schnorr_account_contract.ts

import { Schnorr } from '@aztec/circuits.js/barretenberg';
import { ContractArtifact } from '@aztec/foundation/abi';
import { Fr } from '@aztec/foundation/fields';
import { AuthWitness, CompleteAddress, GrumpkinPrivateKey } from '@aztec/types';

import { AuthWitnessProvider } from '../account/interface.js';
import SchnorrAccountContractArtifact from './artifacts/schnorr_account_contract.json' assert { type: 'json' };
import { BaseAccountContract } from './base_account_contract.js';

/**
 * Account contract that authenticates transactions using Schnorr signatures
 * verified against a Grumpkin public key stored in an immutable encrypted note.
 */
export class SchnorrAccountContract extends BaseAccountContract {
  constructor(private signingPrivateKey: GrumpkinPrivateKey) {
    super(SchnorrAccountContractArtifact as ContractArtifact);
  }

  getDeploymentArgs() {
    const signingPublicKey = new Schnorr().computePublicKey(this.signingPrivateKey);
    return [signingPublicKey.x, signingPublicKey.y];
  }

  getAuthWitnessProvider(_address: CompleteAddress): AuthWitnessProvider {
    return new SchnorrAuthWitnessProvider(this.signingPrivateKey);
  }
}

/** Creates auth witnesses using Schnorr signatures. */
class SchnorrAuthWitnessProvider implements AuthWitnessProvider {
  constructor(private signingPrivateKey: GrumpkinPrivateKey) {}

  createAuthWitness(message: Fr): Promise<AuthWitness> {
    const schnorr = new Schnorr();
    const signature = schnorr.constructSignature(message.toBuffer(), this.signingPrivateKey).toBuffer();
    return Promise.resolve(new AuthWitness(message, [...signature]));
  }
}