Layer 01
Foundation.
Anything we sign, anyone can check. In plain terms: a public key, a clock nobody can rewind and a checker you run yourself. Every other layer stands on them. The technical detail is below, for your IT or audit reviewer.
Published keys
The key is public, so the check is yours.
Every Metrecept signature is Ed25519, carried as a compact JWS. The matching public keys are published in a key directory anyone can read, so checking a receipt never needs a Metrecept account or our permission.
The clock
A time we cannot quietly rewrite.
Signatures are grouped into hourly slots. A slot is sealed and timestamped only when it has signatures, so quiet hours have no slot. Each slot is sealed into a Merkle root and anchored to Bitcoin through OpenTimestamps.
The verifier
Runs in your browser.
Paste a receipt and the page checks the signature against the published keys, on your device. Nothing is sent to us to be told it is fine.
What stands on it
Every layer signs against the same base.
Receipts, Extract & Cell, Carve and Compliant browsing are capabilities built on this verification layer. They differ in what they record. They do not differ in how you check them.