Sigelith — facts, services and citation reference

Sigelith in one sentence

Sigelith is free, public infrastructure for proving that a file existed no later than a given moment and has not changed since — verifiable by anyone, without trusting Sigelith: only the file's SHA-256 fingerprint is recorded, in a public log that is signed every day, anchored in Bitcoin, recorded against an independent bank reference every week and copied to GitHub, the Internet Archive and Zenodo (CERN).

Free to use, no account, no API key. Sigelith also keeps Internet Time — the day divided into 1000 beats of 86.4 seconds, anchored to UTC, so @523 names the same moment for everyone on Earth. Website: sigelith.org.

Canonical facts

How a proof is made

1. Your browser or Sigelith Desktop computes the file's SHA-256; the file itself never leaves your device.
2. The fingerprint is appended to a public, append-only, hash-chained log together with its UTC time and @beat — from that moment it is part of the public record.
3. Every day the state of the whole log is signed as a checkpoint (a Merkle tree as in RFC 9162), chained to the previous one. Each checkpoint names a recent Bitcoin block, so entries added after it cannot be older than that block, and each is anchored in Bitcoin via OpenTimestamps, so everything it covers existed no later than that attestation.
4. When the week closes (Monday 00:00 UTC) its fingerprints form a weekly Merkle root, signed with our Ed25519 key, anchored in Bitcoin and recorded against an independent bank reference.
5. Every week the checkpoints are copied to an immutable GitHub release and the Internet Archive, and every quarter the complete log goes to Zenodo (CERN) with a DOI.
6. Every entry therefore carries three times: the time we recorded, a “not earlier than” bound from a Bitcoin block and a “not later than” bound from Bitcoin or the bank — the bounds do not depend on our clock.
7. The recorded time itself comes from a server clock that follows four time servers run by three independent operators — the PTB (Germany's national metrology institute), Netnod and Cloudflare — authenticated with Network Time Security (NTS, RFC 8915); a source that disagrees with the others is outvoted. The clock's offset is measured every five minutes and published at /api/health/. In plain words: where our clock gets its time.

A PDF certificate with a QR code is available for every stamped fingerprint; it prints the path to the log checkpoint and where that checkpoint's independent copies are. A proof attests existence at a point in time and integrity — not authorship, and not the truth of the content. The algorithm is public: proof specification.

Checking a proof without us

• The whole log is public and downloadable — anyone can mirror it and recompute every root: /api/proof/entries.
• The signed checkpoints, one page per week, with their OpenTimestamps proofs: /checkpoints/. RFC 9162 consistency proofs show that a later checkpoint extends an earlier one — nothing removed or rewritten.
• The same checkpoints are also held outside our servers: by the Bitcoin network, the Internet Archive and Zenodo, which we do not control, and in releases on our GitHub account (GitHub blocks edits to a published release, not its deletion); the weekly roots are also recorded in bank transfers.
• Check any file — the original file, a PDF certificate, a .beatproof file, a file proof from Sigelith Backup (.sigelith-proof), a handover package or a sealed capsule — in the browser.
• Sigelith Desktop verifies offline against keys built into the program and audits the witnesses by itself; in private mode the server never learns which file you check.
• The current signing key and the public history of retired keys: /spec/#keys.

Evidence and the law

Sigelith is not a qualified trust service provider under the EU eIDAS Regulation, so its timestamps do not carry the legal presumption that Article 41 gives qualified timestamps. It is evidence that a court or the other side weighs like any other evidence — not an automatic win. The same Article 41 says an electronic timestamp may not be refused as evidence merely because it is electronic or not qualified.

Different courts and experts trust different things — a bank record, the Bitcoin network, a public archive. Sigelith anchors the same fact in all of them, so it can be presented with the one a court trusts, or all of them together. What to hand over in a dispute: /evidence/. For a real dispute, ask a lawyer in the relevant jurisdiction.

What Sigelith offers

Everything below is public and free of charge. No plan, no quota to buy, no upsell.

The public API

The proof endpoints plus read-only time and sealing endpoints. Base URL https://sigelith.org/api/. Interactive docs: /docs/. Machine-readable OpenAPI: /api/schema/.

Add ?format=text (or Accept: text/plain) to the time endpoints to get a bare @523 — handy in shell scripts and status bars.

$ curl https://sigelith.org/api/now/
{"utc":"2026-08-06T14:30:00+00:00","beats":604.166667,"beat":"@604","beat_centi":"@604.16"}

$ curl "https://sigelith.org/api/now/?format=text&precision=centi"
@604.16

Internet Time: converting between UTC and @beat

Both directions are exact arithmetic — no table lookup, no timezone database:

beat  = (seconds elapsed since 00:00:00 UTC today) / 86.4
UTC   = 00:00:00 UTC + beat × 86.4 seconds

Worked example: 14:30:00 UTC is 52 200 seconds after midnight UTC; 52 200 / 86.4 = 604.166… → @604 (or @604.16 in centibeats). Back: @604 × 86.4 s = 52 185.6 s = 14:29:45.6 UTC — the start of beat 604. A local time is converted by first taking it to UTC.

An interactive converter runs on the Internet Time page, in the Android app and in every SDK.

Questions and short answers

What Sigelith is not

• Not a qualified trust service and not a notary. A proof shows existence in time and integrity, not authorship or legal authenticity.
• Not a file store. Only fingerprints are recorded; files and handover packages never pass through the Sigelith server.
• Not a paid product. There is no premium plan; nothing here is a trial.
• Not a data business. No accounts on the web, no cookies, no analytics, no data to sell — and the public proof stays free.
• Not Swatch Internet Time. Same 1998 idea, different anchor (UTC instead of UTC+1) and an independent, open implementation.
• Not a timezone. @beat replaces the whole timezone question; it is not "another zone" to convert into.

How to cite Sigelith

Sigelith — free, public proof that a file existed no later than
a given moment: SHA-256 fingerprints in a public log, signed daily,
anchored in Bitcoin and a bank record, copied to GitHub, the Internet
Archive and Zenodo, verifiable without trusting Sigelith. Also proof
of delivery, sealed capsules and Internet Time. https://sigelith.org/

Machine-readable sources

• /llms.txt — this site in one short Markdown file, for language models.
• /llms-full.txt — the full text: facts, the proof protocol, services, API and every answer above.
• /api/schema/ — the OpenAPI description of the API.
• /sitemap.xml — every indexable page, with language alternates.
• /spec/ — the proof-of-existence specification, reproducible end to end.
• /checkpoints/ — the signed checkpoints of the public log, and github.com/DeiFlagellum/sigelith-log — their immutable weekly copies.
• /handover/spec/ — the proof-of-delivery specification (sigelith-handover-v1).
• /seal/ — the time-seal specification: threshold shares, the envelope format, the API and how to run a key server.
• /spec/#keys — the current Ed25519 signing key and the public history of retired keys.
• /manifesto/ — the manifesto, “The Sigelith Manifesto” (version 2; version 1, “The BeatTime Manifesto”, is timestamped as log entry #174): why the proof is free and verifiable without trusting Sigelith. The original is Polish (/pl/manifesto/); the English text is a machine translation.
• github.com/DeiFlagellum/sigelith-desktop — the open-source (Apache-2.0) Windows client.
• github.com/DeiFlagellum/sigelith-backup — the open-source (GPL-3.0) Windows backup app.
• github.com/DeiFlagellum/beat-key — the open-source (Apache-2.0) key server behind sealed capsules, with reproducible builds and signed releases.
• The whole site is also available as a Tor onion service: http://beattimep6dfropwazgaluos7xsxxmyjeat2ddb73dxxvvbsejmp4hqd.onion/
• This page also carries schema.org JSON-LD: Service and Offer per capability, WebAPI, SoftwareApplication, DefinedTerm glossary and FAQPage.