feat: Add support for bip39 mnemonics for the derivation

packages/walletkit/package.json

@@ -61,6 +61,7 @@
     "@tonconnect/protocol": "^2.3.0",
     "@tonconnect/sdk": "^3.2.0",
     "@truecarry/tlb-abi": "^0.2.0",
+    "bip39": "^3.1.0",
     "lru-cache": "^11.1.0",
     "node-hid": "^3.2.0",
     "vite": "^7.1.3"

packages/walletkit/src/utils/mnemonic.ts

@@ -1,18 +1,31 @@
-import { mnemonicToWalletKey, mnemonicNew } from '@ton/crypto';
+import { mnemonicToWalletKey, mnemonicNew, keyPairFromSeed, deriveEd25519Path } from '@ton/crypto';
+import { mnemonicToSeed as bip39MnemonicToSeed } from 'bip39';
 
 import { WalletKitError, ERROR_CODES } from '../errors';
 
+async function bip39ToPrivateKey(mnemonic: string[]) {
+    const seed = await bip39MnemonicToSeed(mnemonic.join(' '));
+    const TON_DERIVATION_PATH = [44, 607, 0];
+    const seedContainer = await deriveEd25519Path(seed, TON_DERIVATION_PATH);
+    return keyPairFromSeed(seedContainer.subarray(0, 32));
+}
+
+/**
+ * Convert a mnemonic to a key pair
+ * @param mnemonic - The mnemonic to convert, can be an array of strings or a string. 12 or 24 words
+ * @param mnemonicType - The type of mnemonic to convert, can be 'ton' or 'bip39'
+ * @returns The key pair
+ */
 export async function MnemonicToKeyPair(
     mnemonic: string | string[],
     mnemonicType: 'ton' | 'bip39' = 'ton',
 ): Promise<{ publicKey: Uint8Array; secretKey: Uint8Array }> {
     const mnemonicArray = Array.isArray(mnemonic) ? mnemonic : mnemonic.split(' ');
-    if (mnemonicArray.length !== 24) {
+
+    if (mnemonicArray.length !== 12 && mnemonicArray.length !== 24) {
         throw new WalletKitError(
             ERROR_CODES.VALIDATION_ERROR,
-            `Invalid mnemonic length: expected 24 words, got ${mnemonicArray.length}`,
-            undefined,
-            { receivedLength: mnemonicArray.length, expectedLength: 24 },
+            `Invalid mnemonic length: expected 12 or 24 words, got ${mnemonicArray.length}`,
         );
     }
 
@@ -24,7 +37,13 @@ export async function MnemonicToKeyPair(
         };
     }
 
-    // TODO bip39 support
+    if (mnemonicType === 'bip39') {
+        const key = await bip39ToPrivateKey(mnemonicArray);
+        return {
+            publicKey: new Uint8Array(key.publicKey),
+            secretKey: new Uint8Array(key.secretKey),
+        };
+    }
 
     throw new WalletKitError(
         ERROR_CODES.VALIDATION_ERROR,