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Label 309 Is Now CIP-0190
The Proof of Existence standard we wrote for Cardano has been accepted into the official CIP repository as CIP-0190. Here is what that means, what it does not mean, and what comes next.
Label 309 has been accepted into the official Cardano CIP repository as CIP-0190.
When we relaunched CardanoWall, we made a deliberate choice: the durable artifact would not be our app, our API, or our brand. It would be the standard underneath — a precise, vendor-neutral description of how a Proof of Existence record looks on the Cardano chain, written so that anyone could implement it and no one would have to trust us. Getting that standard into the Cardano Foundation's own CIP repository was the whole point. That has now happened.
What "accepted as CIP-0190" means
A Cardano Improvement Proposal earns its number and lands in the official repository once the editors are satisfied the specification is complete, technically sound, and carries a valid path to adoption. CIP-0190 has cleared that bar: it is merged, it has a permanent number, and it lives at cardano-foundation/CIPs alongside every other Cardano standard. Anyone building a wallet, a viewer, or an auditor can now cite it as a fixed reference.
Two identifiers, and why they are different
It is worth being exact, because the numbers look similar and people conflate them:
- Metadata label 309 is the load-bearing on-chain identifier. It is the integer under which a Proof of Existence record is written in Cardano transaction metadata, reserved in the CIP-10 registry. Implementations cite the standard by this label.
- CIP-0190 is the number of the proposal document itself.
The informal name "CIP-309" was never an assigned CIP number — it only ever came from the metadata label. The metadata label is 309; the assigned CIP number is CIP-0190. Nothing on the wire changes because of the number.
What it does not mean yet
Being accepted is not the same as being finished. In CIP terms, CIP-0190's lifecycle status is Proposed, not yet Active. "Active" is a further step that requires demonstrating the standard's own acceptance criteria in public: independent implementations, real records on mainnet across every profile, wallet-signing interop shown with mainstream wallets, and an external cryptographic review of the sealed construction. We wrote those criteria into the specification ourselves, and we intend to close them in the open. Accepted is the milestone that matters today; Active is the one we work toward next.
What does not change
Everything that made Label 309 worth writing stays exactly as it was. The standard is still issuer-agnostic: any wallet can publish. It is still standalone-verifiable: anyone can check a proof from just the transaction and a public block explorer, with no issuer server in the loop. CardanoWall remains one implementation of it, not the owner of it. The specification, the SDKs, and the gateway underneath are open source and belong to everyone.
You can read the standard at label309.org and the accepted CIP at CIP-0190.