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In this paper, we assess the security and testability of the state-of-the-art design-for-security (DFS) architectures in the presence of scan-chain locking/obfuscation, a group of solution that has previously proposed to restrict unauthorized access to the scan chain. We discuss the key leakage vulnerability in the recently published prior-art DFS architectures. This leakage relies on the potential glitches in the DFS architecture that could lead the adversary to make a leakage condition in the circuit. Also, we demonstrate that the state-of-the-art DFS architectures impose some substantial architectural drawbacks that moderately affect both test flow and design constraints. We propose a new DFS architecture for building a secure scan chain architecture while addressing the potential of key leakage. The proposed architecture allows the designer to perform the structural test with no limitation, enabling an untrusted foundry to utilize the scan chain for manufacturing fault testing without having a need to access the scan chain. Our proposed solution poses negligible limitation/overhead on the test flow, as well as the design criteria. 

The resource-constrained nature of the Internet of Things (IoT) edges, poses a challenge in designing a secure and high-performance communication for this family of devices. Although side-channel resistant ciphers (either block or stream) could guarantee the security of the communication, the energy intensive nature of these ciphers makes them undesirable for lightweight IoT solutions. In this paper, we introduce ExTru, an encrypted communication protocol based on stream ciphers that adds a configurable switching & toggling network (CSTN) to not only boost the performance of the communication in these devices, it also consumes far less energy than the conventional side-channel resistant ciphers. Although the overall structure of the proposed scheme is leaky against physical attacks, we introduce a dynamic encryption mechanism that removes this vulnerability. We demonstrate how each communicated message in the proposed scheme reduces the level of trust. Accordingly, since a specific number of messages, N, could break the communication and extract the key, by using the dynamic encryption mechanism, ExTru can re-initiate the level of trust periodically after T messages where T <; N, to protect the communication against side-channel and scan-based attacks (e.g. SAT attack). Furthermore, we demonstrate that by properly configuring the value of T, ExTru not only increases the strength of security from per “device” to per “message”, it also significantly improves energy saving as well as throughput vs. an architecture that only uses a conventional side-channel resistant block/stream cipher.