feat: Allow nullifier proofs in public (#4892)

Allow performing nullifier proofs for the latest block in public.
Required for initialization checks.

noir-projects/aztec-nr/aztec/src/context/interface.nr

@@ -1,6 +1,7 @@
 use dep::protocol_types::{
   abis::function_selector::FunctionSelector,
   address::{AztecAddress, EthAddress},
+  header::Header,
 };
 
 trait ContextInterface {
@@ -12,4 +13,5 @@ trait ContextInterface {
     fn chain_id(self) -> Field;
     fn version(self) -> Field;
     fn selector(self) -> FunctionSelector;
+    fn get_header(self) -> Header;
 }

noir-projects/aztec-nr/aztec/src/context/private_context.nr

@@ -93,6 +93,12 @@ impl ContextInterface for PrivateContext {
         self.inputs.call_context.function_selector
     }
 
+    // Returns the header of a block whose state is used during private execution (not the block the transaction is
+    // included in).
+    pub fn get_header(self) -> Header {
+        self.historical_header
+    }
+
     fn push_new_note_hash(&mut self, note_hash: Field) {
         let side_effect = SideEffect { value: note_hash, counter: self.side_effect_counter };
         self.new_note_hashes.push(side_effect);
@@ -140,12 +146,6 @@ impl PrivateContext {
         false
     }
 
-    // Returns the header of a block whose state is used during private execution (not the block the transaction is
-    // included in).
-    pub fn get_header(self) -> Header {
-        self.historical_header
-    }
-
     // Returns the header of an arbitrary block whose block number is less than or equal to the block number
     // of historical header.
     pub fn get_header_at(self, block_number: u32) -> Header {

noir-projects/aztec-nr/aztec/src/context/public_context.nr

@@ -71,6 +71,10 @@ impl ContextInterface for PublicContext {
         self.inputs.call_context.function_selector
     }
 
+    fn get_header(self) -> Header {
+        self.historical_header
+    }
+
     fn push_new_note_hash(&mut self, note_hash: Field) {
         let side_effect = SideEffect { value: note_hash, counter: self.side_effect_counter };
         self.new_note_hashes.push(side_effect);

noir-projects/aztec-nr/aztec/src/history/nullifier_inclusion.nr

@@ -2,7 +2,7 @@ use dep::std::merkle::compute_merkle_root;
 use dep::protocol_types::header::Header;
 
 use crate::{
-    context::PrivateContext, oracle::get_nullifier_membership_witness::get_nullifier_membership_witness,
+    context::{PrivateContext, ContextInterface}, oracle::get_nullifier_membership_witness::get_nullifier_membership_witness,
     note::{utils::compute_siloed_nullifier, note_interface::NoteInterface}
 };
 
@@ -25,8 +25,8 @@ fn _nullifier_inclusion(nullifier: Field, header: Header) {
     //     was included in the nullifier tree.
 }
 
-pub fn prove_nullifier_inclusion(nullifier: Field, context: PrivateContext) {
-    _nullifier_inclusion(nullifier, context.historical_header);
+pub fn prove_nullifier_inclusion<TContext>(nullifier: Field, context: TContext) where TContext: ContextInterface {
+    _nullifier_inclusion(nullifier, context.get_header());
 }
 
 pub fn prove_nullifier_inclusion_at(

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

@@ -183,6 +183,12 @@ contract InclusionProofs {
         }
     }
 
+    // Proves nullifier existed at latest block
+    #[aztec(public)]
+    fn test_nullifier_inclusion_from_public(nullifier: Field) {
+        prove_nullifier_inclusion(nullifier, context);
+    }
+
     #[aztec(private)]
     fn test_public_unused_value_inclusion(block_number: u32 // The block at which we'll prove that the public value exists
     ) {

yarn-project/end-to-end/src/e2e_inclusion_proofs_contract.test.ts

@@ -228,6 +228,13 @@ describe('e2e_inclusion_proofs_contract', () => {
       await contract.methods.test_nullifier_inclusion(nullifier!, false, 0n).send().wait();
     });
 
+    it('proves existence of a nullifier in public context', async () => {
+      const block = await pxe.getBlock(deploymentBlockNumber);
+      const nullifier = block?.body.txEffects[0].nullifiers[0];
+
+      await contract.methods.test_nullifier_inclusion_from_public(nullifier!).send().wait();
+    });
+
     it('nullifier existence failure case', async () => {
       // Choose random block number between first block and current block number to test archival node
       const blockNumber = await getRandomBlockNumber();

yarn-project/pxe/src/simulator_oracle/index.ts

@@ -176,6 +176,10 @@ export class SimulatorOracle implements DBOracle {
     }
   }
 
+  public async getNullifierMembershipWitnessAtLatestBlock(nullifier: Fr) {
+    return this.getNullifierMembershipWitness(await this.getBlockNumber(), nullifier);
+  }
+
   public getNullifierMembershipWitness(
     blockNumber: number,
     nullifier: Fr,

yarn-project/sequencer-client/src/simulator/public_executor.ts

@@ -3,6 +3,7 @@ import {
   ExtendedContractData,
   L1ToL2MessageSource,
   MerkleTreeId,
+  NullifierMembershipWitness,
   Tx,
   UnencryptedL2Log,
 } from '@aztec/circuit-types';
@@ -14,6 +15,8 @@ import {
   Fr,
   FunctionSelector,
   L1_TO_L2_MSG_TREE_HEIGHT,
+  NULLIFIER_TREE_HEIGHT,
+  NullifierLeafPreimage,
   PublicDataTreeLeafPreimage,
 } from '@aztec/circuits.js';
 import { computePublicDataTreeLeafSlot } from '@aztec/circuits.js/hash';
@@ -217,6 +220,29 @@ export class WorldStatePublicDB implements PublicStateDB {
 export class WorldStateDB implements CommitmentsDB {
   constructor(private db: MerkleTreeOperations, private l1ToL2MessageSource: L1ToL2MessageSource) {}
 
+  public async getNullifierMembershipWitnessAtLatestBlock(
+    nullifier: Fr,
+  ): Promise<NullifierMembershipWitness | undefined> {
+    const index = await this.db.findLeafIndex(MerkleTreeId.NULLIFIER_TREE, nullifier.toBuffer());
+    if (!index) {
+      return undefined;
+    }
+
+    const leafPreimagePromise = this.db.getLeafPreimage(MerkleTreeId.NULLIFIER_TREE, index);
+    const siblingPathPromise = this.db.getSiblingPath<typeof NULLIFIER_TREE_HEIGHT>(
+      MerkleTreeId.NULLIFIER_TREE,
+      BigInt(index),
+    );
+
+    const [leafPreimage, siblingPath] = await Promise.all([leafPreimagePromise, siblingPathPromise]);
+
+    if (!leafPreimage) {
+      return undefined;
+    }
+
+    return new NullifierMembershipWitness(BigInt(index), leafPreimage as NullifierLeafPreimage, siblingPath);
+  }
+
   public async getL1ToL2MembershipWitness(
     entryKey: Fr,
   ): Promise<MessageLoadOracleInputs<typeof L1_TO_L2_MSG_TREE_HEIGHT>> {

yarn-project/simulator/src/public/db.ts

@@ -1,3 +1,4 @@
+import { NullifierMembershipWitness } from '@aztec/circuit-types';
 import { EthAddress, FunctionSelector, L1_TO_L2_MSG_TREE_HEIGHT } from '@aztec/circuits.js';
 import { AztecAddress } from '@aztec/foundation/aztec-address';
 import { Fr } from '@aztec/foundation/fields';
@@ -66,7 +67,7 @@ export interface PublicContractsDB {
   getPortalContractAddress(address: AztecAddress): Promise<EthAddress | undefined>;
 }
 
-/** Database interface for providing access to commitment tree and l1 to l2 message tree (append only data trees). */
+/** Database interface for providing access to commitment tree, l1 to l2 message tree, and nullifier tree. */
 export interface CommitmentsDB {
   /**
    * Gets a confirmed L1 to L2 message for the given entry key.
@@ -89,4 +90,11 @@ export interface CommitmentsDB {
    * @returns - The index of the nullifier. Undefined if it does not exist in the tree.
    */
   getNullifierIndex(nullifier: Fr): Promise<bigint | undefined>;
+
+  /**
+   * Returns a nullifier membership witness for the given nullifier or undefined if not found.
+   * REFACTOR: Same as getL1ToL2MembershipWitness, can be combined with aztec-node method that does almost the same thing.
+   * @param nullifier - Nullifier we're looking for.
+   */
+  getNullifierMembershipWitnessAtLatestBlock(nullifier: Fr): Promise<NullifierMembershipWitness | undefined>;
 }

yarn-project/simulator/src/public/public_execution_context.ts

@@ -1,4 +1,4 @@
-import { FunctionL2Logs, UnencryptedL2Log } from '@aztec/circuit-types';
+import { FunctionL2Logs, NullifierMembershipWitness, UnencryptedL2Log } from '@aztec/circuit-types';
 import { CallContext, FunctionData, FunctionSelector, GlobalVariables, Header } from '@aztec/circuits.js';
 import { AztecAddress } from '@aztec/foundation/aztec-address';
 import { EthAddress } from '@aztec/foundation/eth-address';
@@ -226,4 +226,14 @@ export class PublicExecutionContext extends TypedOracle {
 
     return childExecutionResult.returnValues;
   }
+
+  public async getNullifierMembershipWitness(
+    blockNumber: number,
+    nullifier: Fr,
+  ): Promise<NullifierMembershipWitness | undefined> {
+    if (!this.header.globalVariables.blockNumber.equals(new Fr(blockNumber))) {
+      throw new Error(`Public execution oracle can only access nullifier membership witnesses for the current block`);
+    }
+    return await this.commitmentsDb.getNullifierMembershipWitnessAtLatestBlock(nullifier);
+  }
 }