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Modern healthcare has a sharp focus on data aggregation and processing technologies. Consequently, from a data perspective, a patient may be regarded as a timestamped list of medical conditions and their corresponding corrective interventions. Technologies to securely aggregate and access data for individual patients in the quest for precision medicine have led to the adoption of Digital Twins in healthcare. Digital Twins are used in manufacturing and engineering to produce digital models of physical objects that capture the essence of device operation to enable and drive optimization. Thus, a patient's Digital Twin can significantly improve health data sharing. However, creating the Digital Twin from multiple data sources, such as the patient's electronic medical records (EMR) and personal health records (PHR) from wearable devices, presents some risks to the security of the model and the patient. The constituent data for the Digital Twin should be accessible only with permission from relevant entities and thus requires authentication, privacy, and provable provenance. This paper proposes a blockchain-secure patient Digital Twin that relies on smart contracts to automate the updating and communication processes that maintain the Digital Twin. The smart contracts govern the response the Digital Twin provides when queried, based on policies created for each patient. We highlight four research points: access control, interaction, privacy, and security of the Digital Twin and we evaluate the Digital Twin in terms of latency in the network, smart contract execution times, and data storage costs. [ABSTRACT FROM AUTHOR]

The emerging cloud storage technology has significantly improved efficiency and productivity in the traditional electronic healthcare field. However, it has also brought about many security concerns. Ciphertext policy attribute-based encryption (CP-ABE) holds immense potential in achieving fine-grained access control, providing robust security for electronic healthcare data in the cloud. However, current CP-ABE schemes still face issues such as inflexible attribute revocation, relatively lower computational capabilities, and key management. To address these issues, this paper introduces a revocable and traceable undeniable ciphertext policy attribute-based encryption scheme (MA-RUABE). MA-RUABE not only enables fast and accurate data traceability, effectively preventing malicious user key leakage, but also includes a direct revocation feature, significantly enhancing computational efficiency. Furthermore, the introduction of a multi-permission mechanism resolves the issue of centralization of power caused by single-attribute permissions. Furthermore, a security analysis demonstrates that our system ensures resilience against chosen plaintext attacks. Experimental results demonstrate that MA-RUABE incurs lower computational overhead, effectively enhancing system performance and ensuring data-sharing security in cloud-based electronic healthcare systems. [ABSTRACT FROM AUTHOR]

In application scenarios such as cloud storage, a symmetric algorithm can be used to encrypt massive data. However, using the symmetric operation and keys in encryption and decryption, it is very difficult to realize an efficient access control system. The asymmetric encryption algorithm ciphertext-policy attribute-based encryption (CP-ABE), as a versatile one-to-many encryption algorithm, is considered an ideal access control tool to solve the user's distrust of the service provider of cloud storage. However, in a traditional CP-ABE system, the malicious users may deliberately leak their attribute keys to others or build a decryption black box (DB) to provide illegal decryption services for benefits, while no one can determine their identities. To deal with the problems, especially the problem of tracing the DB builder, CP-ABE schemes with black-box traceability have been proposed in the past few years. But in this paper, we point out that for now, the tracing algorithms in all existing schemes actually work on an impractical assumption. That is, whenever a DB receives a decryption request, it always performs the decryption algorithm honestlycorrectly. We argue that if a DB finds the decryption request comes from the tracing algorithm, it may intentionally output incorrect decryption results to counter the tracing. Thus, we present the structural defect of the tracing algorithm applied to all known traceable CP-ABE schemes. We describe the construction of an alert decryption black box (ADB) that is capable of distinguishing a tracing ciphertext from a normal one. We also show how an ADB frustrates the tracing algorithm, and furthermore, malicious users can even apply an ADB to frame innocent users. [ABSTRACT FROM AUTHOR]

Cloud storage is the ideal solution for outsourcing big data since the cloud can store a large amount of data. Cloud storage, on the other hand, raises additional problems about data duplication, fine-grained access control, and privacy, all of these factors are crucial for cloud large data storage. Data duplication approaches based on encrypted data schemes now available do not provide for fine-grained access control. This paper proposes a secure framework for managing data using rapid asymmetric maximum based dynamic size chunking and fuzzy logic for deduplication. Chunking, fingerprinting, hashing, and writing are the four main process of the proposed method. Initially, chunking is done to split the files into chunks. Rapid Asymmetric Maximum (RAM) based Dynamic Size Chunking (DSC) is used in the proposed method. These chunked files are then fingerprinted using hashing process for ensuring data authentication. Then B-tree indexing approach is used in the proposed method in order to keep the fingerprinted in an organized state. General Type2-Fuzzy logic is using Ant Lion Optimization (ALO) is used for detecting duplicate files in the documents. In the cloud storage platform, only non-duplicate documents are safely kept. The Triple Data Encryption Standard is used to do a security study before outsourcing non-duplicate data to a third-party cloud server. The total computation time of the proposed technique is 0.4 s in the inline phase and 0.04 s in the offline phase, and the deduplication ratio is 95% in the inline phase and 90% in the offline phase. This proposed deduplication approach requires less storage, which reduces memory use and processing time. [ABSTRACT FROM AUTHOR]

In smart wards, data generated by wearables and monitoring devices are periodically transferred to the cloud server for long-term logging and subsequent access. Remote cloud storage inevitably raises security and access control challenges. Encryption can secure data but may severely impact the value generated by sharing data. More importantly, the privacy leakage caused by keyword searches is unacceptable for medical data. The designated-server public-key encryption with keyword search (dPEKS) can realize ciphertext-based search. However, existing dPEKS face an efficiency bottleneck as they only achieve one-to-one data sharing. In addition, cloud-controlled access control creates over-centralized power. In contrast, using blockchain to control who can search has the extra benefit that the blockchain can record access behavior for subsequent tracking. Therefore, this paper proposes a blockchain-assisted dPEKS (BC-dPEKS) scheme, which exploits a permissioned blockchain to perform trapdoor generation on behalf of data users and record data uploading and access for tracing. To the best of our knowledge, this is the first scheme to tightly integrate blockchain to change PEKS primitive to achieve one-to-many search. Formal security models, the corresponding security proofs, and comprehensive performance analysis are presented. [ABSTRACT FROM AUTHOR]

• Fast access revocation is a major challenge in cloud storage service. • The encryption key is embedded into a set of coefficients of a polynomial so-called access polynomial. • The scheme supports fast revocation by means of updating the access polynomial coefficients. • Blockchain is utilized to implement access control as a smart contract between data owner and users. • Attribute-based encryption (ABE) is used in response transactions to impose the access policy to the file as well as preserving user anonymity. This paper presents a novel collaboration scheme for secure cloud file sharing using blockchain and attribute-based encryption(ABE). Blockchain enables us to implement access control as a smart contract between data owner and users. Each data owner creates its own smart contract where in a data user can request to access a specific file by registering a transaction. In response transaction, the data owner sends the required credential to the user thereby enabling her/him to decrypt the intended file on the cloud storage. This scheme is decentralized, fault tolerant and secured against DoS attacks. The cipher-key , which is used for file encryption, is embedded into a set of coefficients of a polynomial so-called access polynomial. It is attached to the encrypted file on the cloud storage as a metadata. The data user can restore the cipher-key by means of the credential receiving in response transaction and access polynomial. The data owner uses ABE scheme in response transaction to impose her/him access policy to the file as well as preserving user anonymity. This scheme supports fast revocation of the user access by means of updating the access polynomial coefficients and without any communication overhead to non-revoked users. Through formal verification, we show that the scheme is secure in terms of secrecy of credential information and authentication of participants. Finally, the evaluation results show that our scheme is scalable with acceptable performance up to 20,000 users. [ABSTRACT FROM AUTHOR]