Key points
- Cardano is now supported in the Open Wallet Standard (OWS), starting with the v1.4.3 release.
- OWS is open-source software that lets applications and AI agents keep wallets on the machine they run on and sign through one interface across many blockchains.
- Developers can give each agent its own access key and a set of rules, and OWS checks those rules before it signs.
- The Cardano integration handles addresses, signing, and balance lookups. It also passes Cardano transaction details to those rule checks.
- WingRiders built it with coordination and technical review from Input Output Group (IOG) and the Midnight Foundation.
- The OWS maintainers reviewed and merged the code, which is public on GitHub.
The Open Wallet Standard (OWS) now supports Cardano, and the integration is part of the v1.4.3 release. If you build applications or AI agents that manage their own wallets, Cardano sits in the same OWS interface you would use for Ethereum, Solana, or Bitcoin.
How OWS works
OWS is open-source software for managing wallets and signing with them. The wallets stay on the machine that runs OWS, and applications reach them through a software development kit or the ows command-line tool. A wallet created with one works with the other.
The part built for agents is policy-gated signing. A developer can give an agent its own API key and attach policies to that key. When the agent asks OWS to sign something with it, OWS evaluates those policies first. Built-in controls include a chain allowlist, which limits the chains a key can sign on, and an expiry date after which the key stops working.
One Cardano address, two keys
Cardano did not slot into OWS unchanged. Every other chain in the OWS supported-chains table uses a single derivation path for its address. A Cardano base address, the addr1… format most Cardano wallets use, combines two keys: a payment key that controls funds and a stake key used for delegation and rewards. Each key has its own path under Cardano Improvement Proposal 1852 (CIP-1852).
That second key shaped much of the integration. WingRiders extended the OWS signer so it can derive payment and stake keys separately, and the rest of the Cardano support builds on that.
OWS signs Cardano transactions with the payment key. When a transaction also needs the stake key, for example, to delegate stake, OWS adds a second signature with it, as long as the stake key is available.
Message signing lets you pick the address. You can sign with the base address, an enterprise address that uses only the payment key, or a reward address that uses only the stake key.
Balances come from Koios, a community-run API for Cardano, so an application or agent can check what a wallet holds without leaving OWS.
Cardano transactions in policy checks
For policy checks, the integration parses each Cardano transaction and builds the transaction context that OWS policies evaluate. When an agent requests a Cardano transaction signature using its API key, OWS evaluates the policies attached to that key before signing.
Built by WingRiders
The WingRiders team, which runs a decentralized exchange on Cardano, built the integration. Input Output Group (IOG) and the Midnight Foundation coordinated the project and provided technical review throughout development. The OWS maintainers then reviewed the code over several rounds before merging it.
Where to find it
The Cardano code is in pull request #244, and the v1.4.3 release notes list what changed in that release. The OWS repository has the full documentation, including the policy engine and a supported-chains page that now lists Cardano. Questions and feedback can go to the repository's issue tracker.
