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In multi-tier supply chains, core enterprises must share sensitive data with dynamically changing partners, while simultaneously ensuring long-term confidentiality and fine-grained access control. However, existing ciphertext-policy attribute-based proxy re-encryption (CP-ABPRE) schemes are not key exposure resilient: once a decryption key is leaked, adversaries may decrypt large volumes of historical ciphertexts, and globally updating keys is prohibitively expensive. To enable key exposure resilient supply chain data sharing, we propose a lattice-based puncturable and revocable CP-ABPRE scheme, termed PR-CP-ABPRE, which incorporates a dual revocation mechanism based on user revocation and tag puncturing. The proxy can transform ciphertexts across different access policies without learning the embedded plaintext. Meanwhile, the data owner can centrally revoke misbehaving or expired receivers via a revocation list, and each receiver can locally puncture its secret key for specific tags, permanently disabling decryption of the corresponding historical ciphertexts while preserving access to other authorized data. Consequently, previously shared supply chain data remain confidential even if secret keys are compromised at a later time. We formalize the security model of PR-CP-ABPRE and prove its security in the standard model. As far as we are aware, PR-CP-ABPRE is the first CP-ABPRE scheme to simultaneously achieve post-quantum security, forward security, and user revocation, thereby establishing a theoretical foundation for post-quantum access control in supply chain environments.

The advent of blockchain technology has ushered a paradigm shift in storage of healthcare data from conventional to online mode. As public ledgers, blockchain platforms provide verifiability of data by all nodes on blockchain. This in turn requires the transactions to be visible to all by default which results in privacy concerns for medical data as they contain sensitive and person-identifiable information that should not be disclosed to everyone. As a result, an access control mechanism is required to maintain regulatory controls over the release and access of medical information to certain entities on blockchain. In this work, we address this issue by proposing a two-level access control technique. We incorporate Ciphertext Policy Attribute-based encryption to provide authorization privileges for various parties involved. After that, Proxy Re-encryption is used to attain secure data transfer and anonymity to the requester only. The data owner is not required to provide the requester with the decryption key and decryption will still be done successfully. This property has not been achieved in previous works. The proposed framework’s security is thoroughly examined. The widely established Burrows–Abadi–Needham (BAN) logic is employed to demonstrate the correctness of the proposed framework’s functionality. We show that our framework provides many new security features compared to its peer proposed models. We use the OMNET++ software to simulate our proposed framework and analyze its storage and computation costs in order to determine its efficiency.

Population aging is currently a tough problem of many countries. How to utilize modern technologies (including both information and medical technologies) to improve the service quality of health information is an important issue. Personal Health Record (PHR) could be regarded as a kind of health information records of individuals. A ciphertext policy attribute-based encryption (CP-ABE) is a cryptographic primitive for fine-grained access control of outsourced data in clouds. In order to enable patients to effectively store his medical records and PHR data in medical clouds, we propose an improved multi-user CP-ABE scheme with the functionality of keyword search which enables data users to seek for specific ciphertext in the cloud server by using a specific keyword. Additionally, we adopt an independent proxy server in the proposed system architecture to isolate the communication between clients and the cloud server, so as to prevent cloud servers from suffering direct attacks and also reduce the computational loading of cloud servers. Compared with the previous approach, the proposed encryption algorithm takes less running time and the ciphertext length is also relatively short. Moreover, the procedures of re-encryption and pre-decryption only require one exponentiation computation, respectively.

Abstract This paper proposes an efficient and secure means for power-constrained Internet of Things (IoT) devices to delegate computationally intensive tasks to proxy servers or nodes in decentralized systems. While such architectures offer advantages in terms of access to computing power and storage, they also raise significant data privacy and security concerns. The proposed solution, a novel residual number system-based all-or-nothing transform (R-AONT) scheme, leverages the parallel processing capabilities of residual number systems to transform input data into residues, which are then encrypted with a symmetric key cipher. The R-AONT scheme first encrypts residues with a symmetric key cipher, producing a ciphertext that is transformed into an R-AONT package using an all-or-nothing transform. This package is distributed across nodes to maintain data privacy and security. The R-AONT scheme is efficient in encoding various sizes of text and image data, with a throughput of 21.19 KB/s when encrypting a 1 KB text file. The scheme reduces a 4 KB input to 0.75 KB for CP-ABE encryption, which demonstrates a significant compression ratio. Although the R-AONT scheme provides high levels of security and privacy, it has a trade-off in terms of storage overhead. The conversion of input data into residues adds additional bits to the data, increasing storage requirements. However, this storage overhead is considered acceptable, given the increased security and efficiency provided by the scheme. The R-AONT scheme demonstrates potential applications in IoT devices and decentralized systems, enabling power-constrained devices to securely delegate computationally intensive tasks to more capable proxy nodes

Ciphertext-Policy Attribute-Based Encryption (CP-ABE) is suitable for data access control on a cloud storage system. In CP-ABE, the data owner encrypts data under the access structure over attributes and a set of attributes assigned to users is embedded in user’s secret key. A user is able to decrypt if his attributes satisfy the ciphertext’s access structure. In CP-ABE, processes of user’s attribute revocation and grant are concentrated on the authority and the data owner. In this paper, we propose a ciphertext-policy attribute-based encryption scheme delegating attribute revocation processes to Cloud Server by proxy re-encryption. The proposed scheme does not require generations of new secret key when granting attributes to a user and supports any Linear Secret Sharing Schemes (LSSS) access structure. We prove that the proposed scheme is secure against attack by unauthorized users and Cloud Server.