feat(wasm-utxo): add BIP32Interface support for wallet keys

Add ability to parse and use wallet keys from BIP32Interface objects
instead of requiring xpub strings. This provides a more flexible API
for consuming code that already has BIP32 key objects. The implementation
supports both property access and toBase58() method to extract the keys.

Issue: BTC-2652

Co-authored-by: llm-git <[email protected]>

Author: OttoAllmendinger

packages/wasm-utxo/src/fixed_script_wallet/bip32interface.rs

@@ -0,0 +1,56 @@
+use std::str::FromStr;
+
+use crate::bitcoin::bip32::Xpub;
+use crate::error::WasmMiniscriptError;
+use crate::try_from_js_value::{get_buffer_field, get_field, get_nested_field};
+use wasm_bindgen::JsValue;
+
+fn try_xpub_from_bip32_properties(bip32_key: &JsValue) -> Result<Xpub, WasmMiniscriptError> {
+    // Extract properties using helper functions
+    let version: u32 = get_nested_field(bip32_key, "network.bip32.public")?;
+    let depth: u8 = get_field(bip32_key, "depth")?;
+    let parent_fingerprint: u32 = get_field(bip32_key, "parentFingerprint")?;
+    let index: u32 = get_field(bip32_key, "index")?;
+    let chain_code_bytes: [u8; 32] = get_buffer_field(bip32_key, "chainCode")?;
+    let public_key_bytes: [u8; 33] = get_buffer_field(bip32_key, "publicKey")?;
+
+    // Build BIP32 serialization (78 bytes total)
+    let mut data = Vec::with_capacity(78);
+    data.extend_from_slice(&version.to_be_bytes()); // 4 bytes: version
+    data.push(depth); // 1 byte: depth
+    data.extend_from_slice(&parent_fingerprint.to_be_bytes()); // 4 bytes: parent fingerprint
+    data.extend_from_slice(&index.to_be_bytes()); // 4 bytes: index
+    data.extend_from_slice(&chain_code_bytes); // 32 bytes: chain code
+    data.extend_from_slice(&public_key_bytes); // 33 bytes: public key
+
+    // Use the Xpub::decode method which properly handles network detection and constructs the Xpub
+    Xpub::decode(&data)
+        .map_err(|e| WasmMiniscriptError::new(&format!("Failed to decode xpub: {}", e)))
+}
+
+fn xpub_from_base58_method(bip32_key: &JsValue) -> Result<Xpub, WasmMiniscriptError> {
+    // Fallback: Call toBase58() method on BIP32Interface
+    let to_base58 = js_sys::Reflect::get(bip32_key, &JsValue::from_str("toBase58"))
+        .map_err(|_| WasmMiniscriptError::new("Failed to get 'toBase58' method"))?;
+
+    if !to_base58.is_function() {
+        return Err(WasmMiniscriptError::new("'toBase58' is not a function"));
+    }
+
+    let to_base58_fn = js_sys::Function::from(to_base58);
+    let xpub_str = to_base58_fn
+        .call0(bip32_key)
+        .map_err(|_| WasmMiniscriptError::new("Failed to call 'toBase58'"))?;
+
+    let xpub_string = xpub_str
+        .as_string()
+        .ok_or_else(|| WasmMiniscriptError::new("'toBase58' did not return a string"))?;
+
+    Xpub::from_str(&xpub_string)
+        .map_err(|e| WasmMiniscriptError::new(&format!("Failed to parse xpub: {}", e)))
+}
+
+pub fn xpub_from_bip32interface(bip32_key: &JsValue) -> Result<Xpub, WasmMiniscriptError> {
+    // Try to construct from properties first, fall back to toBase58() if that fails
+    try_xpub_from_bip32_properties(bip32_key).or_else(|_| xpub_from_base58_method(bip32_key))
+}

packages/wasm-utxo/src/fixed_script_wallet/mod.rs

@@ -1,5 +1,6 @@
 /// This module contains code for the BitGo Fixed Script Wallets.
 /// These are not based on descriptors.
+mod bip32interface;
 mod wallet_keys;
 
 pub mod wallet_scripts;
@@ -30,8 +31,8 @@ impl FixedScriptWallet {
         let chain = Chain::try_from(chain)
             .map_err(|e| WasmMiniscriptError::new(&format!("Invalid chain: {}", e)))?;
 
-        let xpubs = xpub_triple_from_jsvalue(&keys)?;
-        let scripts = WalletScripts::from_xpubs(&xpubs, chain, index);
+        let wallet_keys = RootWalletKeys::from_jsvalue(&keys)?;
+        let scripts = WalletScripts::from_wallet_keys(&wallet_keys, chain, index);
         Ok(scripts.output_script().to_bytes())
     }
 
@@ -43,10 +44,10 @@ impl FixedScriptWallet {
         network: JsValue,
     ) -> Result<String, WasmMiniscriptError> {
         let network = Network::try_from_js_value(&network)?;
-        let xpubs = xpub_triple_from_jsvalue(&keys)?;
+        let wallet_keys = RootWalletKeys::from_jsvalue(&keys)?;
         let chain = Chain::try_from(chain)
             .map_err(|e| WasmMiniscriptError::new(&format!("Invalid chain: {}", e)))?;
-        let scripts = WalletScripts::from_xpubs(&xpubs, chain, index);
+        let scripts = WalletScripts::from_wallet_keys(&wallet_keys, chain, index);
         let script = scripts.output_script();
         let address = crate::address::utxolib_compat::from_output_script_with_network(
             &script,

packages/wasm-utxo/src/fixed_script_wallet/test_utils/mod.rs

@@ -7,6 +7,7 @@ use super::wallet_scripts::{Chain, WalletScripts};
 use crate::bitcoin::bip32::{DerivationPath, Fingerprint, Xpriv, Xpub};
 use crate::bitcoin::psbt::{Input as PsbtInput, Output as PsbtOutput, Psbt};
 use crate::bitcoin::{Transaction, TxIn, TxOut};
+use crate::RootWalletKeys;
 use std::collections::BTreeMap;
 use std::str::FromStr;
 
@@ -31,7 +32,8 @@ pub fn get_test_wallet_keys(seed: &str) -> XpubTriple {
 /// Create a PSBT output for an external wallet (different keys)
 pub fn create_external_output(seed: &str) -> PsbtOutput {
     let xpubs = get_test_wallet_keys(seed);
-    let _scripts = WalletScripts::from_xpubs(&xpubs, Chain::P2wshExternal, 0);
+    let _scripts =
+        WalletScripts::from_wallet_keys(&RootWalletKeys::new(xpubs), Chain::P2wshExternal, 0);
     PsbtOutput {
         bip32_derivation: BTreeMap::new(),
         // witness_script: scripts.witness_script,