Comparison and performance analysis of dynamic encrypted control approaches

TL;DR

This paper reviews recent methods for encrypted dynamic control, analyzing their stability and performance, and compares their effectiveness through numerical experiments on a benchmark system.

Contribution

It provides a comprehensive review and stability analysis of recent encrypted control approaches, including new insights into their performance and practical applicability.

Findings

Bootstrapping and resets improve stability

Integer reformulations reduce noise accumulation

FIR controllers offer efficient encrypted control

Abstract

Encrypted controllers using homomorphic encryption have proven to guarantee the privacy of measurement and control signals, as well as system and controller parameters, while regulating the system as intended. However, encrypting dynamic controllers has remained a challenge due to growing noise and overflow issues in the encoding. In this paper, we review recent approaches to dynamic encrypted control, such as bootstrapping, periodic resets of the controller state, integer reformulations, and FIR controllers, and equip them with a stability and performance analysis to evaluate their suitability. We complement the analysis with a numerical performance comparison on a benchmark system.