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descriptors: use the origin as xpub UID in partial spend info, not the fingerprint

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We were using the fingerprint as a stable unique identifier for xpubs in
a descriptor. It's not. For instance, what if a single signer is used
both in the primary and recovery path? The same fingerprint would appear
in both paths and we would mix up the signatures for both paths (ie if a
signature for each was provided, we would count each path as having 2
signatures).
This commit is contained in:
Antoine Poinsot 2023-02-05 14:31:24 +01:00
parent 4af1a12a2a
commit fcc1c21dbb
No known key found for this signature in database
GPG Key ID: E13FC145CD3F4304
1 changed files with 74 additions and 31 deletions
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105
src/descriptors.rs
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@ -232,16 +232,13 @@ fn is_valid_desc_key(key: &descriptor::DescriptorPublicKey) -> bool {
}
}
// Get the fingerprint for the key in a multipath descriptors.
// Get the origin of a key in a multipath descriptors.
// Returns None if the given key isn't a multixpub.
fn key_fingerprint(key: &descriptor::DescriptorPublicKey) -> Option<bip32::Fingerprint> {
fn key_origin(
key: &descriptor::DescriptorPublicKey,
) -> Option<&(bip32::Fingerprint, bip32::DerivationPath)> {
match key {
descriptor::DescriptorPublicKey::MultiXPub(ref xpub) => Some(
xpub.origin
.as_ref()
.map(|o| o.0)
.unwrap_or_else(|| xpub.xkey.fingerprint()),
),
descriptor::DescriptorPublicKey::MultiXPub(ref xpub) => xpub.origin.as_ref(),
_ => None,
}
}
@ -513,17 +510,25 @@ impl PathInfo {
/// Get the required number of keys for spending through this path, and the set of keys
/// that can be used to provide a signature for this path.
pub fn thresh_fingerprints(&self) -> (usize, HashSet<bip32::Fingerprint>) {
pub fn thresh_origins(&self) -> (usize, HashSet<(bip32::Fingerprint, bip32::DerivationPath)>) {
match self {
PathInfo::Single(key) => {
let mut fingerprints = HashSet::with_capacity(1);
fingerprints.insert(key_fingerprint(key).expect("Must be a multixpub."));
(1, fingerprints)
let mut origins = HashSet::with_capacity(1);
origins.insert(
key_origin(key)
.expect("Must be a multixpub with an origin.")
.clone(),
);
(1, origins)
}
PathInfo::Multi(k, keys) => (
*k,
keys.iter()
.map(|key| key_fingerprint(key).expect("Must be a multixpub."))
.map(|key| {
key_origin(key)
.expect("Must be a multixpub with an origin.")
.clone()
})
.collect(),
),
}
@ -531,22 +536,34 @@ impl PathInfo {
/// Get the spend information for this descriptor based from the list of all pubkeys that
/// signed the transaction.
pub fn spend_info(
pub fn spend_info<'a>(
&self,
all_pubkeys_signed: impl Iterator<Item = bip32::Fingerprint>,
all_pubkeys_signed: impl Iterator<Item = &'a (bip32::Fingerprint, bip32::DerivationPath)>,
) -> PathSpendInfo {
let mut signed_pubkeys = HashMap::new();
let mut sigs_count = 0;
let (threshold, fingerprints) = self.thresh_fingerprints();
let (threshold, origins) = self.thresh_origins();
// For all existing signatures, pick those that are from one of our pubkeys.
for fingerprint in all_pubkeys_signed {
if fingerprints.contains(&fingerprint) {
for (fg, der_path) in all_pubkeys_signed {
// For all xpubs in the descriptor, we derive at /0/* or /1/*, so the xpub's origin's
// derivation path is the key's one without the last two derivation indexes.
if der_path.len() < 2 {
continue;
}
let parent_der_path: bip32::DerivationPath = der_path[..der_path.len() - 2].into();
let parent_origin = (*fg, parent_der_path);
// Now if the origin of this key without the two final derivation indexes is part of
// the set of our keys, count it as a signature for it. Note it won't mixup keys
// between spending paths, since we can't have duplicate xpubs in the descriptor and
// the (fingerprint, der_path) tuple is a UID for an xpub.
if origins.contains(&parent_origin) {
sigs_count += 1;
if let Some(count) = signed_pubkeys.get_mut(&fingerprint) {
if let Some(count) = signed_pubkeys.get_mut(&parent_origin) {
*count += 1;
} else {
signed_pubkeys.insert(fingerprint, 1);
signed_pubkeys.insert(parent_origin, 1);
}
}
}
@ -594,7 +611,7 @@ pub struct PathSpendInfo {
pub sigs_count: usize,
/// The keys for which a signature was provided and the number (always >=1) of
/// signatures provided for this key.
pub signed_pubkeys: HashMap<bip32::Fingerprint, usize>,
pub signed_pubkeys: HashMap<(bip32::Fingerprint, bip32::DerivationPath), usize>,
}
/// Information about a partial spend of Liana coins
@ -820,7 +837,7 @@ impl MultipathDescriptor {
let pubkeys_signed = psbt_in
.partial_sigs
.iter()
.filter_map(|(pk, _)| psbt_in.bip32_derivation.get(&pk.inner).map(|(fg, _)| *fg));
.filter_map(|(pk, _)| psbt_in.bip32_derivation.get(&pk.inner));
// Determine the structure of the descriptor. Then compute the spend info for the primary
// and recovery paths. Only provide the spend info for the recovery path if it is available
@ -1205,8 +1222,14 @@ mod tests {
// A simple descriptor with 1 keys as primary path and 1 recovery key.
let desc = MultipathDescriptor::from_str("wsh(or_d(pk([f5acc2fd]tpubD6NzVbkrYhZ4YgUx2ZLNt2rLYAMTdYysCRzKoLu2BeSHKvzqPaBDvf17GeBPnExUVPkuBpx4kniP964e2MxyzzazcXLptxLXModSVCVEV1T/<0;1>/*),and_v(v:pkh([8a64f2a9]tpubD6NzVbkrYhZ4WmzFjvQrp7sDa4ECUxTi9oby8K4FZkd3XCBtEdKwUiQyYJaxiJo5y42gyDWEczrFpozEjeLxMPxjf2WtkfcbpUdfvNnozWF/<0;1>/*),older(10))))#d72le4dr").unwrap();
let desc_info = desc.info();
let prim_key_fg = bip32::Fingerprint::from_str("f5acc2fd").unwrap();
let recov_key_fg = bip32::Fingerprint::from_str("8a64f2a9").unwrap();
let prim_key_origin = (
bip32::Fingerprint::from_str("f5acc2fd").unwrap(),
Vec::new().into(),
);
let recov_key_origin: (_, bip32::DerivationPath) = (
bip32::Fingerprint::from_str("8a64f2a9").unwrap(),
Vec::new().into(),
);
// A PSBT with a single input and output, no signature. nSequence is not set to use the
// recovery path.
@ -1246,7 +1269,10 @@ mod tests {
assert_eq!(info.primary_path.sigs_count, 1);
assert!(
info.primary_path.signed_pubkeys.len() == 1
&& info.primary_path.signed_pubkeys.contains_key(&prim_key_fg)
&& info
.primary_path
.signed_pubkeys
.contains_key(&prim_key_origin)
);
assert!(info.recovery_path.is_none());
@ -1258,7 +1284,10 @@ mod tests {
inner: *signed_single_psbt.inputs[0]
.bip32_derivation
.iter()
.find(|(_, (fg, _))| fg == &recov_key_fg)
.find(|(_, (fg, der_path))| {
fg == &recov_key_origin.0
&& der_path[..der_path.len() - 2] == recov_key_origin.1[..]
})
.unwrap()
.0,
};
@ -1285,7 +1314,7 @@ mod tests {
assert_eq!(recov_info.sigs_count, 1);
assert!(
recov_info.signed_pubkeys.len() == 1
&& recov_info.signed_pubkeys.contains_key(&recov_key_fg)
&& recov_info.signed_pubkeys.contains_key(&recov_key_origin)
);
// A PSBT with multiple inputs, all signed for the primary path.
@ -1299,7 +1328,10 @@ mod tests {
assert_eq!(info.primary_path.sigs_count, 1);
assert!(
info.primary_path.signed_pubkeys.len() == 1
&& info.primary_path.signed_pubkeys.contains_key(&prim_key_fg)
&& info
.primary_path
.signed_pubkeys
.contains_key(&prim_key_origin)
);
assert!(info.recovery_path.is_none());
@ -1317,7 +1349,10 @@ mod tests {
assert_eq!(info.primary_path.sigs_count, 1);
assert!(
info.primary_path.signed_pubkeys.len() == 1
&& info.primary_path.signed_pubkeys.contains_key(&prim_key_fg)
&& info
.primary_path
.signed_pubkeys
.contains_key(&prim_key_origin)
);
let recov_info = info.recovery_path.unwrap();
assert_eq!(recov_info.threshold, 1);
@ -1355,7 +1390,10 @@ mod tests {
assert_eq!(info.primary_path.sigs_count, 1);
assert!(
info.primary_path.signed_pubkeys.len() == 1
&& info.primary_path.signed_pubkeys.contains_key(&prim_key_fg)
&& info
.primary_path
.signed_pubkeys
.contains_key(&prim_key_origin)
);
assert!(info.recovery_path.is_none());
@ -1375,7 +1413,12 @@ mod tests {
descriptor::DescriptorPublicKey::from_str("[ffd63c8d/48'/1'/1'/2']tpubDFMs44FD4kFt3M7Z317cFh5tdKEGN8tyQRY6Q5gcSha4NtxZfGmTVRMbsD1bWN469LstXU4aVSARDxrvxFCUjHeegfEY2cLSazMBkNCmDPD/<0;1>/*").unwrap(),
],
)));
// TODO: fix the partial spend info..
let psbt = psbt_from_str("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");
let partial_info = desc.partial_spend_info(&psbt).unwrap();
assert_eq!(partial_info.primary_path.threshold, 2);
assert_eq!(partial_info.primary_path.sigs_count, 1);
assert_eq!(partial_info.primary_path.signed_pubkeys.len(), 1);
assert!(partial_info.recovery_path.is_none());
}
// TODO: test error conditions of deserialization.