diff --git a/doc/API.md b/doc/API.md index 501562c1..35db17d1 100644 --- a/doc/API.md +++ b/doc/API.md @@ -287,8 +287,8 @@ Create a transaction that sweeps all coins for which a timelocked recovery path currently available to a provided address with the provided feerate. The `timelock` parameter can be used to specify which recovery path to use. By default, -we'll use the first recovery path available. If created for a later timelock a recovery -transaction may be satisfied using an earlier timelock but not the opposite. +we'll use the first recovery path available. The provided timelock must match the value of one +of the recovery path. Due to the fact coins are generally received at different block heights, not all coins may be spendable through a single recovery path at the same time. @@ -296,6 +296,14 @@ spendable through a single recovery path at the same time. This command will error if no such coins are available or the sum of their value is not enough to cover the requested feerate. +Note that although a transaction created for a later available timelock can be satisfied using the +keys for an earlier timelock, a PSBT created with this command will only be usable for a single +recovery path. If the user creates a PSBT for recovery path "B" and then ends up willing to satisfy +it using signatures for earlier recovery path "A", they will have to create a new recovery PSBT for +path "A" using `createrecovery`. This is because we do not include the information necessary to sign +using other recovery paths to workaround some signing devices' surprising behaviour. (See +https://github.com/wizardsardine/liana/pull/706#issuecomment-1744705808 for more details.) + #### Request | Field | Type | Description | diff --git a/src/commands/mod.rs b/src/commands/mod.rs index fb2c2b22..ff1f5345 100644 --- a/src/commands/mod.rs +++ b/src/commands/mod.rs @@ -7,7 +7,8 @@ mod utils; use crate::{ bitcoin::BitcoinInterface, database::{Coin, DatabaseInterface}, - descriptors, DaemonControl, VERSION, + descriptors::{self, keys}, + DaemonControl, VERSION, }; pub use crate::database::{CoinStatus, LabelItem}; @@ -71,6 +72,7 @@ pub enum CommandError { InsaneRescanTimestamp(u32), /// An error that might occur in the racy rescan triggering logic. RescanTrigger(String), + UnknownRecoveryTimelock(u16), RecoveryNotAvailable, } @@ -132,6 +134,7 @@ impl fmt::Display for CommandError { ), Self::InsaneRescanTimestamp(t) => write!(f, "Insane timestamp '{}'.", t), Self::RescanTrigger(s) => write!(f, "Error while starting rescan: '{}'", s), + Self::UnknownRecoveryTimelock(tl) => write!(f, "Provided timelock does not correspond to any recovery path: '{}'.", tl), Self::RecoveryNotAvailable => write!( f, "No coin currently spendable through this timelocked recovery path." @@ -345,6 +348,23 @@ impl DaemonControl { } let mut db_conn = self.db.connection(); + // Some signing devices (such as the Bitbox02) would not sign for all keys present in a + // script. This can lead to disruptions. For instance it could not provide a signature for + // the same key across a PSBT inputs. (See + // https://github.com/wizardsardine/liana/pull/706#issuecomment-1744705808 for details.) + // Therefore, only include in the PSBT_IN_BIP32_DERIVATION field the keys for the spending + // path we are interested in. Here the primary path. This guides the signer to sign for + // what we expect, and as long as the same signer isn't reused within the same spending + // path the signatures it will return will be consistent across inputs. + let (_, prim_path_origins) = self + .config + .main_descriptor + .policy() + .primary_path() + .thresh_origins(); + let is_prim_path_key = + |pubkey: &keys::DerivedPublicKey| prim_path_origins.contains_key(&pubkey.origin.0); + // Iterate through given outpoints to fetch the coins (hence checking their existence // at the same time). We checked there is at least one, therefore after this loop the // list of coins is not empty. @@ -393,7 +413,7 @@ impl DaemonControl { script_pubkey: coin_desc.script_pubkey(), }); let non_witness_utxo = spent_txs.get(op).cloned(); - let bip32_derivation = coin_desc.bip32_derivations(); + let bip32_derivation = coin_desc.bip32_derivations(is_prim_path_key); psbt_ins.push(PsbtIn { witness_script, witness_utxo, @@ -428,7 +448,9 @@ impl DaemonControl { } else { self.config.main_descriptor.receive_descriptor() }; - desc.derive(index, &self.secp).bip32_derivations() + // NOTE: include all derivations for change outputs, to make sure signers are + // able to re-compute change addresses. + desc.derive(index, &self.secp).bip32_derivations(|_| true) } else { Default::default() }; @@ -506,8 +528,10 @@ impl DaemonControl { // TODO: shuffle once we have Taproot change_txo.value = change_amount.to_sat(); tx.output.push(change_txo); + // NOTE: include all derivations for change outputs, to make sure signers are + // able to re-compute change addresses. psbt_outs.push(PsbtOut { - bip32_derivation: change_desc.bip32_derivations(), + bip32_derivation: change_desc.bip32_derivations(|_| true), ..PsbtOut::default() }); } else if is_self_send { @@ -761,6 +785,30 @@ impl DaemonControl { .unwrap_or(false) }); + // Some signing devices (such as the Bitbox02) would not sign for all keys present in a + // script. This can lead to disruptions. For instance it could not provide a signature for + // the same key across a PSBT inputs. (See + // https://github.com/wizardsardine/liana/pull/706#issuecomment-1744705808 for details.) + // Therefore, only include in the PSBT_IN_BIP32_DERIVATION field the keys for the requested + // recovery path. This guides the signer toward signing only for this path, and as long as + // the same signer isn't reused within the same spending path the signatures it will return + // will be consistent across inputs. + // Note it's particularly unfortunate for a recovery PSBT. This is because absent this + // restriction a (set of) user(s) could satisfy any previously available paths (the primary + // path and any timelocked path which necessitates a lower sequence) to finalize a PSBT. + // Now they can only create and pass around a PSBT that can be used to sign for a single + // recovery path. + let (_, reco_path_origins) = self + .config + .main_descriptor + .policy() + .recovery_paths() + .get(&timelock) + .ok_or(CommandError::UnknownRecoveryTimelock(timelock))? + .thresh_origins(); + let is_key_for_this_path = + |pubkey: &keys::DerivedPublicKey| reco_path_origins.contains_key(&pubkey.origin.0); + // Fill-in the transaction inputs and PSBT inputs information. Record the value // that is fed to the transaction while doing so, to compute the fees afterward. let mut in_value = bitcoin::Amount::from_sat(0); @@ -793,7 +841,7 @@ impl DaemonControl { script_pubkey: coin_desc.script_pubkey(), }); let non_witness_utxo = spent_txs.get(&coin.outpoint).cloned(); - let bip32_derivation = coin_desc.bip32_derivations(); + let bip32_derivation = coin_desc.bip32_derivations(is_key_for_this_path); psbt.inputs.push(PsbtIn { witness_script, witness_utxo, diff --git a/src/descriptors/mod.rs b/src/descriptors/mod.rs index 574b153c..c5c50f50 100644 --- a/src/descriptors/mod.rs +++ b/src/descriptors/mod.rs @@ -378,7 +378,11 @@ impl DerivedSinglePathLianaDesc { self.0.explicit_script().expect("Not a Taproot descriptor") } - pub fn bip32_derivations(&self) -> Bip32Deriv { + /// Get the BIP32 derivations for this derived descriptor, filtered by the given predicate. + pub fn bip32_derivations

(&self, mut predicate: P) -> Bip32Deriv + where + P: FnMut(&DerivedPublicKey) -> bool, + { let ms = match self.0 { descriptor::Descriptor::Wsh(ref wsh) => match wsh.as_inner() { descriptor::WshInner::Ms(ms) => ms, @@ -391,7 +395,13 @@ impl DerivedSinglePathLianaDesc { // For DerivedPublicKey, Pk::Hash == Self. ms.iter_pk() - .map(|k| (k.key.inner, (k.origin.0, k.origin.1))) + .filter_map(|k| { + if predicate(&k) { + Some((k.key.inner, (k.origin.0, k.origin.1))) + } else { + None + } + }) .collect() } } @@ -630,7 +640,7 @@ mod tests { // Sanity check we can call the methods on the derived desc der_desc.script_pubkey(); der_desc.witness_script(); - assert!(!der_desc.bip32_derivations().is_empty()); + assert!(!der_desc.bip32_derivations(|_| true).is_empty()); } #[test] diff --git a/src/jsonrpc/mod.rs b/src/jsonrpc/mod.rs index 6af7b9e8..0293113e 100644 --- a/src/jsonrpc/mod.rs +++ b/src/jsonrpc/mod.rs @@ -164,6 +164,7 @@ impl From for Error { | commands::CommandError::SpendFinalization(..) | commands::CommandError::InsaneRescanTimestamp(..) | commands::CommandError::AlreadyRescanning + | commands::CommandError::UnknownRecoveryTimelock(..) | commands::CommandError::RecoveryNotAvailable => { Error::new(ErrorCode::InvalidParams, e.to_string()) } diff --git a/src/signer.rs b/src/signer.rs index ebce7510..cc1f672b 100644 --- a/src/signer.rs +++ b/src/signer.rs @@ -456,7 +456,7 @@ mod tests { unknown: BTreeMap::new(), inputs: vec![PsbtIn { witness_script: Some(spent_coin_desc.witness_script()), - bip32_derivation: spent_coin_desc.bip32_derivations(), + bip32_derivation: spent_coin_desc.bip32_derivations(|_| true), witness_utxo: Some(bitcoin::TxOut { value: 19_000, script_pubkey: spent_coin_desc.script_pubkey(), @@ -499,7 +499,7 @@ mod tests { let other_spent_coin_desc = desc.receive_descriptor().derive(84.into(), &secp); dummy_psbt.inputs.push(PsbtIn { witness_script: Some(other_spent_coin_desc.witness_script()), - bip32_derivation: other_spent_coin_desc.bip32_derivations(), + bip32_derivation: other_spent_coin_desc.bip32_derivations(|_| true), witness_utxo: Some(bitcoin::TxOut { value: 19_000, script_pubkey: other_spent_coin_desc.script_pubkey(),