WASM: add decryption methods to MerkleNote

ironfish-rust-wasm/src/merkle_note.rs

@@ -2,7 +2,13 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-use crate::{errors::IronfishError, primitives::Scalar, wasm_bindgen_wrapper};
+use crate::{
+    errors::IronfishError,
+    keys::{IncomingViewKey, OutgoingViewKey},
+    note::Note,
+    primitives::Scalar,
+    wasm_bindgen_wrapper,
+};
 use wasm_bindgen::prelude::*;
 
 wasm_bindgen_wrapper! {
@@ -30,6 +36,50 @@ impl MerkleNote {
     pub fn merkle_hash(&self) -> MerkleNoteHash {
         self.0.merkle_hash().into()
     }
+
+    #[wasm_bindgen(js_name = decryptNoteForOwner)]
+    pub fn decrypt_note_for_owner(
+        &self,
+        owner_view_key: &IncomingViewKey,
+    ) -> Result<Note, IronfishError> {
+        self.0
+            .decrypt_note_for_owner(owner_view_key.as_ref())
+            .map(|n| n.into())
+            .map_err(|e| e.into())
+    }
+
+    #[wasm_bindgen(js_name = decryptNoteForOwners)]
+    pub fn decrypt_note_for_owners(&self, owner_view_keys: Vec<IncomingViewKey>) -> Vec<Note> {
+        // The original `decrypt_note_for_owners` returns a `Vec<Result<Note, E>>`. Here instead we
+        // are filtering out all errors. This likely makes this method hard to use in practice,
+        // because the information for mapping between the original owner and the resulting note is
+        // lost. However, returing a `Vec<Result>` or a `Vec<Option>` is currently unsupported in
+        // wasm-bindgen, so offering equivalent functionality requires a new custom type, which can
+        // be implemented at a later date.
+        self.0
+            .decrypt_note_for_owners(
+                owner_view_keys
+                    .into_iter()
+                    .map(|k| k.into())
+                    .collect::<Vec<_>>()
+                    .as_slice(),
+            )
+            .into_iter()
+            .filter_map(Result::ok)
+            .map(|n| n.into())
+            .collect()
+    }
+
+    #[wasm_bindgen(js_name = decryptNoteForSpender)]
+    pub fn decrypt_note_for_spender(
+        &self,
+        spender_key: &OutgoingViewKey,
+    ) -> Result<Note, IronfishError> {
+        self.0
+            .decrypt_note_for_spender(spender_key.as_ref())
+            .map(|n| n.into())
+            .map_err(|e| e.into())
+    }
 }
 
 wasm_bindgen_wrapper! {
@@ -72,10 +122,29 @@ impl MerkleNoteHash {
 
 #[cfg(test)]
 mod tests {
-    use crate::merkle_note::MerkleNoteHash;
+    use crate::{
+        keys::SaplingKey,
+        merkle_note::{MerkleNote, MerkleNoteHash},
+    };
     use hex_literal::hex;
     use wasm_bindgen_test::wasm_bindgen_test;
 
+    // Merkle note copied from one of the fixtures in the `ironfish` NodeJS package
+    const TEST_MERKLE_NOTE_BYTES: [u8; 329] = hex!(
+        "d76e3e7f7f85065f696d6e3587450d8386ae9a62b61aa664eec642afdea715a4b1aaff663825233b351fb068cf\
+        7a9fcba6d17be2f2e56c9848ea1ce44ce0955e0d32fcadc2c462235e7b626bf3b0d6b6dcc261816efebb42b5040\
+        947546e95d898ab93198324e66d612e6975e26ea1f4356b294b6994a18fd76a0b829f8ab94576026110768de2cc\
+        ff9aea405331b128edd905049d286283cc0a0db6302801f8be21b3767ed2ff36b2c7a712f46f89d2e87647e55b4\
+        97225daf24719a713bce9a8522c62f1fb04e6ce67a966da2641d98e9e03a0da925f720040b48acfc30b64e91ca9\
+        f119dcef85ea8bfbc906f203fc1351550995988a3549726f6e2046697368206e6f746520656e6372797074696f6\
+        e206d696e6572206b65793030303030303030303030303030303030303030303030303030303030303030303030\
+        3030303030303030303000"
+    );
+
+    // Key that owns the above note
+    const TEST_SAPLING_KEY_BYTES: [u8; 32] =
+        hex!("2301a28b5c47a79d328e11485647b3da876678028d8312dc40e726e8e118fe1a");
+
     #[test]
     #[wasm_bindgen_test]
     fn combine_hash() {
@@ -93,4 +162,29 @@ mod tests {
             hex!("65fa868a24f39bead19143c23b7c37c6966bec5cf5e60269cb7964d407fe3d47")
         );
     }
+
+    #[test]
+    #[wasm_bindgen_test]
+    fn decrypt_note_for_owner() {
+        let key = SaplingKey::deserialize(TEST_SAPLING_KEY_BYTES.as_slice()).unwrap();
+        let merkle_note = MerkleNote::deserialize(TEST_MERKLE_NOTE_BYTES.as_slice())
+            .expect("deserialization failed");
+        let note = merkle_note
+            .decrypt_note_for_owner(&key.incoming_view_key())
+            .expect("decryption failed");
+
+        assert_eq!(note.value(), 2_000_000_000);
+    }
+
+    #[test]
+    #[wasm_bindgen_test]
+    fn decrypt_note_for_owners() {
+        let key = SaplingKey::deserialize(TEST_SAPLING_KEY_BYTES.as_slice()).unwrap();
+        let merkle_note = MerkleNote::deserialize(TEST_MERKLE_NOTE_BYTES.as_slice())
+            .expect("deserialization failed");
+        let notes = merkle_note.decrypt_note_for_owners(vec![key.incoming_view_key()]);
+
+        assert_eq!(notes.len(), 1);
+        assert_eq!(notes[0].value(), 2_000_000_000);
+    }
 }