flutter_rapidsnark

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

flutter pub add flutter_rapidsnark

Usage

groth16ProveWithZKeyFilePath

Function takes path to .zkey file and witness file as [Uint8List] and returns proof and public signals as record.

Reads .zkey file directly from filesystem.

import 'package:flutter_rapidsnark/flutter_rapidsnark.dart';

// ...

final zkeyPath = "path/to/zkey";
final witness = await File("path/to/wtns").readAsBytes();

final proof = await groth16ProveWithZKeyFilePath(zkeyPath, witness);

groth16Verify

Verifies proof and public signals against zkey.

import 'package:flutter_rapidsnark/flutter_rapidsnark.dart';

// ...

final zkey = await File("path/to/zkey").readAsBytes();
final witness = await File("path/to/wtns").readAsBytes();
final verificationKey = await File("path/to/verification_key").readAsBytes();

final proof = await groth16Prove(zkey, witness);

final proofValid = await groth16Verify(proof.proof, proof.publicSignals, verificationKey);

groth16Prove

Function that takes zkey and witness files as bytes.

proof and pub_signals are JSON encoded strings.

Large circuits might cause OOM. Use with caution.

import 'package:flutter_rapidsnark/flutter_rapidsnark.dart';

// ...

final zkey = await File("path/to/zkey").readAsBytes();
final witness = await File("path/to/wtns").readAsBytes();

final proof = await groth16Prove(zkey, witness);

groth16PublicSizeForZkeyFile

Calculates public buffer size for specified zkey.

import 'package:flutter_rapidsnark/flutter_rapidsnark.dart';

// ...

final publicBufferSize = await groth16PublicSizeForZkeyFile("path/to/zkey");

Public buffer size

Both groth16Prove and groth16ProveWithZKeyFilePath 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 groth16ProveWithZKeyFilePath.

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.

Example App

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

License

flutter_rapidsnark is part of the iden3 project 0KIMS association. Please check the LICENSE file for more details.