Why ordinary cloud storage is not an offline cryptographic vault
Cloud storage is designed for availability. A cryptographic preservation vault is designed to minimize exposure while retaining evidence that the stored material remains complete and unchanged.
Different operating assumptions
Online platforms rely on accounts, networks, software supply chains and provider operations. Those systems can be appropriate for working data, but long-lived encrypted archives may require a smaller and more deliberate attack surface.
Offline does not mean unattended
Cold storage still requires active stewardship. Media must be checked, environmental conditions controlled, integrity measurements compared and aging formats migrated before their readers become scarce.
A recovery path belongs in the design
The archive manifest should describe what was received, how it was preserved and who can authorize retrieval. If decryption is later commissioned, the working copy, compute environment and recovered output should remain within a defined chain of custody.