Lets prefix this with: I really love Transparency Logs! It’s a fairly simple concept: If you hash elements together in a binary tree, you can validate and verify if elements are present on a tree by hashing a couple of elements. This is what is commonly known as a Merkle tree. I forget the math, but if you have a tree with a million items, you would only really need less than 10 hashes (I think) to figure out what the hash of the top node would be.
