react-native-rapidsnark

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This library is React Native wrapper for the Rapidsnark. It enables the generation of proofs for specified circuits within a React Native environment.

Platform Support

iOS: Compatible with any iOS device with 64 bit architecture.

Version for emulator built without assembly optimizations, resulting in slower performance.

Android: Compatible with arm64-v8a, x86_64 architectures.

Installation

npm i @iden3/react-native-rapidsnark

Usage

groth16Prove

Function takes path to .zkey file and witness file (base64 encoded) and returns proof and public signals.

Reads .zkey file directly from filesystem.

import {groth16Prove} from "react-native-rapidsnark";

// ...

const zkeyPath = "path/to/zkey";
const wtns = await RNFS.readFile("path/to/wtns", "base64");

const {proof, pub_signals} = await groth16Prove(zkeyPath, wtns);

groth16Verify

Verifies proof and public signals against zkey.

import {groth16Prove, groth16Verify} from "react-native-rapidsnark";

// ...

const zkey = await RNFS.readFile("path/to/zkey", "base64");
const wtns = await RNFS.readFile("path/to/wtns", "base64");
const verificationKey = await RNFS.readFile("path/to/verification_key", "base64");

const {proof, pub_signals} = await groth16Prove(zkey, wtns);

const proofValid = groth16Verify(proof, pub_signals, verificationKey);

groth16PublicBufferSize

Calculates public buffer size for specified zkey.

import { groth16PublicBufferSize } from "react-native-rapidsnark";

// ...

const public_buffer_size_file = await groth16PublicBufferSize("path/to/zkey");

Public buffer size

groth16Prove has an optional proofBufferSize, publicBufferSize and errorBufferSize parameters. If publicBufferSize is too small it will be recalculated automatically by library.

These parameters are used to set the size of the buffers used to store the proof, public signals and error.

If you have embedded circuit in the app, it is recommended to calculate the size of the public buffer once and reuse it. To calculate the size of public buffer call groth16PublicBufferSize.

Troubleshooting

Errors

Invalid witness length.

If you're getting invalid witness length error - check that your witness file is not corrupted and is generated for the same circuit as zkey.

iOS linking troubleshooting

If you get an error like this:

building for 'iOS-simulator', but linking in object file (${SRC_ROOT}/ios/Frameworks/Rapidsnark.xcframework/ios-arm64/librapidsnarkmerged.a[2](fq.o)) built for 'iOS'

1. Open XCode
2. Select your project in the left sidebar
3. Select Build Phases tab
4. Expand Link Binary With Libraries
5. Add Rapidsnark.xcframework from Workspace/Pods folder.

Example App

Check out the example app and example README for a working example.

Custom circuits

Place circuits in example/assets folder and run example/assets/copy_assets.sh to copy them to the app directories. Name them circuit.zkey, witness.wtns and verification_key.json.

License

The project is licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE)
• MIT license (LICENSE-MIT)

at your option.