Sealmark

Private proof of existence for your Obsidian notes.

Sealmark hashes a note locally, anchors the hash to the Bitcoin blockchain via OpenTimestamps, and lets anyone verify, with standard open-source tools, that the note existed at a given time and has not changed since.

Your content never leaves your machine. Only a hash is ever published. That is the whole point: you can prove you wrote something first without publishing it (unlike a preprint, which makes priority public by making the content public).

Status

v0, validated end-to-end inside Obsidian: the bundled opentimestamps library loads in the renderer and the seal → upgrade → verify flow works on a real vault. The cryptographic core is additionally covered by Node spikes and unit tests. See ARCHITECTURE.md for the architecture and trust model.

How it works

1. Seal: Sealmark reads the note's raw bytes, computes a SHA-256 digest, and submits only that digest to several public OpenTimestamps calendars. You get a pending proof in seconds, stored as a .ots sidecar next to your note.
2. Upgrade: Bitcoin confirmation takes hours. Sealmark re-fetches the completed proof on startup (and on demand), flipping the note to sealed with a block height.
3. Verify: the .ots is a standard OpenTimestamps proof. Anyone can verify it with Sealmark, with the ots CLI, or against a Bitcoin node. No trust in Sealmark or any server is required (a full node is fully offline and trustless; a block explorer is a convenience fallback).

A note whose content changes after sealing shows as Drifted: the old proof stays valid for the bytes it sealed, it just no longer matches the current file.

Commands

• Seal current note
• Upgrade pending seals
• Verify current note seal

Install (manual, for testing)

npm install
npm run build

Then copy main.js and manifest.json into your vault at <vault>/.obsidian/plugins/sealmark/, reload Obsidian, and enable Sealmark in Settings → Community plugins.

Privacy and trust

• Content is hashed locally; only the digest is sent to calendars.
• The default backend is free public OpenTimestamps calendars. An optional hosted backend may be added later, off by default; the plugin is fully functional without it.

Architecture

See ARCHITECTURE.md. The trust core (src/core) is pure TypeScript with no Obsidian dependency; the Obsidian shell (src/obsidian, src/main.ts) is a thin layer over it. All contact with the opentimestamps library is confined to one file (src/core/anchor/public-calendar.ts).

Author

Built by Yitebeier Aikebaier, who also works on Nexum, a Bitcoin-anchored ledger.

License

MIT.