Add bip39 vanity seed key format

package.json

@@ -35,6 +35,7 @@
     "xo": "^0.24.0"
   },
   "dependencies": {
+    "bip39": "^3.0.2",
     "bitcoinjs-lib": "^5.0.3",
     "tiny-emitter": "^2.1.0"
   }

src/address-formats/p2pkh.js

@@ -3,7 +3,8 @@ const {base58} = require('./charsets');
 
 const p2pkh = {
 	prefix: '1',
-	charset: base58
+	charset: base58,
+	bip39: '44'
 };
 
 p2pkh.derive = pubkey => {

src/address-formats/p2wpkh-p2sh.js

@@ -3,7 +3,8 @@ const {base58} = require('./charsets');
 
 const p2wpkhp2sh = {
 	prefix: '3',
-	charset: base58
+	charset: base58,
+	bip39: '49'
 };
 
 p2wpkhp2sh.derive = pubkey => {

src/address-formats/p2wpkh.js

@@ -3,7 +3,8 @@ const {bech32} = require('./charsets');
 
 const p2wpkh = {
 	prefix: 'bc1q',
-	charset: bech32
+	charset: bech32,
+	bip39: '84'
 };
 
 p2wpkh.derive = pubkey => {

src/index.js

@@ -3,7 +3,8 @@ const Emitter = require('tiny-emitter');
 const ONE_SECOND = 1000;
 
 const keyFormats = new Map(Object.entries({
-	wif: require('./key-formats/wif')
+	wif: require('./key-formats/wif'),
+	bip39: require('./key-formats/bip39')
 }));
 
 const addressFormats = new Map(Object.entries({
@@ -35,6 +36,8 @@ class Vain extends Emitter {
 		return new Promise(resolve => {
 			const startTime = Date.now();
 
+			const {generateKey, addressFormat} = this;
+
 			let found;
 			let attempts = 0;
 			let keyData;
@@ -44,8 +47,8 @@ class Vain extends Emitter {
 			while (!found) {
 				attempts++;
 
-				keyData = this.generateKey();
-				address = this.addressFormat.derive(keyData.publicKey);
+				keyData = generateKey({addressFormat});
+				address = addressFormat.derive(keyData.publicKey);
 
 				if (address.startsWith(this.prefix)) {
 					found = true;

src/key-formats/bip39.js

@@ -0,0 +1,20 @@
+const bip39 = require('bip39');
+const bitcoin = require('bitcoinjs-lib');
+
+const generatebip39Key = ({addressFormat}) => {
+	const mnemonic = bip39.generateMnemonic();
+	const seed = bip39.mnemonicToSeedSync(mnemonic);
+
+	const node = bitcoin.bip32.fromSeed(seed);
+	const derivationPath = `m/${addressFormat.bip39}'/0'/0'/0/0`;
+	const {publicKey} = node.derivePath(derivationPath);
+
+	const format = () => ({
+		derivationPath,
+		mnemonic
+	});
+
+	return {publicKey, format};
+};
+
+module.exports = generatebip39Key;

test/unit.js

@@ -1,5 +1,6 @@
 import test from 'ava';
 import * as bitcoin from 'bitcoinjs-lib';
+import * as bip39 from 'bip39';
 import Vain from '..';
 
 test('Vain is exported', t => {
@@ -53,6 +54,62 @@ test('Vain derives a p2wpkh vanity address', async t => {
 	t.is(address, wifAddress);
 });
 
+test('Vain derives a p2pkh vanity seed', async t => {
+	const options = {
+		keyFormat: 'bip39',
+		addressFormat: 'p2pkh',
+		prefix: 'A'
+	};
+	const vain = new Vain(options);
+	const {address, derivationPath, mnemonic} = await vain.start();
+
+	const seed = await bip39.mnemonicToSeed(mnemonic);
+	const node = bitcoin.bip32.fromSeed(seed);
+	const {publicKey} = node.derivePath(derivationPath);
+	const {address: seedAddress} = bitcoin.payments.p2pkh({pubkey: publicKey});
+
+	t.true(address.startsWith(`1${options.prefix}`));
+	t.is(address, seedAddress);
+});
+
+test('Vain derives a p2wpkh-p2sh vanity seed', async t => {
+	const options = {
+		keyFormat: 'bip39',
+		addressFormat: 'p2wpkh-p2sh',
+		prefix: 'A'
+	};
+	const vain = new Vain(options);
+	const {address, derivationPath, mnemonic} = await vain.start();
+
+	const seed = await bip39.mnemonicToSeed(mnemonic);
+	const node = bitcoin.bip32.fromSeed(seed);
+	const {publicKey} = node.derivePath(derivationPath);
+	const {address: seedAddress} = bitcoin.payments.p2sh({
+		redeem: bitcoin.payments.p2wpkh({pubkey: publicKey})
+	});
+
+	t.true(address.startsWith(`3${options.prefix}`));
+	t.is(address, seedAddress);
+});
+
+test('Vain derives a p2wpkh vanity seed', async t => {
+	const options = {
+		keyFormat: 'bip39',
+		addressFormat: 'p2wpkh',
+		prefix: 'a'
+	};
+	const vain = new Vain(options);
+	const {address, derivationPath, mnemonic} = await vain.start();
+
+	const seed = await bip39.mnemonicToSeed(mnemonic);
+	const node = bitcoin.bip32.fromSeed(seed);
+	const {publicKey} = node.derivePath(derivationPath);
+	const {address: seedAddress} = bitcoin.payments.p2wpkh({pubkey: publicKey});
+
+	t.true(address.startsWith(`bc1q${options.prefix}`));
+	t.is(address, seedAddress);
+});
+
 test('Vain defaults to p2pkh if no address format is set', async t => {
 	const options = {
 		prefix: 'A'