Most people hear 'blockchain' and think coins. But the useful primitive underneath is much smaller: an append-only log where each entry commits to the previous one.

In ChainVault every upload produces a SHA-256 digest of the file plus the hash of the previous log entry. Change any historical file and every subsequent hash breaks — tamper evidence with nothing more than a hashing function.

The lesson: pick the primitive, not the buzzword. Integrity verification needed hashing and an ordered log, so that is exactly what we shipped.