fix: key-rotation related issues in TokenWithRefunds (#7631)

Fixes #7323
Fixes #7324
Fixes #7326

noir-projects/aztec-nr/aztec/src/note/utils.nr

@@ -12,21 +12,21 @@ use dep::protocol_types::{
 };
 use dep::std::{embedded_curve_ops::multi_scalar_mul, hash::from_field_unsafe};
 
-pub fn compute_slotted_note_hash_raw(storage_slot: Field, note_hiding_point: Point) -> Field {
+pub fn compute_slotted_note_hiding_point_raw(storage_slot: Field, note_hiding_point: Point) -> Point {
+    // 1. We derive the storage slot point by multiplying the storage slot with the generator G_slot.
     // We use the unsafe version because the multi_scalar_mul will constrain the scalars.
     let storage_slot_scalar = from_field_unsafe(storage_slot);
     let storage_slot_point = multi_scalar_mul([G_slot], [storage_slot_scalar]);
-    let slotted_note_hiding_point = storage_slot_point + note_hiding_point;
-    let slotted_note_hash = slotted_note_hiding_point.x;
 
-    slotted_note_hash
+    // 2. Then we compute the slotted note hiding point by adding the storage slot point to the note hiding point.
+    storage_slot_point + note_hiding_point
 }
 
 pub fn compute_slotted_note_hash<Note, let N: u32, let M: u32>(note: Note) -> Field where Note: NoteInterface<N, M> {
     let header = note.get_header();
-    let note_hash = note.compute_note_hiding_point();
+    let note_hiding_point = note.compute_note_hiding_point();
 
-    compute_slotted_note_hash_raw(header.storage_slot, note_hash)
+    compute_slotted_note_hiding_point_raw(header.storage_slot, note_hiding_point).x
 }
 
 pub fn compute_siloed_nullifier<Note, let N: u32, let M: u32>(

noir-projects/noir-contracts/contracts/private_fpc_contract/src/main.nr

@@ -9,14 +9,14 @@ contract PrivateFPC {
     #[aztec(storage)]
     struct Storage {
         other_asset: SharedImmutable<AztecAddress>,
-        admin_npk_m_hash: SharedImmutable<Field>
+        admin: SharedImmutable<AztecAddress>,
     }
 
     #[aztec(public)]
     #[aztec(initializer)]
-    fn constructor(other_asset: AztecAddress, admin_npk_m_hash: Field) {
+    fn constructor(other_asset: AztecAddress, admin: AztecAddress) {
         storage.other_asset.initialize(other_asset);
-        storage.admin_npk_m_hash.initialize(admin_npk_m_hash);
+        storage.admin.initialize(admin);
     }
 
     #[aztec(private)]
@@ -32,7 +32,7 @@ contract PrivateFPC {
         emit_randomness_as_unencrypted_log(&mut context, fee_payer_randomness);
 
         TokenWithRefunds::at(asset).setup_refund(
-            storage.admin_npk_m_hash.read_private(),
+            storage.admin.read_private(),
             context.msg_sender(),
             amount,
             user_randomness,