Highly-secure scattering-media-based key storage

Since all the secrets are buried in the secret key, securely storing the secret keys plays a significant role in our modern information society. To avoid the risk of illegally duplicating the stored secret keys, Pappu et al. (Science 297, 2002) proposed an alternative strategy to authenticate a legal user, but not encrypt anything, by introducing a high security-level physical identity token which is well-known as the Physical Unclonable Function (PUF). However, it is incapable of keeping the already existing digital keys away from being duplicated. Here, by modifying the Wavefront Shaping (WS) technique, we present an idea to build a mapping relationship between any easy-to-duplicate digital key and an unclonable scattering media (e.g. ground glass) that is full of uncountable microparticles, and we named it the Unclonable Equivalent Key (UEK). Theoretical analysis and optical experiments were carried out to demonstrate its feasibility, especially its secure and robust performance assisted by an easy-to-implement alignment strategy.