is also proposed and used to construct an efficient PEFKS scheme based on the transformation from the proposed PE scheme. Finally, we design a new framework for supporting privacy preserving predicate encryption with fine-grained searchable capability for Cloud storage. Compared to most prominent frameworks, our framework satisfies more features altogether and can serve as a basis for developing such frameworks for Cloud data centres.

Adaptively Attribute-Hiding (Hierarchical) Inner Product Encryption

This paper proposes the first inner product encryption (IPE) scheme that is adaptively secure and fully attribute-hiding (attribute-hiding in the sense of the definition by Katz, Sahai and Waters), while the existing IPE schemes are either fully attribute-hiding but selectively secure or adaptively secure but weakly attribute-hiding. The proposed IPE scheme is proven to be adaptively secure and fully attribute-hiding under the decisional linear assumption in the standard model. The IPE scheme is comparably as efficient as the existing attribute-hiding IPE schemes. We also present a variant of the proposed IPE scheme with the same security that achieves shorter public and secret keys. A hierarchical IPE scheme can be constructed that is also adaptively secure and fully attribute-hiding under the same assumption. In this paper, we extend the dual system encryption technique by Waters into a more general manner, in which new forms of ciphertext and secret keys are employed and new types of information theoretical tricks are introduced along with several forms of computational reduction.

Adaptively secure broadcast encryption under standard assumptions with better efficiency

In this study, the authors present an efficient public-key broadcast encryption (PKBE) scheme with sub-linear size of public keys, private keys and ciphertexts and prove its adaptive security under standard assumptions. Compared with the currently best scheme of Garg et al. (CCS 2010) that provides adaptive security under standard assumptions and sub-linear size of various parameters, the ciphertext size of the author's scheme is 94% shorter and the encryption algorithm of their scheme is also 2.8 times faster than the scheme of Garg et al. To achieve their scheme, they adapt the dual system encryption technique of Waters. However, there is a challenging problem to use this technique for the construction of PKBE with sub-linear size of ciphertexts such as a tag compression problem. To overcome this problem, they first devise a novel tag update technique for broadcast encryption. Using this technique, they build an efficient PKBE scheme in symmetric bilinear groups, and prove its adaptive security under standard assumptions.

Adaptively Secure Identity-Based Broadcast Encryption With a Constant-Sized Ciphertext

In this paper, we present an adaptively secure identity-based broadcast encryption system featuring constant sized ciphertext in the standard model. The size of the public key and the private keys of our system are both linear in the maximum number of receivers. In addition, our system is fully collusion-resistant and has stateless receivers. Compared with the state-of-the-art, our scheme is well optimized for the broadcast encryption. The computational complexity of decryption of our scheme depends only on the number of receivers, not the maximum number of receivers of the system. Technically, we employ dual system encryption technique and our proposal offers adaptive security under the general subgroup decisional assumption. Our scheme demonstrates that the adaptive security of the schemes utilizing a composite order group can be proven under the general subgroup decisional assumption, while many existing systems working in a composite order group are secure under multiple subgroup decision assumptions. We note that this finding is of an independent interest, which may be useful in other scenarios.

Sequential aggregate signatures with short public keys without random oracles

The notion of aggregate signature has been motivated by applications and it enables any user to compress different signatures signed by different signers on different messages into a short signature. Sequential aggregate signature, in turn, is a special kind of aggregate signature that only allows a signer to add his signature into an aggregate signature in sequential order. This latter scheme has applications in diversified settings such as in reducing bandwidth of certificate chains and in secure routing protocols. Lu, Ostrovsky, Sahai, Shacham, and Waters (EUROCRYPT 2006) presented the first sequential aggregate signature scheme in the standard model. The size of their public key, however, is quite large (i.e., the number of group elements is proportional to the security parameter), and therefore, they suggested as an open problem the construction of such a scheme with short keys.In this paper, we propose the first sequential aggregate signature schemes with short public keys (i.e., a constant number of group elements) in prime order (asymmetric) bilinear groups that are secure under static assumptions in the standard model. Furthermore, our schemes employ a constant number of pairing operations per message signing and message verification operation. Technically, we start with a public-key signature scheme based on the recent dual system encryption technique of Lewko and Waters (TCC 2010). This technique cannot directly provide an aggregate signature scheme since, as we observed, additional elements should be published in a public key to support aggregation. Thus, our constructions are careful augmentation techniques for the dual system technique to allow it to support sequential aggregate signature schemes. We also propose a multi-signature scheme with short public parameters 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.

New constructions of dynamic threshold cryptosystem

This study deals with the dynamic property of threshold cryptosystem. A dynamic threshold cryptosystem allows the sender to choose the authorized decryption group and the threshold value for each message dynamically. We first introduce an identity based dynamic threshold cryptosystem, and then use the Canetti-Halevi-Katz (CHK) transformation to transform it into a fully secure system in the traditional public key setting. Finally, the elegant dual system encryption technique is applied to constructing a fully secure dynamic threshold cryptosystem with adaptive security.

Fully secure revocable attribute-based encryption

Distributed information systems require complex access control which depends upon attributes of protected data and access policies. Traditionally, to enforce the access control, a file server is used to store all data and act as a reference to check the user. Apparently, the drawback of this system is that the security is based on the file server and the data are stored in plaintext. Attribute-based encryption (ABE) is introduced first by Sahai and Waters and can enable an access control mechanism over encrypted data by specifying the users’ attributes. According to this mechanism, even though the file server is compromised, we can still keep the security of the data. Besides the access control, user may be deprived of the ability in some situation, for example paying TV. More previous ABE constructions are proven secure in the selective model of security that attacker must announce the target he intends to attack before seeing the public parameters. And few of previous ABE constructions realize revocation of the users’ key. This paper presents an ABE scheme that supports revocation and has full security in adaptive model. We adapt the dual system encryption technique recently introduced by Waters to ABE to realize full security.