WIP

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

@@ -123,7 +123,25 @@ contract NFT {
         storage.public_owners.at(token_id).write(to);
     }
 
-    // TODO(#8238): Remove ther randomness argument below
+    // We have only public burn flow because the flow is not that common for it to be worth it to clutter
+    // the contract with a private one.
+    #[aztec(public)]
+    fn burn(from: AztecAddress, token_id: Field, nonce: Field) {
+        if (!from.eq(context.msg_sender())) {
+            assert_current_call_valid_authwit_public(&mut context, from);
+        } else {
+            assert(nonce == 0, "invalid nonce");
+        }
+
+        let public_owner = storage.public_owners.at(token_id).read();
+        assert(public_owner.eq(from), "invalid owner");
+
+        storage.nft_exists.at(token_id).write(false);
+        storage.public_owners.at(token_id).write(AztecAddress::zero());
+    }
+
+    // TODO(#8238): Remove ther randomness argument below once we have partial notes delivery (then we can just fetch
+    // the randomness from oracle).
     #[aztec(private)]
     fn prepare_shield(finalizer: AztecAddress, randomness: Field) {
         // We create a partial NFT note with unpopulated/zero token id for msg_sender
@@ -215,7 +233,7 @@ contract NFT {
         let mut options = NoteGetterOptions::new();
         options = options.select(NFTNote::properties().token_id, token_id, Option::none()).set_limit(1);
         let notes = nfts.at(from).pop_notes(options);
-        assert(notes.len() == 1, "NFT not found");
+        assert(notes.len() == 1, "NFT not found when transferring");
 
         let from_ovpk_m = get_current_public_keys(&mut context, from).ovpk_m;
         let to_keys = get_current_public_keys(&mut context, to);
@@ -225,13 +243,25 @@ contract NFT {
     }
 
     #[aztec(private)]
-    fn unshield(from: AztecAddress, to: AztecAddress, amount: Field, nonce: Field) {
+    fn unshield(from: AztecAddress, to: AztecAddress, token_id: Field, nonce: Field) {
         if (!from.eq(context.msg_sender())) {
             assert_current_call_valid_authwit(&mut context, from);
         } else {
             assert(nonce == 0, "invalid nonce");
         }
-        // ...
+
+        let mut options = NoteGetterOptions::new();
+        options = options.select(NFTNote::properties().token_id, token_id, Option::none()).set_limit(1);
+        let notes = storage.private_nfts.at(from).pop_notes(options);
+        assert(notes.len() == 1, "NFT not found when unshielding");
+
+        NFT::at(context.this_address())._finish_unshield(to, token_id).enqueue(&mut context);
+    }
+
+    #[aztec(public)]
+    #[aztec(internal)]
+    fn _finish_unshield(to: AztecAddress, token_id: Field) {
+        storage.public_owners.at(token_id).write(to);
     }
 
     // Returns zero address when the token does not have public owner. Reverts if the token does not exist.

yarn-project/end-to-end/src/e2e_nft.test.ts

@@ -63,7 +63,7 @@ describe('NFT', () => {
     expect(ownerAfterMint).toEqual(user1Wallet.getAddress());
   });
 
-  it('user shields', async () => {
+  it('shields', async () => {
     // In a simple shield flow the finalizer is the user itself (in the uniswap swap to shield flow it would be
     // the uniswap contract)
     const finalizer = user1Wallet.getAddress();
@@ -102,10 +102,37 @@ describe('NFT', () => {
     // console.log('txEffect', txEffect);
   });
 
-  it('user privately sends', async () => {
+  it('privately sends', async () => {
     await nftContractAsUser1.methods
       .transfer_from(user1Wallet.getAddress(), user2Wallet.getAddress(), TOKEN_ID, 0)
       .send()
       .wait();
   });
+
+  it('unshields', async () => {
+    await nftContractAsUser2.methods
+      .unshield(user2Wallet.getAddress(), user2Wallet.getAddress(), TOKEN_ID, 0)
+      .send()
+      .wait();
+
+    const publicOwnerAfter = await nftContractAsUser2.methods.owner_of(TOKEN_ID).simulate();
+    expect(publicOwnerAfter).toEqual(user2Wallet.getAddress());
+  });
+
+  it('publicly sends', async () => {
+    await nftContractAsUser2.methods
+      .transfer_public(user2Wallet.getAddress(), user1Wallet.getAddress(), TOKEN_ID, 0)
+      .send()
+      .wait();
+
+    const publicOwnerAfter = await nftContractAsUser2.methods.owner_of(TOKEN_ID).simulate();
+    expect(publicOwnerAfter).toEqual(user1Wallet.getAddress());
+  });
+
+  it('burns', async () => {
+    await nftContractAsUser1.methods.burn(user1Wallet.getAddress(), TOKEN_ID, 0).send().wait();
+
+    const publicOwnerAfter = await nftContractAsUser1.methods.owner_of(TOKEN_ID).simulate();
+    expect(publicOwnerAfter).toEqual(AztecAddress.ZERO);
+  });
 });