https://hdl.handle.net/20.500.12761/1 2026-05-08T12:06:59Z 2026-05-08T12:06:59Z Gentile, Vincenzo Giustiniano, Domenico Frómeta Fonseca, Dayrene https://hdl.handle.net/20.500.12761/2033 2026-05-05T00:00:14Z 2026-06-16T00:00:00Z

Soil Moisture Sensing through Phase Measurements in Analog Backscatter Systems Gentile, Vincenzo; Giustiniano, Domenico; Frómeta Fonseca, Dayrene Conventional low-cost soil moisture sensors consume milliwatts of power, limiting their scalability for battery free agricultural IoT. To bridge this gap, we propose a narrow band phase-difference approach for soil moisture estimation using ultra-low-power analog backscatter at 868MHz. We develop a geometric electromagnetic model relating spatial phase shifts to soil permittivity, proving differential phase remains a valid observable despite refraction across the layered soil–air interface. We further characterize non-ideal hardware effects, establishing how antenna impedance mismatches and other impairments introduce systematic phase biases that require calibration. Our experiments demonstrate reliable discrimination between dry and wet soils, validating a battery-free sensing architecture that offers a scalable solution for sustainable water management.

2026-06-16T00:00:00Z Attiya, Hagit Fernández Anta, Antonio Milani, Alessia Rapetti, Alexandre Travers, Corentin https://hdl.handle.net/20.500.12761/2032 2026-05-01T00:00:18Z 2025-10-01T00:00:00Z

Auditable Shared Objects: From Registers to Synchronization Primitives Attiya, Hagit; Fernández Anta, Antonio; Milani, Alessia; Rapetti, Alexandre; Travers, Corentin Auditability allows to track operations performed on a shared object, recording who accessed which information. This gives data owners more control on their data. Initially studied in the context of single-writer registers, this work extends the notion of auditability to other shared objects, and studies their properties. We start by moving from single-writer to multi-writer registers, and provide an implementation of an auditable n-writer m-reader read / write register, with O(n+m) step complexity. This implementation uses (m+n)-sliding registers, which have consensus number m+n. We show that this consensus number is necessary. The implementation extends naturally to support an auditable load-linked / store-conditional (LL/SC) shared object. LL/SC is a primitive that supports efficient implementation of many shared objects. Finally, we relate auditable registers to other access control objects, by implementing an anti-flickering deny list from auditable registers.

2025-10-01T00:00:00Z Attiya, Hagit Fernández Anta, Antonio Milani, Alessia Rapetti, Alexandre Travers, Corentin https://hdl.handle.net/20.500.12761/2031 2026-05-01T00:00:14Z 2025-06-01T00:00:00Z

Auditing without Leaks Despite Curiosity Attiya, Hagit; Fernández Anta, Antonio; Milani, Alessia; Rapetti, Alexandre; Travers, Corentin Auditing data accesses helps preserve privacy and ensures accountability by allowing one to determine who accessed (potentially sensitive) information. A prior formal definition of register auditability was based on the values returned by read operations, without accounting for cases where a reader might learn a value without explicitly reading it or gain knowledge of data access without being an auditor. This paper introduces a refined definition of auditability that focuses on when a read operation is effective, rather than relying on its completion and return of a value. Furthermore, we formally specify the constraints that prevent readers from learning values they did not explicitly read or from auditing other readers' accesses. Our primary algorithmic contribution is a wait-free implementation of a multi-writer, multi-reader register that tracks effective reads while preventing unauthorized audits. The key challenge is ensuring that a read is auditable as soon as it becomes effective, which we achieve by combining value access and access logging into a single atomic operation. Another challenge is recording accesses without exposing them to readers, which we address using a simple encryption technique (one-time pad). We extend this implementation to an auditable max register that tracks the largest value ever written. The implementation deals with the additional challenge posed by the max register semantics, which allows readers to learn prior values without reading them. The max register, in turn, serves as the foundation for implementing an auditable snapshot object and, more generally, versioned types. These extensions maintain the strengthened notion of auditability, appropriately adapted from multi-writer, multi-reader registers.

2025-06-01T00:00:00Z Albouy, Timothé Fernández Anta, Antonio Georgiou, Chryssis Nicolaou, Nicolas Wang, Junlang https://hdl.handle.net/20.500.12761/2030 2026-05-01T00:00:13Z 2025-12-01T00:00:00Z

Tight Conditions for Binary-Output Tasks Under Crashes Albouy, Timothé; Fernández Anta, Antonio; Georgiou, Chryssis; Nicolaou, Nicolas; Wang, Junlang This paper explores necessary and sufficient system conditions to solve distributed tasks with binary outputs (i.e., tasks with output values in {0,1}). We focus on the distinct output sets of values a task can produce (intentionally disregarding validity and value multiplicity), considering that some processes may output no value. In a distributed system with n processes, of which up to t ≤ n can crash, we provide a complete characterization of the tight conditions on n and t under which every class of tasks with binary outputs is solvable, for both synchronous and asynchronous systems. This output-set approach yields highly general results: it unifies multiple distributed computing problems, such as binary consensus and symmetry breaking, and it produces impossibility proofs that hold for stronger task formulations, including those that consider validity, account for value multiplicity, or move beyond binary outputs.

2025-12-01T00:00:00Z