react-native-sapling

React Native bindings for airgap-sapling (Zcash Sapling crypto). Compatible with React Native 0.72.x.

All byte arrays are passed and returned as base64 strings in JavaScript.

Installation

npm install react-native-sapling
# or
yarn add react-native-sapling

Android

The library depends on airgap-sapling via JitPack. Ensure your root build.gradle has:

allprojects {
  repositories {
    maven { url 'https://jitpack.io' }
    // ...
  }
}

Then link the native module (React Native 0.72 usually auto-links):

npx react-native link react-native-sapling

iOS

1. Install pods: cd ios && pod install
2. Add the AirGap Sapling Swift package so the native code can use the Sapling library:
   • In Xcode, open your .xcworkspace
   • File → Add Package Dependencies…
   • Enter: https://github.com/airgap-it/airgap-sapling
   • Add the Sapling library to your app target (and ensure it is available to the RNSapling / react_native_sapling target if needed for linking)

Without this package, the iOS bridge still compiles but will return "Sapling package not linked" at runtime.

Usage

import * as Sapling from 'react-native-sapling';

// All arguments that are byte arrays are base64 strings; numeric values are numbers.

// Init parameters (spend + output params as base64)
await Sapling.initParameters(spendParamsBase64, outputParamsBase64);

// Proving context (create once, reuse for building a transaction)
const contextId = await Sapling.initProvingContext();
try {
  // ... use contextId in prepareOutputDescription, prepareSpendDescriptionWithSpendingKey, createBindingSignature
} finally {
  await Sapling.dropProvingContext(contextId);
}

// Keys (seed and derivation path; seed as base64)
const spendingKey = await Sapling.getExtendedSpendingKey(seedBase64, "m/32'/133'/0'");
const viewingKey = await Sapling.getExtendedFullViewingKey(seedBase64, "m/32'/133'/0'");
// Or from spending key:
const viewingKey2 = await Sapling.getExtendedFullViewingKeyFromSpendingKey(spendingKeyBase64);

// Payment address (viewing key + optional index as base64; omit index for default first address)
const address = await Sapling.getPaymentAddress(viewingKeyBase64, null);
const nextAddress = await Sapling.getNextPaymentAddress(viewingKeyBase64, indexBase64);

// Random scalar
const r = await Sapling.randR();

// … and the rest of the API: getProofAuthorizingKey, verifyCommitment, keyAgreement,
// merkleHash, computeNullifier, prepareOutputDescription, preparePartialOutputDescription,
// getRawPaymentAddress, getDiversifierFromRawPaymentAddress, getPkdFromRawPaymentAddress,
// createBindingSignature, prepareSpendDescriptionWithSpendingKey,
// prepareSpendDescriptionWithAuthorizingKey, signSpendDescription,
// getOutgoingViewingKey, getIncomingViewingKey

API (JS)

All methods return Promises. Byte arrays are base64 strings; numeric values are numbers.

Method	Notes
initParameters(spendParamsBase64, outputParamsBase64)	Initialize Sapling parameters
initProvingContext()	Returns contextId (number). Call dropProvingContext(contextId) when done.
dropProvingContext(contextId)	Release proving context
getProofAuthorizingKey(spendingKeyBase64)
verifyCommitment(commitment, address, value, rcm)	Returns boolean
keyAgreement(pBase64, skBase64)
merkleHash(depth, lhsBase64, rhsBase64)
computeNullifier(viewingKey, address, value, rcm, position)
prepareOutputDescription(contextId, viewingKey, address, rcm, value)
preparePartialOutputDescription(contextId, address, rcm, esk, value)
getPaymentAddress(viewingKey, indexBase64 | null)	indexBase64 null = first address
getNextPaymentAddress(viewingKey, indexBase64)
getRawPaymentAddress(incomingViewingKey, diversifier)
getDiversifierFromRawPaymentAddress(address)
getPkdFromRawPaymentAddress(address)
randR()	Random scalar (base64)
createBindingSignature(contextId, balance, sighashBase64)
prepareSpendDescriptionWithSpendingKey(contextId, spendingKey, address, rcm, ar, value, anchor, merklePath)
prepareSpendDescriptionWithAuthorizingKey(contextId, authorizingKey, address, rcm, ar, value, anchor, merklePath)
signSpendDescription(spendDescription, spendingKey, ar, sighash)
getExtendedSpendingKey(seedBase64, derivationPath)
getExtendedFullViewingKey(seedBase64, derivationPath)
getExtendedFullViewingKeyFromSpendingKey(spendingKeyBase64)
getOutgoingViewingKey(viewingKeyBase64)
getIncomingViewingKey(viewingKeyBase64)

License

ISC