@pcd/gpc-pcd

@pcd/gpc-pcd

A PCD representating a ZK proof about one or more POD (Provable Object Data) objects using a GPC (General Purpose Circuit). For a full introduction, see the Developer Site.

POD libraries enable any app to create zero-knowledge proofs of cryptographic data. 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 custom cryptography.

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

See the GPCPCD class for more details on the data of a GPC PCD.

Related Packages

• For information about POD objects in Zupass, see the @pcd/pod-pcd package.

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

• To find the binaries required to prove and verify, see the @pcd/proto-pod-gpc-artifacts package. Since these artifacts are large and numerous, you generally won't want to include this package directly into your app bundle.

Package Installation

This package will work either in browser or in a Node.js server. Packaging for a browser requires polyfill for some Node modules, including buffer and constants.

There is a known issue with a dependency fastfile which can be resolved by polyfilling constants as you can see in this example.

Stability and Security

POD and GPC libraries are in beta and subject to change. We encourage devs to try them out and use them for apps, but be aware that updates will come in future.

GPC proofs are considered ephemeral (for now), primarily intended for transactional use cases. Saved proofs may not be verifiable with future versions of code.

These libraries should not be considered secure enough for highly-sensitive use cases yet. The cryptography, circuits, and configuration compiler have not been audited. The proving/verification keys were generated in good faith by a single author, but are not the result of a distributed trusted setup ceremony.