  This paper studies provable security guarantees for cyber-physical systems
(CPS) under actuator attacks. In particular, we consider CPS safety and propose
a new attack-detection mechanism based on a zeroing control barrier function
(ZCBF) condition. In addition we design an adaptive recovery mechanism based on
how close the system is from violating safety. We show that the
attack-detection mechanism is sound, i.e., there are no false negatives for
adversarial attacks. Finally, we use a Quadratic Programming (QP) approach for
online recovery (and nominal) control synthesis. We demonstrate the
effectiveness of the proposed method in a simulation case study involving a
quadrotor with an attack on its motors.
