common: add taproot singlesig descriptor support

lwk_bindings/src/signer.rs

@@ -5,13 +5,15 @@ use std::sync::Arc;
 pub enum Singlesig {
     Wpkh,
     ShWpkh,
+    Taproot,
 }
 
 impl From<Singlesig> for lwk_common::Singlesig {
     fn from(singlesig: Singlesig) -> Self {
         match singlesig {
             Singlesig::Wpkh => lwk_common::Singlesig::Wpkh,
             Singlesig::ShWpkh => lwk_common::Singlesig::ShWpkh,
+            Singlesig::Taproot => lwk_common::Singlesig::Taproot,
         }
     }
 }

lwk_cli/src/args.rs

@@ -408,13 +408,15 @@ impl Display for BlindingKeyKind {
 pub enum SinglesigKind {
     Wpkh,
     Shwpkh,
+    Taproot,
 }
 
 impl Display for SinglesigKind {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
             SinglesigKind::Wpkh => write!(f, "wpkh"),
             SinglesigKind::Shwpkh => write!(f, "shwpkh"),
+            SinglesigKind::Taproot => write!(f, "taproot"),
         }
     }
 }

lwk_common/src/descriptor.rs

@@ -20,6 +20,7 @@ pub fn singlesig_desc<S: Signer + ?Sized>(
     let (prefix, path, suffix) = match script_variant {
         Singlesig::Wpkh => ("elwpkh", format!("84h/{coin_type}h/0h"), ""),
         Singlesig::ShWpkh => ("elsh(wpkh", format!("49h/{coin_type}h/0h"), ")"),
+        Singlesig::Taproot => ("eltr", format!("86h/{coin_type}h/0h"), ""),
     };
 
     let fingerprint = signer.fingerprint().map_err(|e| format!("{e:?}"))?;
@@ -108,11 +109,14 @@ pub enum Singlesig {
 
     /// Witness public key hash wrapped in script hash as defined by bip49
     ShWpkh,
+
+    /// Taproot as defined by bip86
+    Taproot,
 }
 
 /// The error type returned by Singlesig::from_str
 #[derive(Error, Debug)]
-#[error("Invalid singlesig variant '{0}' supported variant are: 'wpkh', 'shwpkh'")]
+#[error("Invalid singlesig variant '{0}', supported variants are: 'wpkh', 'shwpkh', 'taproot'")]
 pub struct InvalidSinglesigVariant(String);
 
 impl FromStr for Singlesig {
@@ -122,6 +126,7 @@ impl FromStr for Singlesig {
         Ok(match s {
             "wpkh" => Singlesig::Wpkh,
             "shwpkh" => Singlesig::ShWpkh,
+            "taproot" => Singlesig::Taproot,
             v => return Err(InvalidSinglesigVariant(v.to_string())),
         })
     }
@@ -248,4 +253,19 @@ mod test {
         }
         Bip::from_str("vattelapesca").unwrap_err();
     }
+
+    #[test]
+    fn singlesig_from_str() {
+        use super::Singlesig;
+        assert!(matches!(Singlesig::from_str("wpkh"), Ok(Singlesig::Wpkh)));
+        assert!(matches!(
+            Singlesig::from_str("shwpkh"),
+            Ok(Singlesig::ShWpkh)
+        ));
+        assert!(matches!(
+            Singlesig::from_str("taproot"),
+            Ok(Singlesig::Taproot)
+        ));
+        Singlesig::from_str("invalid").unwrap_err();
+    }
 }

lwk_jade/src/get_receive_address.rs

@@ -20,6 +20,10 @@ pub enum Variant {
     /// Script hash, Witness public key hash AKA nested segwit, BIP49
     #[serde(rename = "sh(wpkh(k))")]
     ShWpkh,
+
+    /// Taproot, BIP86
+    #[serde(rename = "tr(k)")]
+    Taproot,
 }
 
 #[derive(Debug, PartialEq, Eq)]

lwk_ledger/src/asyncr/client.rs

@@ -263,6 +263,7 @@ impl<T: Transport> LiquidClient<T> {
         let purpose = match variant {
             lwk_common::Singlesig::Wpkh => 84,
             lwk_common::Singlesig::ShWpkh => 49,
+            lwk_common::Singlesig::Taproot => 86,
         };
         let path = format!("m/{purpose}h/{coin_type}h/0h")
             .parse()
@@ -281,7 +282,17 @@ impl<T: Transport> LiquidClient<T> {
             .map_err(|e| map_str_err(e, "Failed to get master blinding key"))?;
         let wpk0 = WalletPubKey::from(((fingerprint, path), xpub));
         let ss_keys = vec![wpk0];
-        let desc = format!("ct(slip77({master_blinding_key}),wpkh(@0/**))");
+        let desc = match variant {
+            lwk_common::Singlesig::Wpkh => {
+                format!("ct(slip77({master_blinding_key}),wpkh(@0/**))")
+            }
+            lwk_common::Singlesig::ShWpkh => {
+                format!("ct(slip77({master_blinding_key}),sh(wpkh(@0/**)))")
+            }
+            lwk_common::Singlesig::Taproot => {
+                format!("ct(slip77({master_blinding_key}),tr(@0/**))")
+            }
+        };
         let ss = WalletPolicy::new("".to_string(), version, desc, ss_keys.clone());
         let address = self
             .get_wallet_address(

lwk_rpc_model/src/response.rs

@@ -449,6 +449,9 @@ pub enum WalletType {
     /// Script hash Witness pay to public key hash (nested segwit)
     ShWpkh,
 
+    /// Taproot
+    Taproot,
+
     /// Witnes script hash, multisig N of M
     WshMulti(usize, usize),
 }
@@ -480,6 +483,7 @@ impl std::fmt::Display for WalletType {
             WalletType::Unknown => write!(f, "unknown"),
             WalletType::Wpkh => write!(f, "wpkh"),
             WalletType::ShWpkh => write!(f, "sh_wpkh"),
+            WalletType::Taproot => write!(f, "taproot"),
             WalletType::WshMulti(threshold, num_pubkeys) => {
                 write!(f, "wsh_multi_{threshold}of{num_pubkeys}")
             }

lwk_wasm/src/jade.rs

@@ -215,7 +215,7 @@ impl Jade {
         let network = self.inner.network();
         let mut paths = HashMap::new();
 
-        for purpose in [49, 84, 87] {
+        for purpose in [49, 84, 86, 87] {
             for coin_type in [1, 1776] {
                 let derivation_path_str = format!("m/{purpose}h/{coin_type}h/0h");
                 let derivation_path = DerivationPath::from_str(&derivation_path_str)?;
@@ -245,6 +245,7 @@ impl From<Singlesig> for Variant {
         match v.inner {
             lwk_common::Singlesig::Wpkh => Variant::Wpkh,
             lwk_common::Singlesig::ShWpkh => Variant::ShWpkh,
+            lwk_common::Singlesig::Taproot => Variant::Taproot,
         }
     }
 }
@@ -259,8 +260,11 @@ impl Singlesig {
             "ShWpkh" => Ok(Singlesig {
                 inner: lwk_common::Singlesig::ShWpkh,
             }),
+            "Taproot" => Ok(Singlesig {
+                inner: lwk_common::Singlesig::Taproot,
+            }),
             _ => Err(Error::Generic(
-                "Unsupported variant, possible values are: Wpkh and ShWpkh".to_string(),
+                "Unsupported variant, possible values are: Wpkh, ShWpkh and Taproot".to_string(),
             )),
         }
     }

lwk_wasm/src/jade_websocket.rs

@@ -212,7 +212,7 @@ impl JadeWebSocket {
         let network = self.inner.network();
         let mut paths = HashMap::new();
 
-        for purpose in [49, 84, 87] {
+        for purpose in [49, 84, 86, 87] {
             for coin_type in [1, 1776] {
                 let derivation_path_str = format!("m/{purpose}h/{coin_type}h/0h");
                 let derivation_path = DerivationPath::from_str(&derivation_path_str)?;

lwk_wollet/src/wollet.rs

@@ -1723,6 +1723,31 @@ mod tests {
         }
     }
 
+    #[test]
+    fn taproot_singlesig_desc_format() {
+        let mnemonic = lwk_test_util::TEST_MNEMONIC;
+
+        for is_mainnet in [false, true] {
+            let signer = SwSigner::new(mnemonic, is_mainnet).unwrap();
+            for blinding_variant in [
+                DescriptorBlindingKey::Slip77,
+                DescriptorBlindingKey::Elip151,
+            ] {
+                let desc_str =
+                    singlesig_desc(&signer, Singlesig::Taproot, blinding_variant).unwrap();
+                assert!(desc_str.contains("eltr("), "desc: {desc_str}");
+                assert!(desc_str.contains("86h/"), "desc: {desc_str}");
+                assert!(desc_str.contains("/<0;1>/*)"), "desc: {desc_str}");
+
+                let expected_coin = if is_mainnet { "1776h" } else { "1h" };
+                assert!(desc_str.contains(expected_coin), "desc: {desc_str}");
+
+                // Verify the descriptor parses into a valid WolletDescriptor
+                let _: WolletDescriptor = desc_str.parse().unwrap();
+            }
+        }
+    }
+
     #[test]
     fn test_wollet_status() {
         let bytes = lwk_test_util::update_test_vector_bytes();

lwk_wollet/tests/tr.rs

@@ -1,5 +1,6 @@
 use crate::test_wollet::*;
-use lwk_common::Signer;
+use lwk_common::{singlesig_desc, DescriptorBlindingKey, Signer, Singlesig};
+use lwk_signer::{AnySigner, SwSigner};
 use lwk_test_util::*;
 use lwk_wollet::{ElementsNetwork, WolletBuilder, WolletDescriptor};
 
@@ -79,3 +80,37 @@ async fn test_single_address_tr_async() {
     let utxos = wollet.utxos().unwrap();
     assert_eq!(utxos.len(), 1);
 }
+
+#[test]
+fn test_taproot_singlesig_receive_balance_send() {
+    let env = TestEnvBuilder::from_env().with_electrum().build();
+
+    let signer = SwSigner::new(TEST_MNEMONIC, false).unwrap();
+    let desc_str =
+        singlesig_desc(&signer, Singlesig::Taproot, DescriptorBlindingKey::Slip77).unwrap();
+    let client = test_client_electrum(&env.electrum_url());
+    let mut wallet = TestWollet::new(client, &desc_str);
+
+    // 1. Receive
+    let fund_sat = 1_000_000;
+    wallet.fund(
+        &env,
+        fund_sat,
+        Some(wallet.address()),
+        None,
+    );
+
+    // 2. Check balance
+    let balance = wallet.balance_btc();
+    assert_eq!(balance, fund_sat);
+
+    // 3. Send
+    let signers: [&AnySigner; 1] = [&AnySigner::Software(signer)];
+    wallet.send_btc(&signers, None, None);
+
+    // send_btc(None, None) sends 10_000 sat to self, so balance drops by fee only
+    let balance_after = wallet.balance_btc();
+    assert!(balance_after < balance, "balance should decrease by fee");
+    // 1_000 sat is a generous upper bound for a regtest fee
+    assert!(balance_after > balance - 1_000, "fee should be reasonable");
+}