Allow generating extended keys

src/bdk.udl

@@ -1,5 +1,6 @@
 namespace bdk {
-
+  [Throws=BdkError]
+  ExtendedKeyInfo generate_extended_key(Network network, MnemonicType mnemonicType, string? password);
 };
 
 [Error]
@@ -146,3 +147,17 @@ interface PartiallySignedBitcoinTransaction {
   [Throws=BdkError]
   constructor([ByRef] OnlineWallet wallet, string recipient, u64 amount);
 };
+
+dictionary ExtendedKeyInfo {
+  string mnemonic;
+  string xprv;
+  string fingerprint;
+};
+
+enum MnemonicType {
+  "Words12",
+  "Words15",
+  "Words18",
+  "Words21",
+  "Words24",
+};

src/lib.rs

@@ -1,3 +1,4 @@
+use bdk::bitcoin::secp256k1::Secp256k1;
 use bdk::bitcoin::util::psbt::PartiallySignedTransaction;
 use bdk::bitcoin::{Address, Network};
 use bdk::blockchain::any::{AnyBlockchain, AnyBlockchainConfig};
@@ -7,6 +8,9 @@ use bdk::blockchain::{
 };
 use bdk::database::any::{AnyDatabase, SledDbConfiguration};
 use bdk::database::{AnyDatabaseConfig, ConfigurableDatabase};
+use bdk::keys::bip39::{Language, Mnemonic, MnemonicType};
+use bdk::keys::{DerivableKey, ExtendedKey, GeneratableKey, GeneratedKey};
+use bdk::miniscript::BareCtx;
 use bdk::wallet::AddressIndex;
 use bdk::{ConfirmationTime, Error, SignOptions, Wallet};
 use std::convert::TryFrom;
@@ -260,5 +264,29 @@ impl WalletHolder<AnyBlockchain> for OnlineWallet {
 
 impl OfflineWalletOperations<AnyBlockchain> for OnlineWallet {}
 
+pub struct ExtendedKeyInfo {
+    mnemonic: String,
+    xprv: String,
+    fingerprint: String,
+}
+
+fn generate_extended_key(
+    network: Network,
+    mnemonic_type: MnemonicType,
+    password: Option<String>,
+) -> Result<ExtendedKeyInfo, Error> {
+    let mnemonic: GeneratedKey<_, BareCtx> =
+        Mnemonic::generate((mnemonic_type, Language::English)).unwrap();
+    let mnemonic = mnemonic.into_key();
+    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);