A proof that outlives us.
MedSeal’s signature says we vouch for a scan. The transparency log and its Bitcoin anchor say something stronger: that a record existed at a point in time and has not changed since — provable by anyone, even if MedSeal disappears.
An append-only Merkle log
Every seal becomes a leaf. Leaves hash together in pairs, up a tree, to a single root hash. Because each level depends on the one below, you cannot alter, insert, or remove a leaf without changing the root — and the root is published.
Your scan travels with a small inclusion proof: the handful of sibling hashes needed to recompute the root from your leaf. Anyone can run that computation locally and confirm your scan belongs — without asking us, and without downloading the whole log.
Anchored on Bitcoin, via OpenTimestamps
Periodically we take the log’s current root and submit it to OpenTimestamps, a free, open standard that commits a hash into the Bitcoin blockchain. Once a Bitcoin block includes it, the root — and every scan beneath it — is timestamped in the most independently-verified ledger in existence.
- One anchor covers every scan sealed before it. No per-scan fee, no chain of our own to trust.
- The proof is a small .ots file you can keep. Verifying it needs only the public Bitcoin blockchain — not MedSeal.
- MedSeal re-anchors the latest root and upgrades pending proofs to confirmed Bitcoin blocks automatically, on a schedule — no human required.
Three artifacts, three checks
Each is public and machine-checkable. Together they prove a scan is in the log and the log is fixed in Bitcoin’s history.
Merkle root
GET /merkle/root
The single hash that commits to every sealed scan. Changing, reordering, or dropping any record changes this root.
Inclusion proof
GET /merkle/proof/<i>
The O(log N) sibling hashes that recompute the root from your leaf. Confirms your scan is in the log without trusting the server.
Bitcoin timestamp
POST /merkle/anchor → .ots
An OpenTimestamps proof that the root existed at a Bitcoin block height. Fixes the log in time, permanently and publicly.
What the anchor proves
- The record existed no later than a specific Bitcoin block.
- The log has not been reordered or edited since.
- Your scan is included in that log (via its proof).
What it does not
- It doesn’t prove the scan is medically correct.
- It doesn’t prove who operated the scanner.
- It doesn’t replace the Ed25519 signature — that’s what says MedSeal vouched for it.
Don’t take our word for it.
Check the .ots proof against Bitcoin yourself — with open tools, in a few commands.