Why hash witnesses drift mid-transfer
Hash values themselves rarely “drift.” The notes around them do. A retry overwrites a field, a tool prints a different algorithm label, or a witness copies only the first half of a digest because the terminal wrapped awkwardly.
Retries need new lines
Never erase the first attempt. Add a new line with attempt number, reason, and full digest. Auditors would rather see a messy successful trail than a tidy fiction.
Algorithm labels travel with the digest
Write “SHA-256” (or whatever you use) on the same line as the hex string. Months later, nobody remembers which checkbox was selected in a GUI.
Second reader reads aloud
The witness should read the digest back in groups while the operator checks the sheet—not the other way around. That single swap catches most transcription errors we see in learner dry-runs.
Module 3 of the flagship studio practices this with intentionally awkward digests.