The widespread adoption of cloud computing and the exponential growth of data highlight the need for secure data sharing and querying. Attribute-based keyword search (ABKS) has emerged as an efficient means of searching encrypted data stored in the cloud. However, existing ABKS schemes incur high end-to-end delay and are vulnerable to quantum computer attacks and/or (insider) keyword guessing attacks (KGA). To address these vulnerabilities, this paper introduces a new concept called attribute-based authenticated encryption with keyword search (ABAEKS) and proposes an efficient ABAEKS scheme. Our ABAEKS has low end-to-end delay, and is resistant to both quantum computer attacks and (insider) KGA. In addition, we formalize the security model of ABAEKS system and prove its security in the random oracle model. Finally, we conduct a comprehensive performance evaluation of ABAEKS, and the experimental results show that our ABAEKS is computationally efficient and outperforms current state-of-the-art ABKS schemes.

Fine-grained access control systems facilitate granting differential access rights to a set of users and allow flexibility in specifying the access rights of individual users. As an important fine-grained access control technique, key-policy attribute-based encryption (KP-ABE) has been introduced to achieve fine-grained access control over encrypted data, where each ciphertext is associated with an attribute set such that users satisfying the attribute set can decrypt the ciphertext. In the real-world application scenarios of KP-ABE, various situations such as users leaving the system, compromise of users’ private keys, and business requirements frequently occur, necessitating the revocation of decryption rights for large-scale users. To address the user revocation, numerous revocable KP-ABE schemes have been proposed. However, existing revocable KP-ABE schemes are vulnerable to quantum computer attacks. More importantly, existing solutions fail to address the user addition, where users capable of decrypting certain ciphertexts would like to grant decryption rights to others; this is a highly common requirement, such as changes in user decryption permissions and business needs. This paper explores a potentially new avenue of research to address the above issues by introducing a novel cryptographic primitive called key-policy ABE with switchable attributes (KP-ABE-SA). In the KP-ABE-SA system, each ciphertext linked to an attribute set can be transformed into one associated with another (distinct) attribute set, enabling both user revocation and addition. Furthermore, to withstand quantum computer attacks, we construct a KP-ABE-SA scheme based on the Learning with Errors (LWE) assumption, which is widely believed to be quantum-resistant. Finally, we conduct a comprehensive performance evaluation of our LWE-based KP-ABE-SA scheme, and the experimental results show that the proposed LWE-based KP-ABE-SA scheme is efficient and practical.

Proxy re-encryption (PRE), as a promising cryptographic primitive for secure data sharing in clouds, has been widely studied for decades. PRE allows the proxies to use the re-encryption keys to convert ciphertexts computed under the delegator’s public key into ones that can be decrypted using the delegatees’ secret keys, without knowing anything about the underlying plaintext. This delegable property of decryption rights enables flexible cloud data sharing, but it raises an important issue: if some proxies reveal their re-encryption keys, or collude with some delegatees to create a pirate decoder, then anyone who gains access to the pirate decoder can decrypt all ciphertexts computed under the delegator’s public key without the delegator’s permission. This paper opens up a potentially new avenue of research to address the above (re-encryption) key abuse problem by proposing the first public trace-and-revoke PRE system, where the malicious delegatees and proxies involved in the generation of a pirate decoder can be identified by anyone who gains access to the pirate decoder, and their decryption capabilities can subsequently be revoked by the content distributor. Our construction is multi-hop, supports user revocation and public (black-box) traceability, and achieves significant efficiency advantages over previous constructions. Technically, our construction is a generic transformation from inner-product functional PRE (IPFPRE) that we introduce to trace-and-revoke PRE. In addition, we instantiate our generic construction of trace-and-revoke PRE from the Learning with Errors (LWE) assumption, which was widely believed to be quantum-resistant. This is achieved by proposing the first LWE-based IPFPRE scheme, which may be of independent interest. Finally, we conduct a comprehensive performance evaluation of our LWE-based trace-and-revoke PRE scheme, and the experimental results show that the proposed LWE-based trace-and-revoke PRE scheme is practical and outperforms current state-of-the-art traceable PRE schemes.

In the last few decades, ciphertext-policy attribute-based encryption (CP-ABE) technology has attracted great interest, since it can provide fine-grained, flexible, and access control for sensitive data to implement a high secure and efficient data-sharing mechanism. In this article, based on the linear secret sharing scheme (LSSS), an efficient scheme is proposed to realize a collaborative decryption function. For any user group, when the user’s attribute set cannot access the ciphertext alone, the private key of other users in the same group can be used for collaborative decryption with the permission of the data owner. Our scheme uses the LSSS matrix that can significantly reduce the computation and storage overhead when comparing with the existing schemes. Then, a multiauthorization model is created based on the Bohen–Lynn–Shacham technology in order to solve the key-management issue. Finally, we implemented the specific functions of the framework through JAVA, and built a private chain to verify the feasibility of data transfer between users.