Tassos Dimitriou’s research while affiliated with Kuwait University and other places

The extended Berkeley Packet Filter (eBPF) is a lightweight and fast 64-bit RISC-like virtual machine (VM) inside the Linux kernel. eBPF has emerged as the most promising and de facto standard of executing untrusted, user-defined specialized code at run-time inside the kernel with strong performance, portability, flexibility, and safety guarantees. Due to these key benefits and availability of a rich ecosystem of compilers and tools within the Linux kernel, eBPF has received widespread adoption by both industry and academia for a wide range of application domains which include enhancing performance of monitoring tools, providing a variety of new security mechanisms, data collection tools and data screening applications. In this review, we investigate the landscape of existing eBPF use-cases and trends with aim to provide a clear roadmap for researchers and developers. We first introduce the necessary background knowledge for eBPF before delving into its applications. Although, the potential use-cases of eBPF are vast, we restrict our focus on four key application domains related to networking, security, storage, and sandboxing. Then for each application domain, we analyze and summarize solution techniques along with their working principles in an effort to provide an insightful discussion that will enable researchers and practitioners to easily adopt eBPF into their designs. Finally, we delineate several exciting research avenues to fully exploit the revolutionary eBPF technology.

In this work we develop a rewarding framework that can be used to enhance existing crowd-sensing applications. Although a core requirement of such systems is user engagement, people may be reluctant to participate as sensitive information about them may be leaked or inferred from submitted data. The use of monetary rewards can help incentivize participation, thereby increasing not only the amount but also the quality of sensed data. Our framework allows users to submit data and obtain Bitcoin payments in a privacy-preserving manner, preventing curious providers from linking the data or the payments back to the user. At the same time, it prevents malicious user behavior such as double-redeeming attempts, where a user tries to obtain rewards for multiple submissions of the same data. More importantly, it ensures the fairness of the exchange in a completely trustless manner; by relying on the Blockchain, the trust placed on third parties in traditional fair exchange protocols is eliminated. Finally, our system is highly efficient as most of the protocol steps do not utilize the Blockchain network. When they do, only the simplest of Blockchain transactions are used as opposed to prior works that are based on the use of more complex smart contracts.

Certified mail is a special postal service that provides the sender with a proof that the mail was successfully received by the other party. However, when it comes to certified electronic mail (CEM), there has not been a widely accepted protocol yet. Most of the existing solutions rely on a Trusted Third Party (TTP) in order to achieve fairness, which can become a bottleneck and lead to more charges and computations. Other solutions that do not rely on a TTP require a high computational and communication cost. Blockchains have allowed the creation of TTP-free protocols for fair exchange; however, the existing Blockchain-based protocols are either too expensive or do not meet the necessary fairness and confidentiality guarantees. In this work, we developed two TTP-free Blockchain-based protocols for certified electronic mail that achieve the required security properties of strong fairness, non-repudiation, timeliness, and confidentiality. The first protocol uses simple bitcoin transactions for a single receiver, whereas the second one implements smart contracts for one or multiple receivers. We have analyzed and compared both protocols to existing TTP-free Blockchain solutions and have demonstrated their superior properties and cost. Furthermore, we have implemented the two protocols in a realistic testbed, demonstrating the viability of our approach.

In this work we present DPTS, a data payment and transfer scheme that uses bitcoin payments to reward users for detailed electricity measurements they submit to a utility provider. DPTS emphasizes both privacy and fairness of transactions; not only it allows participants to earn bitcoins in a way that cannot be linked to their actions or identities but also ensures that data is delivered if and only if an appropriate payment is received. While DPTS is described in the smart grid setting, the protocol can also be applied in other areas where incentives are used to increase user participation. One such important area is participatory or crowd-sensing, where individuals use their smartphones to report sensed data back to a campaign administrator and obtain a reward for it. DPTS allows users to enjoy the benefits of participation without compromising anonymity. The proposal is coupled with a security analysis showing the privacy-preserving character of the system along with an efficiency analysis demonstrating the feasibility of our approach.