Item hash
The item's composite fingerprint, a SHA-256 hash (prefix 0x13) binding an item's ULID, claims hash, metadata hash, and signing-key ID into one value; it becomes the item's Merkle-tree leaf in a Truestamp block and is the value Truestamp signs, with authorship and ownership deliberately excluded.
Overview
The item hash is the item’s composite fingerprint: a SHA-256 hash under byte prefix 0x13 over a length-prefixed serialization of four fields, the item’s ULID, its claims hash, its metadata hash, and the signing-key ID. It is the value that becomes a Merkle leaf in a Truestamp block at Item Commitment, and the value Truestamp signs with an Ed25519 signature. Who authored or currently owns the item is deliberately excluded from it, so ownership can change hands without invalidating any proof. See the RFC 6962 Merkle tree for how that leaf enters the tree.