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Merge #750: descriptors: introduce a helper to prune BIP32 derivation paths

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ea4c4462406f5a1860140ca92bb7fca34e1322e0 descriptor: add a helper which guesses which paths to prune from a PSBT (Antoine Poinsot)
d03e603abbd588d97da81cf0e51d28cbef82f94d descriptors: add a helper to prune BIP32 derivation paths (Antoine Poinsot)

Pull request description:

  Based on #749, this provides clients of the library with a way to prune all the BIP32 derivation paths in a PSBT for keys which are not part of the given spending path.

ACKs for top commit:
  edouardparis:
    utACK ea4c4462406f5a1860140ca92bb7fca34e1322e0

Tree-SHA512: f9f21e12e562a047693066e7b54c2601de01d79071ac40981406a04cf74bfc2da4111b5ea251e3a399a0df95ff6f873da7a7cbb112251100c81bfba171b0a21a
This commit is contained in:
Antoine Poinsot 2023-10-30 13:58:48 +01:00
commit 87555a8da5
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87
src/descriptors/mod.rs
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@ -299,6 +299,62 @@ impl LianaDescriptor {
Ok(spend_info)
}
/// Prune the BIP32 derivations in all the PSBT inputs for all the spending paths but the given
/// one.
pub fn prune_bip32_derivs(&self, mut psbt: Psbt, spending_path: &PathInfo) -> Psbt {
// (Fingerprint, derivation path) pairs uniquely identify a key used in this spending path.
let (_, path_origins) = spending_path.thresh_origins();
// 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
}
/// Prune the BIP32 derivations in all the PSBT inputs for all the spending paths but the
/// latest available one. For instance:
/// - If there is two recovery paths, and the PSBT's first input nSequence isn't set to unlock
/// any of them, prune all but the primary path's bip32 derivations.
/// - If there is two recovery paths, and the PSBT's first input nSequence is set to unlock the
/// first one, prune all but the first recovery path's bip32 derivations.
/// - Etc..
pub fn prune_bip32_derivs_last_avail(&self, psbt: Psbt) -> Result<Psbt, LianaDescError> {
let spend_info = self.partial_spend_info(&psbt)?;
let policy = self.policy();
let path_info = spend_info
.recovery_paths
.iter()
.last()
.map(|(tl, _)| {
policy
.recovery_paths
.get(tl)
.expect("Same timelocks must be keys in both mappings.")
})
.unwrap_or(&policy.primary_path);
Ok(self.prune_bip32_derivs(psbt, path_info))
}
}
impl SinglePathLianaDesc {
@ -1162,5 +1218,36 @@ mod tests {
}
}
#[test]
fn bip32_derivs_pruning() {
// A signet descriptor created using Liana v2.
let desc = LianaDescriptor::from_str("wsh(or_i(and_v(v:thresh(3,pkh([636adf3f/48'/1'/0'/2']tpubDEE9FvWbG4kg4gxDNrALgrWLiHwNMXNs8hk6nXNPw4VHKot16xd2251vwi2M6nsyQTkak5FJNHVHkCcuzmvpSbWHdumX3DxpDm89iTfSBaL/<4;5>/*),a:pkh([172ba1bc/48'/1'/0'/2']tpubDEgTZEAraUrKmnbyKJuXYGFPzNCm82bjMqd2GRy2HKviJ1moLtEZrHoUeG2o6uyWLEGx4yBWpctAmxcBx1b5nrrrBo5LjskRxRMDmwkuKxq/<4;5>/*),a:pkh([903115ef/48'/1'/0'/2']tpubDF2Hqd3HXUn5bDMVa2gssqmdTjQsLm9Vc8CSSJFk4YwQg8PChCZiWopAeQ6ZCEWt21n1W8ApEGxEvtB8uPnWW6EG3fwPAFnFM8US4QmgKvp/<4;5>/*)),older(6)),or_d(multi(3,[636adf3f/48'/1'/0'/2']tpubDEE9FvWbG4kg4gxDNrALgrWLiHwNMXNs8hk6nXNPw4VHKot16xd2251vwi2M6nsyQTkak5FJNHVHkCcuzmvpSbWHdumX3DxpDm89iTfSBaL/<0;1>/*,[172ba1bc/48'/1'/0'/2']tpubDEgTZEAraUrKmnbyKJuXYGFPzNCm82bjMqd2GRy2HKviJ1moLtEZrHoUeG2o6uyWLEGx4yBWpctAmxcBx1b5nrrrBo5LjskRxRMDmwkuKxq/<0;1>/*,[903115ef/48'/1'/0'/2']tpubDF2Hqd3HXUn5bDMVa2gssqmdTjQsLm9Vc8CSSJFk4YwQg8PChCZiWopAeQ6ZCEWt21n1W8ApEGxEvtB8uPnWW6EG3fwPAFnFM8US4QmgKvp/<0;1>/*),and_v(v:thresh(2,pkh([636adf3f/48'/1'/0'/2']tpubDEE9FvWbG4kg4gxDNrALgrWLiHwNMXNs8hk6nXNPw4VHKot16xd2251vwi2M6nsyQTkak5FJNHVHkCcuzmvpSbWHdumX3DxpDm89iTfSBaL/<2;3>/*),a:pkh([172ba1bc/48'/1'/0'/2']tpubDEgTZEAraUrKmnbyKJuXYGFPzNCm82bjMqd2GRy2HKviJ1moLtEZrHoUeG2o6uyWLEGx4yBWpctAmxcBx1b5nrrrBo5LjskRxRMDmwkuKxq/<2;3>/*),a:pkh([903115ef/48'/1'/0'/2']tpubDF2Hqd3HXUn5bDMVa2gssqmdTjQsLm9Vc8CSSJFk4YwQg8PChCZiWopAeQ6ZCEWt21n1W8ApEGxEvtB8uPnWW6EG3fwPAFnFM8US4QmgKvp/<2;3>/*)),older(3)))))#jxya9h7u").unwrap();
// A spend PSBT created using Liana v2.
let psbt = Psbt::from_str("cHNidP8BAFICAAAAAc+3IQFejOVro5Hlwy18au5Jr5mJX+tNMGk0ZE1hydIbAQAAAAD9////ARhzAQAAAAAAFgAUqJZUU7Fqu+bIvxjNw+TAtTwP9HQAAAAAAAEAzQIAAAAAAQEIoAeUdfZj04Ds8EspEK222TJdDNy1WZb/Mg1PJbQekwAAAAAA/f///wKQCQQAAAAAACJRIPJojBgnDc9oUS5lDNx/YJznYR2NPQue7h/d+o5Z+2FQoIYBAAAAAAAiACDZrCBvscZpg+S+IaoZBJjyKDdrNS3oXPaF17DNaB+4mAFAe9yuRS3Vn8A5NUglhwiX7vN0wpQ0Q43ClWtJRnC2HJ66h5HYJ/p8xHgHOhRDUWRzcXLLGl+brc5dW+k0OvIZEyuLAgABASughgEAAAAAACIAINmsIG+xxmmD5L4hqhkEmPIoN2s1Lehc9oXXsM1oH7iYAQX9GQFjdqkU2zK+b9oTL/KfnOSYtq3wmtf4qP6IrGt2qRTSNOD0U7fuHdAnKchIf8GmUO904YisbJNrdqkUE5TQk5mdyYtviaGAsIiOgc4y6wGIrGyTU4hWsmdTIQOirPI1KXBtP2Tg2FQxSo4BjFBTf+dCKtZwDQt056slgCEDDHE7Hpxq++JsjZdbfwsPiA6pmq0dV00tR3hc2sus8KkhA2nPUthIMe1SeFegiZEKZF69yJerP1RFVlyu66C5lOVVU65zZHapFEUmCTccyLJXczvUfPUOCXr7CN0uiKxrdqkUeJmVqUt1Q4aFREOUWKX9U/SuZZ2IrGyTa3apFBDmKn40ceTWVbwxRI21c2qji1tOiKxsk1KIU7JoaCIGAjCZLg7xtlG43xEvns0TRd5gHpPrZWzAaYjo3lheMw/hHJAxFe8wAACAAQAAgAAAAIACAACAAgAAAAgAAAAiBgI0Y2/HRNvXA3niUE3RvrzQcCDiJ4F6vVog0uIanRUWHhwXK6G8MAAAgAEAAIAAAACAAgAAgAIAAAAIAAAAIgYCQKZf/IBUWv4F4mGVTv5PlqCceXFtlhfOgW0kIAPI74scFyuhvDAAAIABAACAAAAAgAIAAIAEAAAACAAAACIGAkDfArY5kwHyHvKllcCMhQLErtDmT/A13vABH8PBQ6yIHGNq3z8wAACAAQAAgAAAAIACAACABAAAAAgAAAAiBgLp9dq4ku0u9UKpIRasIb5QEPgPkDcxdcSXYBfW7mUcqByQMRXvMAAAgAEAAIAAAACAAgAAgAQAAAAIAAAAIgYDDHE7Hpxq++JsjZdbfwsPiA6pmq0dV00tR3hc2sus8KkcFyuhvDAAAIABAACAAAAAgAIAAIAAAAAACAAAACIGA0SIq7IkQJYb7brFx54mPzwUl/DzCGja0pdwFFckfm6WHGNq3z8wAACAAQAAgAAAAIACAACAAgAAAAgAAAAiBgNpz1LYSDHtUnhXoImRCmRevciXqz9URVZcruuguZTlVRyQMRXvMAAAgAEAAIAAAACAAgAAgAAAAAAIAAAAIgYDoqzyNSlwbT9k4NhUMUqOAYxQU3/nQirWcA0LdOerJYAcY2rfPzAAAIABAACAAAAAgAIAAIAAAAAACAAAAAAA").unwrap();
// The above PSBT with BIP32 derivs manually pruned using bip174.org.
let pruned_psbt = Psbt::from_str("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").unwrap();
// Before pruning it the PSBT has an entry per key in the descriptor.
assert_eq!(psbt.inputs[0].bip32_derivation.len(), 9);
// Prune the PSBT. It should result in the same as when manually pruned using bip174.org.
assert_ne!(psbt, pruned_psbt);
let prim_path_info = desc.policy().primary_path;
let psbt = desc.prune_bip32_derivs(psbt, &prim_path_info);
assert_eq!(psbt, pruned_psbt);
// After pruning it the PSBT only has an entry per key in the primary path.
assert_eq!(psbt.inputs[0].bip32_derivation.len(), 3);
// Same but with recovery PSBTs.
let psbt = Psbt::from_str("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").unwrap();
let pruned_psbt = Psbt::from_str("cHNidP8BAFICAAAAAc+3IQFejOVro5Hlwy18au5Jr5mJX+tNMGk0ZE1hydIbAQAAAAADAAAAAbSFAQAAAAAAFgAUBSY69rqtGQLCmhuT29Ep4ZO5Sk8AAAAAAAEAzQIAAAAAAQEIoAeUdfZj04Ds8EspEK222TJdDNy1WZb/Mg1PJbQekwAAAAAA/f///wKQCQQAAAAAACJRIPJojBgnDc9oUS5lDNx/YJznYR2NPQue7h/d+o5Z+2FQoIYBAAAAAAAiACDZrCBvscZpg+S+IaoZBJjyKDdrNS3oXPaF17DNaB+4mAFAe9yuRS3Vn8A5NUglhwiX7vN0wpQ0Q43ClWtJRnC2HJ66h5HYJ/p8xHgHOhRDUWRzcXLLGl+brc5dW+k0OvIZEyuLAgABASughgEAAAAAACIAINmsIG+xxmmD5L4hqhkEmPIoN2s1Lehc9oXXsM1oH7iYAQX9GQFjdqkU2zK+b9oTL/KfnOSYtq3wmtf4qP6IrGt2qRTSNOD0U7fuHdAnKchIf8GmUO904YisbJNrdqkUE5TQk5mdyYtviaGAsIiOgc4y6wGIrGyTU4hWsmdTIQOirPI1KXBtP2Tg2FQxSo4BjFBTf+dCKtZwDQt056slgCEDDHE7Hpxq++JsjZdbfwsPiA6pmq0dV00tR3hc2sus8KkhA2nPUthIMe1SeFegiZEKZF69yJerP1RFVlyu66C5lOVVU65zZHapFEUmCTccyLJXczvUfPUOCXr7CN0uiKxrdqkUeJmVqUt1Q4aFREOUWKX9U/SuZZ2IrGyTa3apFBDmKn40ceTWVbwxRI21c2qji1tOiKxsk1KIU7JoaCIGAjCZLg7xtlG43xEvns0TRd5gHpPrZWzAaYjo3lheMw/hHJAxFe8wAACAAQAAgAAAAIACAACAAgAAAAgAAAAiBgI0Y2/HRNvXA3niUE3RvrzQcCDiJ4F6vVog0uIanRUWHhwXK6G8MAAAgAEAAIAAAACAAgAAgAIAAAAIAAAAIgYDRIirsiRAlhvtusXHniY/PBSX8PMIaNrSl3AUVyR+bpYcY2rfPzAAAIABAACAAAAAgAIAAIACAAAACAAAAAAA").unwrap();
assert_ne!(psbt, pruned_psbt);
assert_eq!(psbt.inputs[0].bip32_derivation.len(), 9);
let psbt = desc.prune_bip32_derivs_last_avail(psbt).unwrap();
assert_eq!(psbt.inputs[0].bip32_derivation.len(), 3);
assert_eq!(psbt, pruned_psbt);
}
// TODO: test error conditions of deserialization.
}