Context: I want to be able to hash real-world objects
Is it possible to create a substance containing a combination of elements (or isotopes?) in a random and difficult to reproduce (but simple to verify) combination?
For example if the "fingerprint" was 69% X and 31% Y this information can be easily hashed but it should be very difficult to reproduce with exactly that combination. This substance would then be combined with the object in an unobtrusive way and it should be simple to verify that that object has that exact "fingerprint".
In my mind using DNA/RNA in some way seems like a good solution but I believe it's not very stable. I feel it would be useful only if it lasts at least 20-50 years or so.