Secure Test with RSNs: Seamless Authenticated Extended Confidentiality

The testability of electronic devices is of critical importance and it is often supported by IEEE standards. The presence of test structures, on the other hand, paves the way for malicious attackers to access the circuit and extract confidential knowledge such as secret keys or intellectual property. Removing the access to these structures after manufacturing test may prevent security breaches, but this solution is not definitive and excludes the possibility of advanced uses such as online debugging, diagnosis of designs and on-line updates or monitoring. For this reason, it is important to maintain the test infrastructure but to protect it against threats either external (e.g., attackers) or internal (e.g., hardware trojans). This can be achieved through protocols ensuring authentication added to confidentiality capabilities. In the case of Reconfigurable Scan Networks (RSN - IEEE 1687), some solutions currently exist, but are limited to external threats. In this paper, we review the recent state of the art in the domain, and present a novel solution addressing in a comprehensive and low-cost manner authentication and confidentiality, both inside and outside the device.