Merge pull request #29 from notmandatory/allow-restoring-extended-key-from-mnemonic

Allow restoring extended key from mnemonic

bindings/bdk-kotlin/demo/src/main/kotlin/Main.kt

@@ -44,8 +44,15 @@ val unconfirmedFirstThenByTimestampDescending =
 
 @ExperimentalUnsignedTypes
 fun main(args: Array<String>) {
+    val network = Network.TESTNET
+    val mnemonicType = MnemonicType.WORDS12
+    val password: String? = null
     println("Generating key...")
-    println("${generateExtendedKey(Network.TESTNET, MnemonicType.WORDS12, null)}")
+    val extendedKey = generateExtendedKey(network, mnemonicType, password)
+    println("generated key: $extendedKey")
+    println("Attempting restore extended key...")
+    val restoredKey = restoreExtendedKey(network, extendedKey.mnemonic, password)
+    println("restored key: $restoredKey")
     println("Configuring an in-memory wallet on electrum..")
     val descriptor = "wpkh(tprv8ZgxMBicQKsPeSitUfdxhsVaf4BXAASVAbHypn2jnPcjmQZvqZYkeqx7EHQTWvdubTSDa5ben7zHC7sUsx4d8tbTvWdUtHzR8uhHg2CW7MT/*)"
     val amount = 1000uL
@@ -55,7 +62,7 @@ fun main(args: Array<String>) {
             BlockchainConfig.Electrum(
                     ElectrumConfig("ssl://electrum.blockstream.info:60002", null, 5u, null, 10u)
             )
-    val wallet = OnlineWallet(descriptor, Network.TESTNET, db, client)
+    val wallet = OnlineWallet(descriptor, network, db, client)
     wallet.sync(LogProgress(), null)
     println("Initial wallet balance: ${wallet.getBalance()}")
     println("Please send $amount satoshis to address: ${wallet.getNewAddress()}")

src/bdk.udl

@@ -1,6 +1,8 @@
 namespace bdk {
   [Throws=BdkError]
   ExtendedKeyInfo generate_extended_key(Network network, MnemonicType mnemonicType, string? password);
+  [Throws=BdkError]
+  ExtendedKeyInfo restore_extended_key(Network network, string mnemonic, string? password);
 };
 
 [Error]

src/lib.rs

@@ -288,5 +288,21 @@ fn generate_extended_key(
     })
 }
 
+fn restore_extended_key(
+    network: Network,
+    mnemonic: String,
+    password: Option<String>,
+) -> Result<ExtendedKeyInfo, Error> {
+    let mnemonic = Mnemonic::from_phrase(mnemonic.as_ref(), Language::English).unwrap();
+    let xkey: ExtendedKey = (mnemonic.clone(), password).into_extended_key()?;
+    let xprv = xkey.into_xprv(network).unwrap();
+    let fingerprint = xprv.fingerprint(&Secp256k1::new());
+    Ok(ExtendedKeyInfo {
+        mnemonic: mnemonic.to_string(),
+        xprv: xprv.to_string(),
+        fingerprint: fingerprint.to_string(),
+    })
+}
+
 uniffi::deps::static_assertions::assert_impl_all!(OfflineWallet: Sync, Send);
 uniffi::deps::static_assertions::assert_impl_all!(OnlineWallet: Sync, Send);