Revocable Attribute-based Encryption Scheme Research Articles

Revocable-Attribute-Based Encryption with En-DKER from Lattices

Cloud computing offers abundant computing resources and scalable storage, but data leakage in the cloud storage environment is a common and critical concern due to inadequate protection measures. Revocable-attribute-based encryption (RABE) is introduced as an advanced form of identity-based encryption (IBE), which encrypts sensitive data while providing fine-grained access control and an effective user revocation mechanism. However, most existing RABE schemes are not resistant to quantum attacks and are limited in their application scenarios due to the revocation model. In this paper, we propose a RABE scheme constructed from lattices. Our scheme has several advantages, including a near-zero periodic workload for the key generation center (KGC), ensuring scalability as the number of users increases. Additionally, the encryptor is relieved from managing a revocation list. Moreover, our scheme guarantees the confidentiality and privacy of other ciphertexts even if the decryption key for a specific period is compromised. We validated the correctness of our scheme and demonstrated its security under the assumption of learning with errors (LWE), which is widely believed to be resistant to quantum attacks. Finally, we provide an application example of our RABE scheme in the electronic healthcare scenario.

Unbounded and Efficient Revocable Attribute-Based Encryption With Adaptive Security for Cloud-Assisted Internet of Things

Existing attribute-based encryption (ABE) schemes with revocation to secure the cloud-assisted Internet of Things (IoTs) raise challenges, such as eliminating the need for predefined public parameters in system initialization, performing the encryption and decryption operations efficiently, and achieving adaptive security under standard security assumption. In this article, we address these challenges by proposing an unbounded and efficient revocable ABE scheme with adaptive security for cloud-assisted IoTs. Distinct from the previous approaches in this field, our scheme not only efficiently realizes access control over encrypted data in a fine-grained and revocable way but also is proved to be adaptively secure under standard decision linear assumption. Meanwhile, the parameters do not need to be predefined in the system initialization and thus, our scheme satisfies the unbounded property. Moreover, the monotonic span program (MSP) is elegantly utilized as the access structure to reduce the number of bilinear pairing and exponentiation operations for encryption and decryption. Theoretical performance analysis and experiment evaluation disclose that our proposed scheme owns outstanding feasibility, efficiency, and effectiveness.

Lattice‐based revocable attribute‐based encryption with decryption key exposure resistance

Attribute-based encryption (ABE) is a promising management method that enables fine-grained access control in large-scale systems. Revocable ABE (RABE) can support a key revocation mechanism in an ABE system. With the advent of the Internet of Things, users may need to delegate their decryption capacity to other devices, which requires that RABE meet a necessary feature called decryption key exposure resistance (DKER). Although many constructions about RABE from bilinear maps have been proposed, the situation of lattice-based constructions with DKER is less satisfactory. In order to narrow this gap, this paper propose the first lattice-based RABE with DKER. First, a formal description of RABE with DKER and the corresponding security models is proposed. Subsequently, a lattice-based RABE scheme without DKER is constructed and it is proved to be selective indistinguishability under chosen-plaintext attack (IND-CPA) security based on Learning with Errors (LWE). To achieve DKER, this paper construct a RABE scheme by using the RABE scheme without DKER and a key extension mechanism as its building blocks. Finally, this paper show that this scheme is selective IND-CPA security, with the DKER based on LWE.

Indirect Revocable KP-ABE With Revocation Undoing Resistance

Lately, many cloud-based applications proposed attribute-based encryption (ABE) as an all-in-one solution for achieving confidentiality and access control. Within this paradigm, data producers store the encrypted data on a semi-trusted cloud server, and users, holding decryption keys issued by a key authority, can decrypt data according to some access control policy. To be used in practical cases, any ABE scheme should implement a key revocation mechanism which assures that a compromised decryption key cannot be used anymore to decrypt data. Yu <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">et al.</i> (2010) introduced an ABE scheme with revocation capabilities that enjoys several unique advantages, such as reactivity and efficiency. In the scheme, the cloud server is entitled to update keys and ciphertexts in order to achieve revocation. Unfortunately, the cloud server retains the power to undo the revocation of a key (revocation undoing attack) so endangering confidentiality. In this article, we propose a revocable ABE scheme that still ensures the advantages of Yu <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">et al.</i> ’s scheme, but it also resists to the revocation undoing attack. We formally prove the security of our scheme and show through simulations that the user experiences a slightly higher computational cost with respect to Yu <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">et al.</i> ’s scheme.

Dynamic fine-grained access control scheme for vehicular ad hoc networks

Secure communication in vehicular ad hoc networks (VANETs) has been extensively researched; however, access control in VANETs has not been studied adequately. Access control ensures that only authorized vehicles receive quality services over the VANETs to enhance the driving experience. Attribute-based encryption (ABE) with revocation is a promising access control technique that keeps data confidential and is suitable for application in VANETs. However, most existing revocable ABE schemes require the private keys of all non-revoked users to be updated if the private key of any user is revoked, which makes the implementation of such schemes extremely inefficient. In this paper, a dynamic fine-grained access control scheme based on ABE is proposed to ensure vehicle network security. It enables the message sender to determine which vehicles receive the message according to their attributes and can also freely revoke the decryption authorization of certain vehicles without needing to update all non-revoked keys. To the best of our knowledge, this is the first time that secure and efficient dynamic access control in VANETs has been achieved. Performance analysis and simulation evaluations have shown that the algorithm is more efficient in terms of computational delay and communication overhead, as compared with existing schemes.

(Dual) server-aided revocable attribute-based encryption with decryption key exposure resistance

Attribute-based encryption (ABE) is a promising approach that enables scalable access control on encrypted data. However, one of the main efficiency drawbacks of ABE is the lack of practical user revocation mechanisms. In ESORICS 2016, Cui et al. proposed the first cloud server-aided revocable ABE scheme to achieve efficient user revocation. However, the cloud server cannot be fully compromised by an adversary. Otherwise, it will suffer from local decryption key exposure (DKE) attacks. In this paper, we first revisit Cui et al. security model, and enhance it by capturing the DKE attacks on user’s local decryption keys and meanwhile allowing the adversary to fully corrupt the cloud server. We then construct a server-aided revocable ABE based on Rouselakis–Waters ciphertext-policy ABE (CCS 2013). It was showed that our scheme is secure in the new security model and maintains the outstanding properties of efficient user revocation, short local ciphertext size and fast local decryption. Further, we propose a dual framework for server-aided revocable ABE, in which the update keys are distributed to local users rather than the cloud server. With the exception of interaction with the KGC, the local user still has the same efficiency as that of first scheme.

Efficient Ciphertext-Policy Attribute-Based Online/Offline Encryption with User Revocation

Attribute-Based Encryption (ABE) must provide an efficient revocation mechanism since a user’s private key can be compromised or expired over time. The existing revocable ABE schemes have the drawbacks of heavy computational costs on key updates and encryption operations, which make the entities for performing these operations a possible bottleneck in practice applications. In this paper, we propose an efficient Ciphertext-Policy Attribute-Based Online/Offline Encryption with user Revocation (R-CP-ABOOE). We integrate the subset difference method with ciphertext-policy ABE to significantly improve key-update efficiency on the side of the trusted party from O(rlog⁡(N/r)) to O(r), where N is the number of users and r is the number of revoked users. To reduce the encryption burden for mobile devices, we use the online/offline technology to shift the majority of encryption work to the offline phase, and then mobile devices only need to execute a few simple computations to create a ciphertext. In addition, we exploit a novel trick to prove its selective security under the q-type assumption. Performance analysis shows that our scheme greatly improves the key-update efficiency for the trusted party and the encryption efficiency for mobile devices.

Ciphertext Outdate Attacks on the Revocable Attribute-Based Encryption Scheme With Time Encodings

Cloud storage is a new computing paradigm that allows users to store their data in the cloud and access them anytime anywhere through the Internet. To address the various security issues that may arise in the cloud storage accessed by a large number of users, cryptographic encryption should be considered. Currently, researches on revocable attribute-based encryption (RABE) systems, which provide user revocation function and ciphertext update function by extending attribute-based encryption (ABE) systems that provide access control to ciphertexts, are actively being studied. Recently, Xu et al. proposed a new RABE scheme that combines ABE and identity-based encryption (IBE) schemes to efficiently handle ciphertext update and user revocation functionality. In this paper, we show that there is a serious security problem in Xu et al.’s RABE scheme such that a cloud server can obtain the plaintext information of stored ciphertexts by gathering invalidated credentials of revoked users. Additionally, we also show that the RABE scheme of Xu et al. can be secure in a weaker security model where the cloud server cannot obtain any invalidated credentials of revoked users.

Generic Constructions for Fully Secure Revocable Attribute-Based Encryption

Attribute-based encryption (ABE) is a cryptographic primitive that realizes fine-grained access control. Due to its attractive functionality, several systems based on ABE have been widely constructed so far. In such cryptographic systems, revocation functionality is indispensable in practice to handle withdrawal of users, secret key exposure, and others. While many ABE schemes with various functionalities have been proposed, only a few of these are revocable ABE (RABE). In this paper, we propose two generic constructions of RABE from ABE. Our first construction employs the pair encoding framework (Attrapadung, EUROCRYPT 2014), and combines identity-based revocation and ABE via the generic conjunctive conversion of Attrapadung and Yamada (CT-RSA 2015). Our second construction directly converts ABE to RABE when ABE supports Boolean formulae. Since our constructions preserve functionalities of the underlying ABE, we can instantiate various fully secure RABE schemes for the first time, e.g., supporting regular languages, with unbounded attribute size and policy structure, and with constant-size ciphertext and secret key.

Secure, Efficient and Fine-Grained Data Access Control Mechanism for P2P Storage Cloud

By combining cloud computing and Peer-to-Peer computing, a P2P storage cloud can be formed to offer highly available storage services, lowering the economic cost by exploiting the storage space of participating users. However, since cloud severs and users are usually outside the trusted domain of data owners, P2P storage cloud brings forth new challenges for data security and access control when data owners store sensitive data for sharing in the trusted domain. Moreover, there are no mechanisms for access control in P2P storage cloud. To address this issue, we design a ciphertext-policy attribute-based encryption (ABE) scheme and a proxy re-encryption scheme. Based on them, we further propose a secure, efficient and fine-grained data Access Control mechanism for P2P storage Cloud named ACPC. We enforce access policies based on user attributes, and integrate P2P reputation system in ACPC. ACPC enables data owners to delegate most of the laborious user revocation tasks to cloud servers and reputable system peers. Our security analysis demonstrates that ACPC is provably secure. The performance evaluation shows that ACPC is highly efficient under practical settings, and it significantly reduces the computation overheads brought to data owners and cloud servers during user revocation, compared with other state-of-the-art revocable ABE schemes.

Fine-grained user access control in ciphertext-policy attribute-based encryption

Key revocation is one of the most challenging and open issues in attribute-based encryption (ABE). The previous revocable ABE schemes feature a mechanism that revokes the attribute key periodically without any consideration of the user membership associated with the attribute. Thus, non-revoked users are enforced to access the key authority periodically to receive keying materials in order to update the current key. This is due to the fact that the revocation is done only on the attribute level, which results in security and scalability problems. In this paper, we propose a fine-grained user revocation scheme without affecting any non-revoked users who share the same attributes in ciphertext-policy ABE; it does not require the users to access the key authority and to update keys periodically. The proposed scheme improves the efficiency compared with previous revocable schemes and enhances the security in terms of the backward/forward secrecy on any membership changes in the ciphertext-policy ABE system. Copyright © 2011 John Wiley & Sons, Ltd.