  Secure sensor calibration constitutes a foundational step that underpins
operational safety in the Industrial Internet of Things. While much attention
has been given to IoT security such as the use of TLS to secure sensed data,
little thought has been given to securing the calibration infrastructure
itself. Currently traceability is achieved via manual verification using
paper-based datasheets which is both time consuming and insecure. For instance,
when the calibration status of parent devices is revoked as mistakes or
mischance is detected, calibrated devices are not updated until the next
calibration cycle, leaving much of the calibration parameters invalid. Aside
from error, any party within the calibration infrastructure can maliciously
introduce errors since the current paper based system lacks authentication as
well as non-repudiation. In this paper, we propose a novel resilient
architecture for calibration infrastructure, where the calibration status of
sensor elements can be verified on-the-fly to the root of trust preserving the
properties of authentication and non-repudiation. We propose an implementation
based on smart contracts on the Ethereum network. Our evaluation shows that
Ethereum is likely to address the protection requirements of traceable
measurements.
