fix(keys): return secret bytes for single descriptor keys

Author: reez

bdk-ffi/src/keys.rs

@@ -266,15 +266,17 @@ impl DescriptorSecretKey {
     pub fn secret_bytes(&self) -> Vec<u8> {
         let inner = &self.0;
         let secret_bytes: Vec<u8> = match inner {
-            BdkDescriptorSecretKey::Single(_) => {
-                unreachable!()
+            BdkDescriptorSecretKey::Single(single_key) => {
+                single_key.key.inner.secret_bytes().to_vec()
             }
             BdkDescriptorSecretKey::XPrv(descriptor_x_key) => {
                 descriptor_x_key.xkey.private_key.secret_bytes().to_vec()
             }
-            BdkDescriptorSecretKey::MultiXPrv(_) => {
-                unreachable!()
-            }
+            BdkDescriptorSecretKey::MultiXPrv(descriptor_multi_x_key) => descriptor_multi_x_key
+                .xkey
+                .private_key
+                .secret_bytes()
+                .to_vec(),
         };
 
         secret_bytes

bdk-ffi/src/tests/keys.rs

@@ -2,6 +2,7 @@ use crate::bitcoin::NetworkKind;
 use crate::error::DescriptorKeyError;
 use crate::keys::{DerivationPath, DescriptorPublicKey, DescriptorSecretKey, Mnemonic};
 use crate::types::WildcardType;
+use bdk_wallet::bitcoin::PrivateKey as BdkPrivateKey;
 use std::sync::Arc;
 
 fn get_inner() -> DescriptorSecretKey {
@@ -93,6 +94,23 @@ fn test_from_str_inner() {
     assert!(DescriptorSecretKey::from_string(key0.to_string()).is_err());
 }
 
+#[test]
+fn test_secret_bytes_from_single_and_multipath_keys() {
+    let wif = "L2wTu6hQrnDMiFNWA5na6jB12ErGQqtXwqpSL7aWquJaZG8Ai3ch";
+    let single_key = DescriptorSecretKey::from_string(wif.to_string()).unwrap();
+    let expected_single_bytes = BdkPrivateKey::from_wif(wif)
+        .unwrap()
+        .inner
+        .secret_bytes()
+        .to_vec();
+    assert_eq!(single_key.secret_bytes(), expected_single_bytes);
+
+    let base_xprv = "tprv8ZgxMBicQKsPcwcD4gSnMti126ZiETsuX7qwrtMypr6FBwAP65puFn4v6c3jrN9VwtMRMph6nyT63NrfUL4C3nBzPcduzVSuHD7zbX2JKVc";
+    let multipath_key = DescriptorSecretKey::from_string(format!("{base_xprv}/<0;1>/*")).unwrap();
+    let base_key = DescriptorSecretKey::from_string(base_xprv.to_string()).unwrap();
+    assert_eq!(multipath_key.secret_bytes(), base_key.secret_bytes());
+}
+
 #[test]
 fn test_derive_and_extend_inner() {
     let master_dsk = get_inner();