Each saved entry is hashed with SHA-256. When you lock the day, those hashes are chained. Change any earlier entry and the chain no longer matches. The PDF includes the chain so someone outside Crewlog can check it.
Tamper-evident is not the same as “a court will accept this.” It means the file can show it was not quietly edited after the lock. Whether that matters in a dispute is a question for your attorney.
We do not use your logs, voice, or photos to train AI models.