@midnight-ntwrk/wallet-sdk-shielded

Manages shielded tokens on the Midnight network using zero-knowledge proofs.

Installation

npm install @midnight-ntwrk/wallet-sdk-shielded

Overview

The Shielded Wallet handles private token operations where transaction values and addresses are hidden from observers while maintaining verifiability. It provides:

• Zero-knowledge proof generation
• Coin commitment tracking
• Encrypted output decryption
• Shielded transfer transactions
• Transaction balancing for shielded tokens

Usage

Starting the Wallet

import { ShieldedWallet } from '@midnight-ntwrk/wallet-sdk-shielded';
import * as ledger from '@midnight-ntwrk/ledger-v7';
import { randomBytes } from 'node:crypto';

// Configuration for the wallet
const configuration = {
  networkId: 'preview',
  provingServerUrl: new URL('http://localhost:6300'),
  relayURL: new URL('ws://localhost:9944'),
  indexerClientConnection: {
    indexerHttpUrl: 'http://localhost:8088/api/v3/graphql',
    indexerWsUrl: 'ws://localhost:8088/api/v3/graphql/ws',
  },
};

// Create secret keys from a shielded seed
const seed = randomBytes(32);
const shieldedSecretKeys = ledger.ZswapSecretKeys.fromSeed(seed);

// Create and start the wallet
const shieldedWallet = ShieldedWallet(configuration).startWithSecretKeys(shieldedSecretKeys);

// Start syncing with the network
await shieldedWallet.start(shieldedSecretKeys);

Alternative: Start with Seed Directly

// Start directly with a shielded seed
const shieldedWallet = ShieldedWallet(configuration).startWithSeed(seed);
await shieldedWallet.start(ledger.ZswapSecretKeys.fromSeed(seed));

Restoring from Serialized State

// Restore a wallet from previously serialized state
const shieldedWallet = ShieldedWallet(configuration).restore(serializedState);
await shieldedWallet.start(shieldedSecretKeys);

Observing State

wallet.state.subscribe((state) => {
  console.log('Progress:', state.state.progress);
  console.log('Coins:', state.state.coins);
});

Creating Transfer Transactions

const tx = await wallet.transferTransaction(shieldedSecretKeys, [
  { type: 'NIGHT', receiverAddress: 'mn_shield-addr1...', amount: 1000n },
]);

Balancing Transactions

const balancingTx = await wallet.balanceTransaction(shieldedSecretKeys, transactionToBalance);

Creating Swap Offers

const swapTx = await wallet.initSwap(
  shieldedSecretKeys,
  { NIGHT: 500n }, // inputs
  [{ type: 'TOKEN_A', receiverAddress: shieldedAddress, amount: 100n }], // outputs
);

Privacy Model

Shielded transactions use zero-knowledge proofs to hide:

• Transaction amounts
• Sender addresses
• Receiver addresses

While still proving:

• The sender has sufficient balance
• No tokens are created or destroyed
• The transaction is valid

Exports

• ShieldedWallet - Main wallet class
• ShieldedWalletState - Wallet state type
• Version 1 exports via @midnight-ntwrk/wallet-sdk-shielded/v1

License

Apache-2.0