SAFET-HI: Secure Authentication-Based Framework for Encrypted Testing in Heterogeneous Integration

System-in-Packages (SiPs) are gaining traction due to their enhanced performance, high yield rates, and accelerated time-to-market. However, integrating chiplets from untrusted sources introduces security risks during post-integration testing. Malicious chiplets within the SiP can intercept, modify, or block sensitive test data intended for specific chiplets. This article presents SAFET-HI, a framework designed to ensure a secure testing environment for SiPs. Within this framework, sensitive test data are accessible only to authenticated chiplets. To counter sniffing and spoofing attacks, SAFET-HI encrypts sensitive test patterns while maintaining minimal timing overhead. During post-integration testing, another major threat arises from outsourcing test patterns to untrusted testing facilities, increasing the risk of overproduction and counterfeiting. To address this, SAFET-HI incorporates a functional locking mechanism that prevents unauthorized production and distribution of defective SiPs. Additionally, scan encryption blocks are implemented to stop untrusted test facilities from generating a golden response database. To further enhance security, a watermark bitstream is embedded within the SiP to prevent remarking attacks by untrusted distributors. Simulation results show that SAFET-HI incurs area and timing overheads of only 1.42-4.27% and 13.7%, respectively, demonstrating its effectiveness in securing the SiP testing process.