The Audit Trail Is a Data Structure, Not a Log Message

Logs can explain what a service thought happened. They do not prove what happened. Klevar Docs needed an audit trail for rendered documents, invoice events, credit note applications, signatures, voids, and attachments. The usual answer is an events table. Insert a row whenever something happens. Add timestamps. Keep it forever. That is useful, but it is still just a table unless the table can detect tampering. The hash chain is the difference. Each entity gets its own ordered chain. A row stores