Two grades. One is free forever.
everyone else's AI says trust me — a receipt is how your software says check me
Your signature over {digest, pulse, time}
Sign locally with your own Ed25519 key. The only network touch is a free read of the public entropy beacon — the pulse proves the receipt was made after that moment in physics.
- No key, no account, no charge
- Verifies offline in any language with an Ed25519 library
- Proves: this exact file, cited pulse, signed by this key
+ Ledatic witness counter-signature
Our witness key counter-signs the same binding: “we observed digest D at pulse N at server time T.” We set the time, so an anchored receipt cannot be backdated — even by you.
- Backdate-proof and non-repudiable
- Verifier pins our pubkey — forged witness blocks fail closed
- Still verifies offline; the credit is spent at signing, never at verify
the beacon is a live magnetohydrodynamics simulation on our own hardware, publishing a hash-chained pulse stream — watch it at /entropy
Sixty seconds to a verified receipt.
1 · get the client (single file, Python 3)curl -o ledatic_receipts.py https://ledatic.org/sdk/ledatic_receipts.py
pip install cryptographypython3 ledatic_receipts.py sign model_output.json
# receipt: model_output.json.receipt.json pk_fp=59f61409… pulse_id=2667061python3 ledatic_receipts.py verify model_output.json model_output.json.receipt.json
# ok artifact=model_output.json pulse_id=2667061 pk_fp=59f61409…
# exit codes are scriptable: 0 ok · 5 wrong file · 6 forged signatureexport LEDATIC_SDK_API_KEY=lsk_… # from a pack below
python3 ledatic_receipts.py sign model_output.json receipt.json --anchor
# receipt: receipt.json … + witnessed at 1783016427
prefer raw HTTP? the witness endpoint is one POST —
POST /attest/witness with {sha256, pulse_id, value_hex}
and your x-sdk-key header returns the counter-signature.
works from any language. the receipt format is
documented in the reference SDK,
which is written in Rail and signs byte-identical receipts.
Choose how far in you want to be.
access is a key to the instrument. verification and bare signing stay free forever — you only spend when the witness counter-signs. no subscription, no seat, no sales call. the $5 door is always open.
your lsk_… key appears the instant you pay. need an
invoice, a larger allotment, or a private deployment?
talk to us.
What a receipt proves — and what it doesn't.
- A bare receipt proves the exact bytes, the cited pulse, and the signer's key. It binds “not before” the pulse; the created_at time is the signer's own claim.
- An anchored receipt additionally proves the binding was presented to our witness at a server-set time — it cannot be backdated, by anyone, including the signer and including us.
- No receipt proves the content is true, good, or yours. It proves existence, integrity, and time. That's the honest boundary and it is exactly what disputes usually turn on.
- If we disappear, every receipt still verifies: the format is frozen plain JSON, the crypto is standard Ed25519, and the client is a single readable Python file you already downloaded.
- Rotation: the witness pubkey is pinned in the verifier (
45ad2e2d…). If we ever rotate it, old receipts verify against the old pin — published, dated, chained.