From 57914c2a61cf891fa7a748d4d7f6fb64b1587888 Mon Sep 17 00:00:00 2001
From: Simon Warta <simon@warta.it>
Date: Wed, 22 Jul 2020 08:40:16 +0200
Subject: [PATCH] Add Secp256k1Wallet.generate

---
 packages/sdk38/src/wallet.spec.ts | 15 +++++++++++++++
 packages/sdk38/src/wallet.ts      | 18 ++++++++++++++++++
 packages/sdk38/types/wallet.d.ts  | 12 ++++++++++++
 3 files changed, 45 insertions(+)

diff --git a/packages/sdk38/src/wallet.spec.ts b/packages/sdk38/src/wallet.spec.ts
index d9992ad2..3e5322ae 100644
--- a/packages/sdk38/src/wallet.spec.ts
+++ b/packages/sdk38/src/wallet.spec.ts
@@ -18,6 +18,21 @@ describe("Secp256k1Wallet", () => {
     });
   });
 
+  describe("generate", () => {
+    it("defaults to 12 words", async () => {
+      const wallet = await Secp256k1Wallet.generate();
+      expect(wallet.mnemonic.split(" ").length).toEqual(12);
+    });
+
+    it("can use different mnemonic lengths", async () => {
+      expect((await Secp256k1Wallet.generate(12)).mnemonic.split(" ").length).toEqual(12);
+      expect((await Secp256k1Wallet.generate(15)).mnemonic.split(" ").length).toEqual(15);
+      expect((await Secp256k1Wallet.generate(18)).mnemonic.split(" ").length).toEqual(18);
+      expect((await Secp256k1Wallet.generate(21)).mnemonic.split(" ").length).toEqual(21);
+      expect((await Secp256k1Wallet.generate(24)).mnemonic.split(" ").length).toEqual(24);
+    });
+  });
+
   describe("getAccounts", () => {
     it("resolves to a list of accounts if enabled", async () => {
       const wallet = await Secp256k1Wallet.fromMnemonic(defaultMnemonic);
diff --git a/packages/sdk38/src/wallet.ts b/packages/sdk38/src/wallet.ts
index 1efb4075..eb3059a3 100644
--- a/packages/sdk38/src/wallet.ts
+++ b/packages/sdk38/src/wallet.ts
@@ -1,6 +1,7 @@
 import {
   Bip39,
   EnglishMnemonic,
+  Random,
   Secp256k1,
   Sha256,
   Sha512,
@@ -76,6 +77,23 @@ export class Secp256k1Wallet implements OfflineSigner {
     return new Secp256k1Wallet(mnemonic, privkey, Secp256k1.compressPubkey(uncompressed), prefix);
   }
 
+  /**
+   * Generates a new wallet with a BIP39 mnemonic of the given length.
+   *
+   * @param length The number of words in the mnemonic (12, 15, 18, 21 or 24).
+   * @param hdPath The BIP-32/SLIP-10 derivation path. Defaults to the Cosmos Hub/ATOM path `m/44'/118'/0'/0/0`.
+   * @param prefix The bech32 address prefix (human readable part). Defaults to "cosmos".
+   */
+  public static async generate(
+    length: 12 | 15 | 18 | 21 | 24 = 12,
+    hdPath: readonly Slip10RawIndex[] = makeCosmoshubPath(0),
+    prefix = "cosmos",
+  ): Promise<Secp256k1Wallet> {
+    const entropyLength = 4 * Math.floor((11 * length) / 33);
+    const entropy = Random.getBytes(entropyLength);
+    const mnemonic = Bip39.encode(entropy);
+    return Secp256k1Wallet.fromMnemonic(mnemonic.toString(), hdPath, prefix);
+  }
 
   private readonly mnemonicData: EnglishMnemonic;
   private readonly pubkey: Uint8Array;
diff --git a/packages/sdk38/types/wallet.d.ts b/packages/sdk38/types/wallet.d.ts
index 0c29481d..0f295b04 100644
--- a/packages/sdk38/types/wallet.d.ts
+++ b/packages/sdk38/types/wallet.d.ts
@@ -28,6 +28,18 @@ export declare class Secp256k1Wallet implements OfflineSigner {
     hdPath?: readonly Slip10RawIndex[],
     prefix?: string,
   ): Promise<Secp256k1Wallet>;
+  /**
+   * Generates a new wallet with a BIP39 mnemonic of the given length.
+   *
+   * @param length The number of words in the mnemonic (12, 15, 18, 21 or 24).
+   * @param hdPath The BIP-32/SLIP-10 derivation path. Defaults to the Cosmos Hub/ATOM path `m/44'/118'/0'/0/0`.
+   * @param prefix The bech32 address prefix (human readable part). Defaults to "cosmos".
+   */
+  static generate(
+    length?: 12 | 15 | 18 | 21 | 24,
+    hdPath?: readonly Slip10RawIndex[],
+    prefix?: string,
+  ): Promise<Secp256k1Wallet>;
   private readonly mnemonicData;
   private readonly pubkey;
   private readonly privkey;