IoT based eHealth system brings a revolution to healthcare industry, with which the old healthcare systems can be updated into smarter and more personalized ones. The practitioners can continue monitoring the physical status of the patients at anytime and anywhere, and develop more precise treatment plans by analyzing the collected data, such as heart rate, blood pressure, blood glucose. Actually, these smart sensors used in eHealth system are smart embedded devices (SED). Due to the limitations on hardware capabilities, these inter-connected SEDs lack of security considerations in design and implementation, and face the threats from the network. To prevent the malicious users (or programs) from tampering with the SEDs, trusted platform module (TPM) is adopted, which can guarantee the system integrity via detecting unauthorized modifications to data and system environment. However, due to the limited scalability and insufficient system resources, not all SEDs can be deployed with TPM chips. To address this issue, in this paper, a TPM extension scheme (xTSeH) is proposed. In xTSeH, we have extended the functions of a TPM deployed in a SED (TSED) to those non-TPM-protected SEDs (N-TSED) via network. A shadow TPM in the form of a kernel module is designed as the trust base for the N-TSED, which is the representative of the TPM in TSED. Then, three protocols are proposed to implement the integrity verification and inter-SED authentication. Finally, a Raspberry Pi based prototype system is designed and implemented. The feasibility and usability of our scheme are proved by the analysis of the experimental results of system performance.

As one of the most popular relational databases for embedded devices, SQLite is lightweight to be embedded into applications without installing a specific database management system. However, simplicity and easy-to-use are double-edged swords; while bringing convenience, they also make data processing and storage risky. For example, an attacker can obtain data from a database file or memory and tamper with it once he has gained higher privileges, threatening the database's confidentiality and integrity. To address such security issues, based on a trusted execution environment (TEE) and a trusted platform module (TPM), we have proposed Smaug, a general secure scheme to ensure the confidentiality and integrity of SQLite and similar databases. With Smaug, all the critical data is stored in ciphertext, and data integrity protection is also provided. Besides, with TEE, all the sensitive operations are isolated from the untrusted environment, which can effectively resist attacks against memory. In addition, we use TPM to provide a solid root-of-trust (RoT) for the system. Finally, we have implemented a prototype system, and the performance evaluations have clarified the dominant factors that affect the system availability, providing a reference to the design and implementation of similar systems.

Dynamic Spectrum Sharing (DSS) has been taken as an encouraging method to address the increasing demand for wireless spectrum resources. Without privacy protection in location, however, the primary user will hesitate to share the spectrum with secondary users. In this paper, we present LpriDSS, the first scheme for a spectrum administrator to select spectrum-sharing secondary users while implementing the geo-indistinguishability of primary user. Firstly, we formulate the secondary users selection without privacy in DSS system as an auction problem and demonstrate the location inference attacks based on the winner sets in detail. Then, a ranking metric to characterize the administrators' preference for secondary users is defined. Moreover, a probability of each secondary user being selected as a winner is calculated and used during the process of the secondary user selection. Finally, a truthful payment computation is designed according to that probability. Thorough theoretical analysis and simulation studies show that LpriDSS can simultaneously achieve geo-indistinguishability, approximate social welfare maximization, and truthfulness.

In this paper, we propose BiTDB, a built-in Trusted Execution Environment (TEE) database for embedded systems, to realize higher system availability while ensuring data confidentiality. With BiTDB, dilemmas that the state-of-the-art research work on secure embedded databases has to face can be significantly reduced and eliminated, including (i) complicated research and realization on searchable encryption algorithms (SEA), (ii) limited support to all database operations, and (iii) almost none of specific design and optimizations toward build-in TEE embedded databases. Through BiTDB, all database operations can process plaintext in TEE instead of retrieving ciphertext by developing complicated SEAs. To enable BiTDB to handle database files in Rich Execution Environment (REE) as local ones, we extend the TEE OS with generic file I/O libraries. Then, we contribute three critical optimizations to significantly reduce redundant memory and file operations between TEE and REE, and BiTDB achieve better system performance and availability in embedded systems. Finally, we have implemented the prototype system based on OP-TEE and SQLite for several typical platforms, including virtualization and hardware environments. The TPC-H test shows BiTDB can achieve 85% (on average) of the original database performance while guaranteeing data confidentiality and integrity. Our project repository is at https://github.com/CharlieMCY/BiTDB .

As the foundation of the Web3 trust system, blockchain technology faces increasing demands for scalability. Sharding emerges as a promising solution, but it struggles to handle highly concurrent cross-shard transactions (CSTxs), primarily due to simultaneous ledger operations on the same account. Hyperledger Fabric, a permissioned blockchain, employs multi-version concurrency control for parallel processing. Existing solutions use channels and intermediaries to achieve cross-sharding in Hyperledger Fabric. However, the conflict problem caused by highly concurrent CSTxs has not been adequately resolved. To fill this gap, we propose HiCoCS, a high concurrency cross-shard scheme for permissioned blockchains. HiCoCS creates a unique virtual sub-broker for each CSTx by introducing a composite key structure, enabling conflict-free concurrent transaction processing while reducing resource overhead. The challenge lies in managing large numbers of composite keys and mitigating intermediary privacy risks. HiCoCS utilizes virtual sub-brokers to receive and process CSTxs concurrently while maintaining a transaction pool. Batch processing is employed to merge multiple CSTxs in the pool, improving efficiency. We explore composite key reuse to reduce the number of virtual sub-brokers and lower system overhead. Privacy preservation is enhanced using homomorphic encryption. Evaluations show that HiCoCS improves cross-shard transaction throughput by 3.5-20.2 times compared to the baselines.