@umbra-privacy/web-zk-prover

Browser-compatible Groth16 ZK prover for the Umbra privacy protocol. Generates zero-knowledge proofs required for UTXO creation and claiming operations.

Installation

pnpm add @umbra-privacy/web-zk-prover @umbra-privacy/sdk

@umbra-privacy/sdk is a required peer dependency.

Usage

Import a prover factory for the operation you need, then pass it to the corresponding SDK service function:

import { getUmbraClientFromSigner, getCreateReceiverClaimableUtxoFromPublicBalanceFunction } from "@umbra-privacy/sdk";
import { getCreateReceiverClaimableUtxoFromPublicBalanceProver } from "@umbra-privacy/web-zk-prover";

const zkProver = getCreateReceiverClaimableUtxoFromPublicBalanceProver();

const createUtxo = getCreateReceiverClaimableUtxoFromPublicBalanceFunction(
  { client },
  { zkProver },
);

await createUtxo({
  destinationAddress: recipientAddress,
  mint: MINT,
  amount: 1_000_000n,
});

Available Provers

UTXO Creation

• getCreateSelfClaimableUtxoFromEncryptedBalanceProver() — Self-claimable UTXO from encrypted balance
• getCreateReceiverClaimableUtxoFromEncryptedBalanceProver() — Receiver-claimable UTXO from encrypted balance
• getCreateSelfClaimableUtxoFromPublicBalanceProver() — Self-claimable UTXO from public balance
• getCreateReceiverClaimableUtxoFromPublicBalanceProver() — Receiver-claimable UTXO from public balance

UTXO Claiming

• getClaimSelfClaimableUtxoIntoEncryptedBalanceProver() — Claim self-claimable UTXO into encrypted balance
• getClaimReceiverClaimableUtxoIntoEncryptedBalanceProver() — Claim receiver-claimable UTXO into encrypted balance
• getClaimSelfClaimableUtxoIntoPublicBalanceProver() — Claim self-claimable UTXO into public balance

Registration

• getUserRegistrationProver() — Prove anonymous usage registration

ZK Artifact Delivery

Proving keys (.zkey) and witness calculators (.wasm) are fetched from a CDN at proof time. The default CDN provider is included out of the box:

import { getCdnZkAssetProvider } from "@umbra-privacy/web-zk-prover";

// Uses the default Umbra CDN
const assetProvider = getCdnZkAssetProvider();

You can also import the CDN provider from a dedicated subpath:

import { getCdnZkAssetProvider } from "@umbra-privacy/web-zk-prover/cdn";

To use a custom asset host, implement the IZkAssetProvider interface:

import type { IZkAssetProvider } from "@umbra-privacy/web-zk-prover";

const customProvider: IZkAssetProvider = {
  async getAssetUrls(type, variant) {
    return {
      zkeyUrl: `https://my-cdn.example.com/zk/${type}.zkey`,
      wasmUrl: `https://my-cdn.example.com/zk/${type}.wasm`,
    };
  },
};

Proof Conversion Utilities

Convert between snarkjs proof format and the byte layout expected by on-chain Groth16 verification:

import { convertSnarkjsProofToBytes } from "@umbra-privacy/web-zk-prover";

const proofBytes = convertSnarkjsProofToBytes(snarkjsProof);
// proofBytes.proofA (64 bytes), proofBytes.proofB (128 bytes), proofBytes.proofC (64 bytes)

Requirements

• Node.js 18+ or modern browser
• @umbra-privacy/sdk (peer dependency)
• snarkjs is included as a regular dependency

License

MIT