Fix htlc witness deserialization (#1138)

* Add prior signatures if they exist

crates/cashu/src/nuts/nut00/mod.rs

@@ -281,12 +281,12 @@ impl PartialOrd for BlindSignature {
 #[serde(untagged)]
 #[cfg_attr(feature = "swagger", derive(utoipa::ToSchema))]
 pub enum Witness {
-    /// P2PK Witness
-    #[serde(with = "serde_p2pk_witness")]
-    P2PKWitness(P2PKWitness),
     /// HTLC Witness
     #[serde(with = "serde_htlc_witness")]
     HTLCWitness(HTLCWitness),
+    /// P2PK Witness
+    #[serde(with = "serde_p2pk_witness")]
+    P2PKWitness(P2PKWitness),
 }
 
 impl From<P2PKWitness> for Witness {
@@ -1042,4 +1042,28 @@ mod tests {
             assert_eq!(method, deserialized);
         }
     }
+
+    #[test]
+    fn test_witness_serialization() {
+        let htlc_witness = HTLCWitness {
+            preimage: "preimage".to_string(),
+            signatures: Some(vec!["sig1".to_string()]),
+        };
+        let witness = Witness::HTLCWitness(htlc_witness);
+
+        let serialized = serde_json::to_string(&witness).unwrap();
+        let deserialized: Witness = serde_json::from_str(&serialized).unwrap();
+
+        assert!(matches!(deserialized, Witness::HTLCWitness(_)));
+
+        let p2pk_witness = P2PKWitness {
+            signatures: vec!["sig1".to_string(), "sig2".to_string()],
+        };
+        let witness = Witness::P2PKWitness(p2pk_witness);
+
+        let serialized = serde_json::to_string(&witness).unwrap();
+        let deserialized: Witness = serde_json::from_str(&serialized).unwrap();
+
+        assert!(matches!(deserialized, Witness::P2PKWitness(_)));
+    }
 }

crates/cashu/src/nuts/nut14/mod.rs

@@ -55,7 +55,7 @@ pub enum Error {
 #[derive(Default, Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
 #[cfg_attr(feature = "swagger", derive(utoipa::ToSchema))]
 pub struct HTLCWitness {
-    /// Primage
+    /// Preimage
     pub preimage: String,
     /// Signatures
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -139,9 +139,15 @@ impl Proof {
     /// Add Preimage
     #[inline]
     pub fn add_preimage(&mut self, preimage: String) {
+        let signatures = self
+            .witness
+            .as_ref()
+            .map(|w| w.signatures())
+            .unwrap_or_default();
+
         self.witness = Some(Witness::HTLCWitness(HTLCWitness {
             preimage,
-            signatures: None,
+            signatures,
         }))
     }
 }