Add fromMnemonic function

docs/classes/ethereumhdkey.md

@@ -25,6 +25,7 @@
 - [publicExtendedKey](ethereumhdkey.md#publicextendedkey)
 - [fromExtendedKey](ethereumhdkey.md#fromextendedkey)
 - [fromMasterSeed](ethereumhdkey.md#frommasterseed)
+- [fromMnemonic](ethereumhdkey.md#frommnemonic)
 
 ---
 
@@ -36,7 +37,7 @@
 
 ⊕ **new EthereumHDKey**(\_hdkey: _`any`_): [EthereumHDKey](ethereumhdkey.md)
 
-_Defined in [hdkey.ts:21](https://github.com/ethereumjs/ethereumjs-wallet/blob/13fb20d/src/hdkey.ts#L21)_
+_Defined in [hdkey.ts:27](https://github.com/ethereumjs/ethereumjs-wallet/blob/7b6ac09/src/hdkey.ts#L27)_
 
 **Parameters:**
 
@@ -56,7 +57,7 @@ _Defined in [hdkey.ts:21](https://github.com/ethereumjs/ethereumjs-wallet/blob/1
 
 **● \_hdkey**: _`any`_
 
-_Defined in [hdkey.ts:23](https://github.com/ethereumjs/ethereumjs-wallet/blob/13fb20d/src/hdkey.ts#L23)_
+_Defined in [hdkey.ts:27](https://github.com/ethereumjs/ethereumjs-wallet/blob/7b6ac09/src/hdkey.ts#L27)_
 
 ---
 
@@ -68,7 +69,7 @@ _Defined in [hdkey.ts:23](https://github.com/ethereumjs/ethereumjs-wallet/blob/1
 
 ▸ **deriveChild**(index: _`number`_): [EthereumHDKey](ethereumhdkey.md)
 
-_Defined in [hdkey.ts:52](https://github.com/ethereumjs/ethereumjs-wallet/blob/13fb20d/src/hdkey.ts#L52)_
+_Defined in [hdkey.ts:56](https://github.com/ethereumjs/ethereumjs-wallet/blob/7b6ac09/src/hdkey.ts#L56)_
 
 **Parameters:**
 
@@ -86,7 +87,7 @@ _Defined in [hdkey.ts:52](https://github.com/ethereumjs/ethereumjs-wallet/blob/1
 
 ▸ **derivePath**(path: _`string`_): [EthereumHDKey](ethereumhdkey.md)
 
-_Defined in [hdkey.ts:45](https://github.com/ethereumjs/ethereumjs-wallet/blob/13fb20d/src/hdkey.ts#L45)_
+_Defined in [hdkey.ts:49](https://github.com/ethereumjs/ethereumjs-wallet/blob/7b6ac09/src/hdkey.ts#L49)_
 
 **Parameters:**
 
@@ -104,7 +105,7 @@ _Defined in [hdkey.ts:45](https://github.com/ethereumjs/ethereumjs-wallet/blob/1
 
 ▸ **getWallet**(): [Wallet](wallet.md)
 
-_Defined in [hdkey.ts:59](https://github.com/ethereumjs/ethereumjs-wallet/blob/13fb20d/src/hdkey.ts#L59)_
+_Defined in [hdkey.ts:63](https://github.com/ethereumjs/ethereumjs-wallet/blob/7b6ac09/src/hdkey.ts#L63)_
 
 **Returns:** [Wallet](wallet.md)
 
@@ -116,7 +117,7 @@ _Defined in [hdkey.ts:59](https://github.com/ethereumjs/ethereumjs-wallet/blob/1
 
 ▸ **privateExtendedKey**(): `Buffer`
 
-_Defined in [hdkey.ts:28](https://github.com/ethereumjs/ethereumjs-wallet/blob/13fb20d/src/hdkey.ts#L28)_
+_Defined in [hdkey.ts:32](https://github.com/ethereumjs/ethereumjs-wallet/blob/7b6ac09/src/hdkey.ts#L32)_
 
 **Returns:** `Buffer`
 
@@ -128,7 +129,7 @@ _Defined in [hdkey.ts:28](https://github.com/ethereumjs/ethereumjs-wallet/blob/1
 
 ▸ **publicExtendedKey**(): `Buffer`
 
-_Defined in [hdkey.ts:38](https://github.com/ethereumjs/ethereumjs-wallet/blob/13fb20d/src/hdkey.ts#L38)_
+_Defined in [hdkey.ts:42](https://github.com/ethereumjs/ethereumjs-wallet/blob/7b6ac09/src/hdkey.ts#L42)_
 
 **Returns:** `Buffer`
 
@@ -140,7 +141,7 @@ _Defined in [hdkey.ts:38](https://github.com/ethereumjs/ethereumjs-wallet/blob/1
 
 ▸ **fromExtendedKey**(base58Key: _`string`_): [EthereumHDKey](ethereumhdkey.md)
 
-_Defined in [hdkey.ts:19](https://github.com/ethereumjs/ethereumjs-wallet/blob/13fb20d/src/hdkey.ts#L19)_
+_Defined in [hdkey.ts:23](https://github.com/ethereumjs/ethereumjs-wallet/blob/7b6ac09/src/hdkey.ts#L23)_
 
 **Parameters:**
 
@@ -158,7 +159,7 @@ _Defined in [hdkey.ts:19](https://github.com/ethereumjs/ethereumjs-wallet/blob/1
 
 ▸ **fromMasterSeed**(seedBuffer: _`Buffer`_): [EthereumHDKey](ethereumhdkey.md)
 
-_Defined in [hdkey.ts:12](https://github.com/ethereumjs/ethereumjs-wallet/blob/13fb20d/src/hdkey.ts#L12)_
+_Defined in [hdkey.ts:9](https://github.com/ethereumjs/ethereumjs-wallet/blob/7b6ac09/src/hdkey.ts#L9)_
 
 **Parameters:**
 
@@ -169,3 +170,22 @@ _Defined in [hdkey.ts:12](https://github.com/ethereumjs/ethereumjs-wallet/blob/1
 **Returns:** [EthereumHDKey](ethereumhdkey.md)
 
 ---
+
+<a id="frommnemonic"></a>
+
+### `<Static>` fromMnemonic
+
+▸ **fromMnemonic**(mnemonic: _`string`_, passphrase: _`string`_): [EthereumHDKey](ethereumhdkey.md)
+
+_Defined in [hdkey.ts:16](https://github.com/ethereumjs/ethereumjs-wallet/blob/7b6ac09/src/hdkey.ts#L16)_
+
+**Parameters:**
+
+| Name       | Type     |
+| ---------- | -------- |
+| mnemonic | `string` |
+| `Optional` passphrase | `string` |
+
+**Returns:** [EthereumHDKey](ethereumhdkey.md)
+
+---

src/hdkey.ts

@@ -1,17 +1,22 @@
 import { HDKey } from 'ethereum-cryptography/hdkey'
+import { mnemonicToSeedSync } from 'ethereum-cryptography/bip39'
 import Wallet from './index'
 
 export default class EthereumHDKey {
   /**
    * Creates an instance based on a seed.
-   *
-   * For the seed we suggest to use [bip39](https://npmjs.org/package/bip39) to
-   * create one from a BIP39 mnemonic.
    */
   public static fromMasterSeed(seedBuffer: Buffer): EthereumHDKey {
     return new EthereumHDKey(HDKey.fromMasterSeed(seedBuffer))
   }
 
+  /**
+   * Creates an instance based on BIP39 mnemonic phrases
+   */
+  public static fromMnemonic(mnemonic: string, passphrase?: string): EthereumHDKey {
+    return EthereumHDKey.fromMasterSeed(Buffer.from(mnemonicToSeedSync(mnemonic, passphrase)))
+  }
+
   /**
    * Create an instance based on a BIP32 extended private or public key.
    */

test/hdkey.spec.ts

@@ -7,6 +7,9 @@ const fixtureseed = Buffer.from(
   'hex'
 )
 const fixturehd = EthereumHDKey.fromMasterSeed(fixtureseed)
+const fixtureMnemonic = 'awake book subject inch gentle blur grant damage process float month clown'
+const fixtureAddress = '0x4dcccf58c6573eb896250b0c9647a40c1673af44'
+const fixturePrivateKey = '0xf62a8ea4ab7025d151ccd84981c66278d0d3cd58ff837467cdc51229915a22d1'
 
 describe('.fromMasterSeed()', function () {
   it('should work', function () {
@@ -16,6 +19,23 @@ describe('.fromMasterSeed()', function () {
   })
 })
 
+describe('.fromMnemonic()', function () {
+  it('should work', function () {
+    assert.doesNotThrow(function () {
+      EthereumHDKey.fromMnemonic(fixtureMnemonic)
+    })
+  })
+
+  it('should match', function () {
+    const path = "m/44'/60'/0'/0/0"
+    const hdWallet = EthereumHDKey.fromMnemonic(fixtureMnemonic)
+    const wallet = hdWallet.derivePath(path).getWallet()
+
+    assert.strictEqual(wallet.getPrivateKeyString(), fixturePrivateKey)
+    assert.strictEqual(wallet.getAddressString(), fixtureAddress)
+  })
+})
+
 describe('.privateExtendedKey()', function () {
   it('should work', function () {
     assert.strictEqual(