Timed Physical Password or Authentication Keys

Advancements in counterfeit technologies call for nonconventional methodologies to generate unique digital fingerprints to protect high-value and mission-critical resources. The current generation of root-of-trust relies on permanent digital storage, rendering it vulnerable to adversarial attacks due to its permanence. Herein, we introduce the concept of utilizing nanoscale surface stress to drive metastable phase transition as a pathway to physically store information dynamically with high dimensionality. The possibility of fabricating multilevel variables in these keys results in a high entropy system with multiple decryption pathway. Furthermore, due to the metastable state of these keys, a physical timer can be induced through external force, triggering phase relaxation with a predictable decay rate from diffusion flux. This work displays a unique perspective and utilization of phase transitions as information carriers.