Building trust you can cryptographically check

Certificate of authenticity, minus the crypto detour

Merchants in jewelry, fine art, collectibles and limited-run goods kept asking for the same thing: a way to prove an item is genuine that a buyer actually trusts, without a hologram sticker that photographs and copies just as easily as the product it is meant to protect.

The tools already doing this leaned on NFTs and blockchain wallets, charged a fee per certificate, and were built around a single niche. None of those three were acceptable for a general-purpose Shopify app: a wallet is a checkout-abandoning step for a buyer who just wants proof, a per-certificate fee punishes merchants for selling more, and jewelry-only presets exclude sneakers, wine, trading cards and every other category where authenticity genuinely matters. Those became the constraints, and the build is the result of taking them seriously.

Six decisions that are not in any feature list

Each of these is a failure we designed out on purpose, most of them specific to making a certificate trustworthy without a blockchain.

1. Trust without a ledger

   Every certificate is signed with an app-wide Ed25519 keypair over a canonical, deterministic representation of its immutable fields, and a SHA-256 fingerprint is taken at issue time. Tampering with any signed field breaks both the fingerprint and the signature, and both are independently checkable from the verification page, with no wallet, gas fee or third-party ledger anywhere in the flow.

2. The editor cannot lie to the merchant

   The certificate layout is built once, in a unit system that renders identically in the drag-and-drop designer and on the public verification page. There is no separate "export renderer" that can silently drift from what the merchant designed, so what is previewed is, byte for byte, what a buyer sees.

3. One order, several certificates, no double-issue

   A single order line can carry a quantity of several units, each needing its own serial number. Allocation runs as one atomic transaction per unit, keyed by a unique constraint on shop, line item and unit index, so a retried webhook can never issue the same certificate twice, and a burst of simultaneous orders can never collide on the same serial.

4. Provenance that outlives the original buyer

   An ownership transfer updates the certificate's current owner while the original issuance record is kept unchanged, so the face of the certificate reflects who owns the item today while the history underneath it stays intact for anyone tracing where it has been.

5. Revocation has to be automatic, not a checklist item

   A certificate's status is derived, not stored as a static flag. Order webhooks for refunds and cancellations flip the underlying state, and the verification page computes Active, Revoked or Expired at render time, so a merchant can never forget to manually revoke a certificate after a refund.

6. One niche should never mean one layout

   Category presets for jewelry, fine art, watches, sneakers, trading cards, wine and more each auto-fill wording, fields and a starter layout suited to that niche, so the app never defaults to a jewelry-shaped certificate for a merchant selling something else entirely.

Verification systems, done without a blockchain

A recurring brief we see is proof: proof an action happened, proof a document is unaltered, proof a party is who they claim to be. That means cryptographic signing over canonical data, a design surface that renders identically everywhere it is shown, idempotent processing of webhooks that can legitimately retry, and derived rather than stored state so nothing needs a human to remember to update it. Those are the parts we had to get right here, and they transfer directly to any client build that needs verifiable proof rather than a database flag.

What the app does, in short

• Auto-issues a serial-numbered, cryptographically signed certificate for every unit on every paid order
• A drag-and-drop designer with a live preview identical to the public certificate
• QR verification, ownership transfer and provenance, and automatic revoke on refund
• Numbered limited editions, back-catalog issuance, and category presets across a dozen niches
• Printable QR labels, scan-to-verify packing slips, NFC tag writing, and Klaviyo and webhook events

Full detail, every feature and the pricing are on the Authentica product page, and the merchant guide is at miko.co.nz/docs/authentica/.

Two screens that carry the trust argument

When software's whole job is proving something is genuine, the interface work is mostly about making that proof legible in one glance.