Secure Mutual Testing Strategy for Cryptographic SoCs

This article presents a secure mutual testing strategy for System-on-Chips (SoCs) that implement cryptographic functionalities. Such approach eliminates the need for an additional trusted component that is used to test security sensitive cores in a SoC, like symmetric and public-key cryptographic modules. We combine two test approaches: Logic Built In Self Test (BIST) and secure scan-chain based testing and develop a strategy that preserves the test quality of the standard test methods, enhancing security of the testing scheme. In order to minimize the area overhead of the presented solution, we re-use the existing modules in different manners: a public-key cryptographic core to build the BIST infrastructure and a symmetric one to authenticate a device under test to a test server, thus preventing an unauthorized user from accessing the test interface. By doing so, we achieve both testability and security at the minimal cost.