Merge pull request #99 from Foundation-Devices/SFT-6076

SFT-6076: Sort multisig descriptor keys.

Author: mjg-foundation

src/psbt.rs

@@ -19,6 +19,7 @@ use bdk_wallet::bitcoin::{
 };
 use bdk_wallet::descriptor::ExtendedDescriptor;
 use bdk_wallet::keys::{DescriptorPublicKey, SinglePub, SinglePubKey};
+use std::cmp::Ordering;
 use std::collections::{BTreeMap, HashSet};
 use thiserror::Error;
 
@@ -850,3 +851,19 @@ where
         key: SinglePubKey::FullKey(derived_xpub.to_pub().into()),
     })
 }
+
+pub(crate) fn sort_keys(keys: &mut [DescriptorPublicKey]) {
+    fn to_public_key(pk: &DescriptorPublicKey) -> Option<PublicKey> {
+        match pk {
+            DescriptorPublicKey::XPub(xpub) => Some(xpub.xkey.public_key),
+            _ => None,
+        }
+    }
+
+    keys.sort_by(|a, b| {
+        to_public_key(a)
+            .and_then(|a| to_public_key(b).map(|b| (a.serialize(), b.serialize())))
+            .map(|(a, b)| a.cmp(&b))
+            .unwrap_or(Ordering::Equal)
+    });
+}

src/psbt/p2sh.rs

@@ -1,6 +1,6 @@
 use crate::bip32::NgAccountPath;
 use crate::psbt::{
-    Error, OutputKind, PsbtOutput, derive_account_xpub, derive_full_descriptor_pubkey,
+    Error, OutputKind, PsbtOutput, derive_account_xpub, derive_full_descriptor_pubkey, sort_keys,
 };
 use bdk_wallet::bitcoin::bip32::{ChildNumber, DerivationPath, KeySource, Xpriv, Xpub};
 use bdk_wallet::bitcoin::psbt;
@@ -224,6 +224,9 @@ pub fn wsh_multisig_descriptor(
         internal_keys.push(internal_key);
     }
 
+    sort_keys(&mut external_keys);
+    sort_keys(&mut internal_keys);
+
     let external_descriptor =
         ExtendedDescriptor::new_sh_wsh_sortedmulti(usize::from(required_signers), external_keys)
             .unwrap();

src/psbt/p2wsh.rs

@@ -1,5 +1,5 @@
 use crate::bip32::NgAccountPath;
-use crate::psbt::{Error, OutputKind, PsbtOutput};
+use crate::psbt::{Error, OutputKind, PsbtOutput, sort_keys};
 use bdk_wallet::bitcoin::bip32::{ChildNumber, DerivationPath, KeySource, Xpub};
 use bdk_wallet::bitcoin::psbt;
 use bdk_wallet::bitcoin::secp256k1::PublicKey;
@@ -140,6 +140,9 @@ pub fn multisig_descriptor(
         internal_keys.push(internal_key);
     }
 
+    sort_keys(&mut external_keys);
+    sort_keys(&mut internal_keys);
+
     let external_descriptor =
         ExtendedDescriptor::new_wsh_sortedmulti(usize::from(required_signers), external_keys)
             .unwrap();