Various embodiments include a method of tracking a chain of custody of an item in a supply chain. A computer system implements a computer interface with a distributed consensus network comprised of computing devices configured to verify one or more waiting transaction records for addition into one or more blocks in a block chain representing a cryptographically verifiable ledger. The order of the block chain is cryptographically protected against tampering by the computing devices. The computer system can track provenance of the item by identifying an existing record in the block chain. The existing record can place a first quantity of a first stock keeping unit (SKU) at a first address. The computer system can then unitize the item by publishing a new record to the block chain. The new record indicates the existing record as a source record and associates a new SKU with a destination address.