Add sign ecdsa method to bitcoin signer

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@leapwallet/leap-keychain",
-  "version": "0.3.3-beta.3",
+  "version": "0.3.4-beta.0",
   "description": "A javascript library for crypto key management",
   "scripts": {
     "test:coverage": "nyc mocha",

src/key/btc-wallet.ts

@@ -6,6 +6,7 @@ import { base64, hex } from '@scure/base';
 import Container from 'typedi';
 import { secp256k1Token } from '../crypto/ecc/secp256k1';
 import { P2Ret } from '@scure/btc-signer/payment';
+import { signSync } from '@noble/secp256k1';
 export type BTCWalletOptions = WalletOptions & { network: typeof NETWORK };
 
 export abstract class BtcWallet {
@@ -50,6 +51,21 @@ export abstract class BtcWallet {
     if (!account.privateKey) throw new Error('Private key not found');
     tx.signIdx(account.privateKey, idx);
   }
+
+  signECDSA(address: string, hash: Uint8Array) {
+    const accounts = this.getAccountsWithPrivKey();
+    const account = accounts.find((account) => account.address === address);
+    if (!account) throw new Error(`No account found for ${address}`);
+    const [signature, recoveryParam] = signSync(hash, account.privateKey, {
+      canonical: true,
+      recovered: true,
+      der: false,
+    });
+    return {
+      signature,
+      recoveryParam,
+    };
+  }
 }
 
 export class BtcWalletHD extends BtcWallet {

src/utils/encode-signature.ts

@@ -23,3 +23,12 @@ export function encodeSecp256k1Pubkey(pubkey: Uint8Array): Pubkey {
     value: base64js.fromByteArray(pubkey),
   };
 }
+
+export function compressSignature(recoveryParam: number, signature: Uint8Array) {
+  if (!(recoveryParam === 0 || recoveryParam === 1 || recoveryParam === 2 || recoveryParam === 3)) {
+    throw new Error('recoveryParam must be equal to 0, 1, 2, or 3');
+  }
+
+  let headerByte = recoveryParam + 27 + 4;
+  return Buffer.concat([Uint8Array.of(headerByte), Uint8Array.from(signature)]).toString('base64');
+}

test/btc-wallet.test.ts

@@ -10,6 +10,8 @@ import { BtcWalletHD, BtcWalletPk } from '../src/key/btc-wallet';
 import expect from 'expect.js';
 import { addresses, btcPrivatekey, mnemonic, sbtcPrivatekey } from './mockdata';
 import { NETWORK, TEST_NETWORK } from '@scure/btc-signer';
+import { base64 } from '@scure/base';
+import { compressSignature } from '../src/utils/encode-signature';
 
 beforeEach(() => {
   setBip39(Bip39);
@@ -68,4 +70,22 @@ describe('generate btc wallet', () => {
     if (!accounts[0]) throw new Error('No accounts found');
     expect(accounts[0].address).to.be(addresses.signet);
   });
+
+  it('signEcdsa: generates correct signature', () => {
+    const wallet = BtcWalletHD.generateWalletFromMnemonic(mnemonic, {
+      addressPrefix: 'bc1q',
+      paths: ["m/84'/0'/0'/0/0"],
+      network: NETWORK,
+    });
+    const [account] = wallet.getAccounts();
+    if (!account) throw new Error();
+
+    const testHash = 'lZ93LI3uk73n7jGU4os1GIWkEz/4vf//AhBR2m5M/9A=';
+
+    const fixture = 'IBU1VH1HFZKtulCFAukOm3JP8QO4ldrqxVohbhY5Qt8YFAxG85AanlP4qPjnOfDlkWGUUTan1gAVad1KcG2FifQ=';
+
+    const { signature, recoveryParam } = wallet.signECDSA(account.address, base64.decode(testHash));
+    const base64Signature = compressSignature(recoveryParam, signature);
+    expect(base64Signature).to.equal(fixture);
+  });
 });