A PCD representating an object in the POD (Provable Object Data) format, allowing it to be manipulated by generic apps like Zupass. For a full introduction, see the Developer Site.

POD is a format enabling any app to flexibly create cryptographic data and make zero-knowledge proofs about it. A POD could represent your ticket to an event, a secure message, a collectible badge, or an item in a role-playing game. Using PODs, developers can create ZK-enabled apps without the effort and risk of developing their own cryptography.

ZK proofs about PODs use General Purpose Circuits (GPC) which can prove many different things about a POD without revealing it all. GPCs use human-readable configuration and pre-compiled circuits so no knowledge of circuit programming is required.

See the PODPCD class for more details on the data of a POD PCD.

Related Packages

• For information about making POD objects, see the @pcd/pod package.

• For information about making proofs about PODs in Zupass, see the @pcd/gpc-pcd package.

Stability and Security

POD and GPC libraries are experimental and subject to change. We encourage devs to try them out and use them for apps, but maybe don’t rely on them for the most sensitive use cases yet.

The PODs themselves are persistent data, and we expect to maintain backward-compatibility when we make changes to the format, but new code may be required to handle formar versioning. Library interfaces may also change. Any breaking changes will be reflected in the NPM versions using standard semantic versioning.