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descriptors: encapsulate key matching logic

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It will be useful when we introduce Taproot support in the next commit.
This commit is contained in:
Antoine Poinsot 2024-03-12 15:28:40 +01:00
parent 85fdc40366
commit c897d41965
No known key found for this signature in database
GPG Key ID: E13FC145CD3F4304
1 changed files with 31 additions and 19 deletions
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50
src/descriptors/mod.rs
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@ -8,7 +8,11 @@ use miniscript::{
descriptor, translate_hash_clone, ForEachKey, TranslatePk, Translator,
};
use std::{collections::BTreeMap, convert::TryInto, error, fmt, str};
use std::{
collections::{BTreeMap, HashMap, HashSet},
convert::TryInto,
error, fmt, str,
};
use serde::{Deserialize, Serialize};
@ -49,6 +53,29 @@ impl From<LianaPolicyError> for LianaDescError {
}
}
// Whether the key identified by its fingerprint+derivation path was derived from one of the xpubs
// for this spending path.
fn key_is_for_path(
path_origins: &HashMap<bip32::Fingerprint, HashSet<bip32::DerivationPath>>,
fg: &bip32::Fingerprint,
der_path: &bip32::DerivationPath,
) -> bool {
// Does it come from a signer used in this spending path?
if let Some(der_paths) = path_origins.get(fg) {
// Get the derivation path from the master fingerprint to the parent used to
// derive this key, in order to check whether it's part of the derivation paths
// used in this spending path (only checking the fingerprint isn't sufficient
// as a single signer may be used in more than one spending path).
// NOTE: this assumes there is only one derivation step after the key used in
// the policy. This is fine, because the keys in the policy are normalized (so
// the derivation path up to the wildcard is part of the origin).
if let Some((_, der_path_no_wildcard)) = der_path[..].split_last() {
return der_paths.contains(&der_path_no_wildcard.into());
}
}
false
}
/// An [SinglePathLianaDesc] that contains multipath keys for (and only for) the receive keychain
/// and the change keychain.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
@ -378,24 +405,9 @@ impl LianaDescriptor {
// Go through all the PSBT inputs and drop the BIP32 derivations for keys that are not from
// this spending path.
for psbt_in in psbt.inputs.iter_mut() {
psbt_in.bip32_derivation.retain(|_, (fg, der_path)| {
// Does it come from a signer used in this spending path?
if let Some(der_paths) = path_origins.get(fg) {
// Get the derivation path from the master fingerprint to the parent used to
// derive this key, in order to check whether it's part of the derivation paths
// used in this spending path (only checking the fingerprint isn't sufficient
// as a single signer may be used in more than one spending path).
// NOTE: this assumes there is only one derivation step after the key used in
// the policy. This is fine, because the keys in the policy are normalized (so
// the derivation path up to the wildcard is part of the origin).
if let Some((_, der_path_no_wildcard)) = der_path[..].split_last() {
if der_paths.contains(&der_path_no_wildcard.into()) {
return true;
}
}
}
false
});
psbt_in
.bip32_derivation
.retain(|_, (fg, der_path)| key_is_for_path(&path_origins, fg, der_path));
}
psbt