File encryption

How it works

A password-protected ZIP and an age or GPG file are file encryption. The transfer can be plain and the file still unreadable. Key handling is the product. A lost passphrase is a lost file.

A 2 GB archive is encrypted, then mailed as a link. The server holds ciphertext. The passphrase goes by phone. A stolen bucket snapshot does not open the archive. A passphrase in the same mail would have.

How it differs

File encryption is not TLS. TLS ends at the server. File encryption survives the server.

Double encryption is fine. Forgetting the passphrase is the failure mode.

Test a decrypt on a second machine before you delete the original.

On the ticket

• The practical close is a log line: time, actor, byte count, result.
• Without that line the transfer is a story.
• With it, the next person can see whether this door did what the ticket claimed.
• If the path is shared, say so in the partner profile so a later change does not silently pick a different limit, key, or region.
• On a real ticket, write down the door, the byte count, and the clock.
• For file encryption, that means naming the host or bucket, the expected size, and the time the other side must have a complete file.
• A progress bar is not that record.
• A 200 response that arrives before the complete call is not that record.
• If a retry is allowed, say how many and whether it resumes.
• If a person must approve the send, name the person.
• Partners who receive file encryption files should match on hash or size before they import.
• A same-length corrupt file passes a size check and fails a hash.
• Keep the published hash off the only channel an attacker can edit, or treat it as a corruption check rather than a substitution check.
• When the path changes, new key, new region, new cap, update the profile the same day so the next run does not use a stale limit.