feat: dfns handler (#45)

* feat: add dfns handler

package.json

@@ -1,7 +1,7 @@
 {
   "type": "module",
   "name": "dlc-btc-lib",
-  "version": "2.4.20",
+  "version": "2.4.21",
   "description": "This library provides a comprehensive set of interfaces and functions for minting dlcBTC tokens on supported blockchains.",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
@@ -59,6 +59,8 @@
     "typescript-eslint": "^7.7.0"
   },
   "dependencies": {
+    "@dfns/sdk": "^0.5.9",
+    "@dfns/sdk-browser": "^0.5.9",
     "@gemwallet/api": "3.8.0",
     "@ledgerhq/hw-app-btc": "10.4.1",
     "@ledgerhq/hw-app-xrp": "6.29.4",

src/dlc-handlers/dfns-dlc-handler.ts

@@ -0,0 +1,369 @@
+import { DfnsDelegatedApiClient } from '@dfns/sdk';
+import { WebAuthnSigner } from '@dfns/sdk-browser';
+import { GenerateSignatureBody, ListWalletsResponse } from '@dfns/sdk/generated/wallets/types.js';
+import { bytesToHex, hexToBytes } from '@noble/hashes/utils';
+import { Transaction, p2tr } from '@scure/btc-signer';
+import { P2TROut } from '@scure/btc-signer/payment';
+import { Network } from 'bitcoinjs-lib';
+
+import {
+  createTaprootMultisigPayment,
+  deriveUnhardenedPublicKey,
+  ecdsaPublicKeyToSchnorr,
+  getBalance,
+  getFeeRate,
+  getInputIndicesByScript,
+  getUnspendableKeyCommittedToUUID,
+} from '../functions/bitcoin/bitcoin-functions.js';
+import {
+  createDepositTransaction,
+  createFundingTransaction,
+  createWithdrawTransaction,
+} from '../functions/bitcoin/psbt-functions.js';
+import { PaymentInformation } from '../models/bitcoin-models.js';
+import { RawVault } from '../models/ethereum-models.js';
+
+export class DFNSDLCHandler {
+  private readonly dfnsDelegatedAPIClient: DfnsDelegatedApiClient;
+  private readonly bitcoinNetwork: Network;
+  private readonly bitcoinBlockchainAPI: string;
+  private readonly bitcoinBlockchainFeeRecommendationAPI: string;
+  private taprootDerivedPublicKey?: string;
+  private dfnsWalletID?: string;
+  public payment?: PaymentInformation;
+
+  constructor(
+    dfnsAppID: string,
+    appBaseURL: string,
+    dfnsAuthToken: string,
+    bitcoinNetwork: Network,
+    bitcoinBlockchainAPI: string,
+    bitcoinBlockchainFeeRecommendationAPI: string
+  ) {
+    this.dfnsDelegatedAPIClient = new DfnsDelegatedApiClient({
+      baseUrl: appBaseURL,
+      appId: dfnsAppID,
+      authToken: dfnsAuthToken,
+    });
+    this.bitcoinBlockchainAPI = bitcoinBlockchainAPI;
+    this.bitcoinBlockchainFeeRecommendationAPI = bitcoinBlockchainFeeRecommendationAPI;
+    this.bitcoinNetwork = bitcoinNetwork;
+  }
+
+  private setPayment(fundingPayment: P2TROut, multisigPayment: P2TROut): void {
+    this.payment = {
+      fundingPayment,
+      multisigPayment,
+    };
+  }
+
+  private getPayment(): PaymentInformation {
+    if (!this.payment) {
+      throw new Error('Payment Information not set');
+    }
+    return this.payment;
+  }
+
+  async getWallets(): Promise<ListWalletsResponse> {
+    try {
+      return await this.dfnsDelegatedAPIClient.wallets.listWallets();
+    } catch (error: any) {
+      throw new Error(`Error fetching wallets: ${error}`);
+    }
+  }
+
+  async initializeWalletByID(dfnsWalletID: string): Promise<void> {
+    try {
+      const dfnsWallet = await this.dfnsDelegatedAPIClient.wallets.getWallet({
+        walletId: dfnsWalletID,
+      });
+      this.setDFNSWalletID(dfnsWallet.id);
+      this.setTaprootDerivedPublicKey(dfnsWallet.signingKey.publicKey);
+    } catch (error: any) {
+      throw new Error(`Error fetching wallet: ${error}`);
+    }
+  }
+
+  setDFNSWalletID(dfnsWalletID: string): void {
+    this.dfnsWalletID = dfnsWalletID;
+  }
+
+  getDFNSWalletID(): string {
+    if (!this.dfnsWalletID) {
+      throw new Error('DFNS Wallet ID not set');
+    }
+    return this.dfnsWalletID;
+  }
+
+  setTaprootDerivedPublicKey(taprootDerivedPublicKey: string): void {
+    this.taprootDerivedPublicKey = taprootDerivedPublicKey;
+  }
+
+  getTaprootDerivedPublicKey(): string {
+    if (!this.taprootDerivedPublicKey) {
+      throw new Error('Taproot Derived Public Key not set');
+    }
+    return this.taprootDerivedPublicKey;
+  }
+
+  getTaprootTweakedPublicKey(): string {
+    if (!this.payment) {
+      throw new Error('Payment Information not set');
+    }
+    return bytesToHex((this.payment.fundingPayment as P2TROut).tweakedPubkey);
+  }
+
+  getVaultRelatedAddress(paymentType: 'funding' | 'multisig'): string {
+    const payment = this.getPayment();
+
+    if (payment === undefined) {
+      throw new Error('Payment Objects have not been set');
+    }
+
+    switch (paymentType) {
+      case 'funding':
+        if (!payment.fundingPayment.address) {
+          throw new Error('Funding Payment Address is undefined');
+        }
+        return payment.fundingPayment.address;
+      case 'multisig':
+        if (!payment.multisigPayment.address) {
+          throw new Error('Taproot Multisig Payment Address is undefined');
+        }
+        return payment.multisigPayment.address;
+      default:
+        throw new Error('Invalid Payment Type');
+    }
+  }
+
+  private async createPayments(
+    vaultUUID: string,
+    attestorGroupPublicKey: string
+  ): Promise<PaymentInformation> {
+    try {
+      if (!this.taprootDerivedPublicKey) {
+        throw new Error('Taproot Derived Public Key not set');
+      }
+
+      const fundingPayment = p2tr(
+        ecdsaPublicKeyToSchnorr(Buffer.from(this.taprootDerivedPublicKey, 'hex')),
+        undefined,
+        this.bitcoinNetwork
+      );
+
+      const unspendablePublicKey = getUnspendableKeyCommittedToUUID(vaultUUID, this.bitcoinNetwork);
+      const unspendableDerivedPublicKey = deriveUnhardenedPublicKey(
+        unspendablePublicKey,
+        this.bitcoinNetwork
+      );
+
+      const attestorDerivedPublicKey = deriveUnhardenedPublicKey(
+        attestorGroupPublicKey,
+        this.bitcoinNetwork
+      );
+
+      const multisigPayment = createTaprootMultisigPayment(
+        unspendableDerivedPublicKey,
+        attestorDerivedPublicKey,
+        Buffer.from(fundingPayment.tweakedPubkey),
+        this.bitcoinNetwork
+      );
+
+      this.setPayment(fundingPayment, multisigPayment);
+
+      return {
+        fundingPayment,
+        multisigPayment,
+      };
+    } catch (error: any) {
+      throw new Error(`Error creating required wallet information: ${error}`);
+    }
+  }
+
+  async createFundingPSBT(
+    vault: RawVault,
+    bitcoinAmount: bigint,
+    attestorGroupPublicKey: string,
+    feeRateMultiplier?: number,
+    customFeeRate?: bigint
+  ): Promise<Transaction> {
+    try {
+      const { fundingPayment, multisigPayment } = await this.createPayments(
+        vault.uuid,
+        attestorGroupPublicKey
+      );
+
+      const feeRate =
+        customFeeRate ??
+        BigInt(await getFeeRate(this.bitcoinBlockchainFeeRecommendationAPI, feeRateMultiplier));
+
+      const addressBalance = await getBalance(fundingPayment, this.bitcoinBlockchainAPI);
+
+      if (BigInt(addressBalance) < vault.valueLocked.toBigInt()) {
+        throw new Error('Insufficient Funds');
+      }
+
+      const fundingTransaction = await createFundingTransaction(
+        this.bitcoinBlockchainAPI,
+        this.bitcoinNetwork,
+        bitcoinAmount,
+        multisigPayment,
+        fundingPayment,
+        feeRate,
+        vault.btcFeeRecipient,
+        vault.btcMintFeeBasisPoints.toBigInt()
+      );
+
+      return fundingTransaction;
+    } catch (error: any) {
+      throw new Error(`Error creating Funding PSBT: ${error}`);
+    }
+  }
+
+  async createWithdrawPSBT(
+    vault: RawVault,
+    withdrawAmount: bigint,
+    attestorGroupPublicKey: string,
+    fundingTransactionID: string,
+    feeRateMultiplier?: number,
+    customFeeRate?: bigint
+  ): Promise<Transaction> {
+    try {
+      const { fundingPayment, multisigPayment } = await this.createPayments(
+        vault.uuid,
+        attestorGroupPublicKey
+      );
+
+      const feeRate =
+        customFeeRate ??
+        BigInt(await getFeeRate(this.bitcoinBlockchainFeeRecommendationAPI, feeRateMultiplier));
+
+      const withdrawTransaction = await createWithdrawTransaction(
+        this.bitcoinBlockchainAPI,
+        this.bitcoinNetwork,
+        withdrawAmount,
+        fundingTransactionID,
+        multisigPayment,
+        fundingPayment,
+        feeRate,
+        vault.btcFeeRecipient,
+        vault.btcRedeemFeeBasisPoints.toBigInt()
+      );
+
+      return withdrawTransaction;
+    } catch (error: any) {
+      throw new Error(`Error creating Withdraw PSBT: ${error}`);
+    }
+  }
+
+  async createDepositPSBT(
+    depositAmount: bigint,
+    vault: RawVault,
+    attestorGroupPublicKey: string,
+    fundingTransactionID: string,
+    feeRateMultiplier?: number,
+    customFeeRate?: bigint
+  ): Promise<Transaction> {
+    const { fundingPayment, multisigPayment } = await this.createPayments(
+      vault.uuid,
+      attestorGroupPublicKey
+    );
+
+    const feeRate =
+      customFeeRate ??
+      BigInt(await getFeeRate(this.bitcoinBlockchainFeeRecommendationAPI, feeRateMultiplier));
+
+    const depositTransaction = await createDepositTransaction(
+      this.bitcoinBlockchainAPI,
+      this.bitcoinNetwork,
+      depositAmount,
+      fundingTransactionID,
+      multisigPayment,
+      fundingPayment,
+      feeRate,
+      vault.btcFeeRecipient,
+      vault.btcMintFeeBasisPoints.toBigInt()
+    );
+
+    return depositTransaction;
+  }
+
+  async signPSBT(
+    transaction: Transaction,
+    transactionType: 'funding' | 'deposit' | 'withdraw'
+  ): Promise<Transaction> {
+    try {
+      const dfnsWalletID = this.getDFNSWalletID();
+
+      const generateSignatureBody: GenerateSignatureBody = {
+        kind: 'Psbt',
+        psbt: bytesToHex(transaction.toPSBT()),
+      };
+
+      const generateSignatureRequest = {
+        walletId: dfnsWalletID,
+        body: generateSignatureBody,
+      };
+
+      const generateSignatureInitResponse =
+        await this.dfnsDelegatedAPIClient.wallets.generateSignatureInit(generateSignatureRequest);
+
+      const webAuthenticator = new WebAuthnSigner();
+      const assertion = await webAuthenticator.sign(generateSignatureInitResponse);
+
+      const generateSignatureCompleteResponse =
+        await this.dfnsDelegatedAPIClient.wallets.generateSignatureComplete(
+          generateSignatureRequest,
+          {
+            challengeIdentifier: generateSignatureInitResponse.challengeIdentifier,
+            firstFactor: assertion,
+          }
+        );
+
+      const signedPSBT = generateSignatureCompleteResponse.signedData;
+
+      if (!signedPSBT) {
+        throw new Error('No signed data returned');
+      }
+
+      const signedTransaction = Transaction.fromPSBT(hexToBytes(signedPSBT.slice(2)));
+
+      const fundingPayment = this.getPayment().fundingPayment;
+
+      this.finalizeTransaction(signedTransaction, transactionType, fundingPayment.script);
+
+      return signedTransaction;
+    } catch (error: any) {
+      throw new Error(`Error signing PSBT: ${error}`);
+    }
+  }
+
+  private finalizeTransaction(
+    signedTransaction: Transaction,
+    transactionType: 'funding' | 'deposit' | 'withdraw',
+    fundingPaymentScript: Uint8Array
+  ): Transaction {
+    switch (transactionType) {
+      case 'funding':
+        // finalize all inputs in the funding transaction since we have
+        // collected all required signatures at this point.
+        signedTransaction.finalize();
+        break;
+      case 'deposit':
+        // only finalize inputs that spend from the funding address,
+        // multisig inputs will be finalized after attestor signatures are added.
+        getInputIndicesByScript(fundingPaymentScript, signedTransaction).forEach(index =>
+          signedTransaction.finalizeIdx(index)
+        );
+        break;
+      case 'withdraw':
+        // skip finalization since withdraw transaction requires additional
+        // attestor signatures before it can be finalized.
+        break;
+
+      default:
+        throw new Error(`Invalid Transaction Type: ${transactionType}`);
+    }
+    return signedTransaction;
+  }
+}

src/index.ts

@@ -1,3 +1,4 @@
+import { DFNSDLCHandler } from './dlc-handlers/dfns-dlc-handler.js';
 import { LedgerDLCHandler } from './dlc-handlers/ledger-dlc-handler.js';
 import { PrivateKeyDLCHandler } from './dlc-handlers/private-key-dlc-handler.js';
 import { SoftwareWalletDLCHandler } from './dlc-handlers/software-wallet-dlc-handler.js';
@@ -16,4 +17,5 @@ export {
   EthereumHandler,
   ProofOfReserveHandler,
   RippleHandler,
+  DFNSDLCHandler,
 };