SCAR: Security Compliance Analysis and Resynthesis of Reconfigurable Scan Networks

Reconfigurable scan networks (RSNs) enable an efficient reliability management throughout the device lifetime. They can be used for controlling integrated instruments, such as aging monitors or built-in self-test (BIST) registers, as well as for collecting the evaluation results from them. At the same time, they may impose a security threat, since the additional connectivities introduced by the RSN can possibly be misused as a side channel. This article presents an approach for security compliance analysis and resynthesis (SCAR) of RSNs to integrate an RSN compliant with the security properties of the initial design. First, the reachability properties of the original design are accurately computed. The connectivities inside the RSN, which exceed the allowed connectivity of the initial design, are identified using the presented security compliance analysis. Next, all violations are resolved by automated Resynthesis with a minimized number of structural changes. As a result of SCAR, any information leakage due to the RSN integration is prevented, while the accessibility of the instruments through the RSN is preserved. The approach is able to analyze complex control dependencies and obtains a compliant RSN even for the largest available benchmarks.