On the Necessity, Security Requirements and Performance Requirements of Digital Signature Co-processors in Li-ion BMSs

Modern lithium-ion (Li-ion) batteries integrate microcontrollers and dedicated resources for monitoring and control distributed in different physical layers. The overall system is called Battery Management System (BMS) and aims to estimate, for instance, the state of charge and the state of health maximizing the life and reliability of batteries. Anyway, BMSs can be threatened by security issues and attacks. Counterfeiting of components and data manipulation can alter the functionalities of the BMS, causing several consequences, such as the explosion of batteries due to the overcharge. In recent work, we proposed a novel and robust security approach for the integrity and authentication of BMS data and anti-counterfeiting mechanisms. In addition, it can be used to improve the performance (by hardware acceleration) and the security level (with advanced features such as secure storage and isolation of security-critical assets) of other solutions proposed in the literature, which otherwise might be compromised. For this purpose, the integration of a co-processor for the digital signature on elliptic curves (ECDSA) becomes fundamental. In this work, we demonstrate the necessity of integrating such a cryptographic co-processor, and we define its requirements in terms of both security and performance. Moreover, we confirm and extend the analysis related to the scaling of the characteristics (resources, frequency, latency) of ECDSA modules according to the internal data path. To the best of our knowledge, this is the first work in the literature addressing this topic for Li-ion BMS.