Overview

An inclusion proof, also called an audit proof, is the short list of sibling hashes (the audit path) that lets a verifier walk from one Merkle leaf up to the tree’s root, proving the leaf is a member of that root without revealing or requiring any other leaves; for a tree with N leaves the proof holds only about log2(N) hashes. Truestamp uses inclusion proofs twice in every proof bundle: the ip proof walks the subject hash into the block’s Merkle root, and each external commitment’s ep proof walks the block hash into the epoch root recorded on a public blockchain. On the wire the proof travels in a compact binary encoding. The verification walk, and the exact set of facts an inclusion proof does and does not establish, are covered in Merkle inclusion proofs.