feat: token private mint optimization (#9606)

Impl. of token `finalize_mint_to_private`

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

@@ -256,7 +256,7 @@ contract NFT {
     fn _finalize_transfer_to_private(
         from: AztecAddress,
         token_id: Field,
-        note_transient_storage_slot: Field,
+        hiding_point_slot: Field,
         context: &mut PublicContext,
         storage: Storage<&mut PublicContext>,
     ) {
@@ -268,7 +268,7 @@ contract NFT {
 
         // Finalize the partial note with the `token_id`
         let finalization_payload =
-            NFTNote::finalization_payload().new(context, note_transient_storage_slot, token_id);
+            NFTNote::finalization_payload().new(context, hiding_point_slot, token_id);
 
         // At last we emit the note hash and the final log
         finalization_payload.emit();

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

@@ -158,7 +158,7 @@ contract TokenBridge {
     #[public]
     #[internal]
     fn _call_mint_on_token(amount: Field, secret_hash: Field) {
-        Token::at(storage.token.read()).mint_private(amount, secret_hash).call(&mut context);
+        Token::at(storage.token.read()).mint_private_old(amount, secret_hash).call(&mut context);
     }
     // docs:end:call_mint_on_token
 

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

@@ -208,8 +208,9 @@ contract Token {
     }
     // docs:end:mint_public
     // docs:start:mint_private
+    // TODO(benesjan): To be nuked in a followup PR.
     #[public]
-    fn mint_private(amount: Field, secret_hash: Field) {
+    fn mint_private_old(amount: Field, secret_hash: Field) {
         assert(storage.minters.at(context.msg_sender()).read(), "caller is not minter");
         let pending_shields = storage.pending_shields;
         let mut note = TransparentNote::new(amount, secret_hash);
@@ -485,13 +486,15 @@ contract Token {
     // Transfers token `amount` from public balance of message sender to a private balance of `to`.
     #[private]
     fn transfer_to_private(to: AztecAddress, amount: Field) {
+        // We check the minter permissions in the enqueued call as that allows us to avoid the need for `SharedMutable`
+        // which is less efficient.
         let from = context.msg_sender();
         let token = Token::at(context.this_address());
 
         // We prepare the transfer.
         let hiding_point_slot = _prepare_transfer_to_private(to, &mut context, storage);
 
-        // At last we finalize the transfer. Usafe of the `unsafe` method here is safe because we set the `from`
+        // At last we finalize the transfer. Usage of the `unsafe` method here is safe because we set the `from`
         // function argument to a message sender, guaranteeing that he can transfer only his own tokens.
         token._finalize_transfer_to_private_unsafe(from, amount, hiding_point_slot).enqueue(
             &mut context,
@@ -578,7 +581,7 @@ contract Token {
     fn _finalize_transfer_to_private(
         from: AztecAddress,
         amount: Field,
-        note_transient_storage_slot: Field,
+        hiding_point_slot: Field,
         context: &mut PublicContext,
         storage: Storage<&mut PublicContext>,
     ) {
@@ -591,7 +594,70 @@ contract Token {
 
         // Then we finalize the partial note with the `amount`
         let finalization_payload =
-            UintNote::finalization_payload().new(context, note_transient_storage_slot, amount);
+            UintNote::finalization_payload().new(context, hiding_point_slot, amount);
+
+        // At last we emit the note hash and the final log
+        finalization_payload.emit();
+    }
+
+    /// Mints token `amount` to a private balance of `to`. Message sender has to have minter permissions (checked
+    /// in the enqueud call).
+    #[private]
+    fn mint_to_private(to: AztecAddress, amount: Field) {
+        let from = context.msg_sender();
+        let token = Token::at(context.this_address());
+
+        // We prepare the transfer.
+        let hiding_point_slot = _prepare_transfer_to_private(to, &mut context, storage);
+
+        // At last we finalize the mint. Usage of the `unsafe` method here is safe because we set the `from`
+        // function argument to a message sender, guaranteeing that only a message sender with minter permissions
+        // can successfully execute the function.
+        token._finalize_mint_to_private_unsafe(from, amount, hiding_point_slot).enqueue(&mut context);
+    }
+
+    /// Finalizes a mint of token `amount` to a private balance of `to`. The mint must be prepared by calling
+    /// `prepare_transfer_to_private` first and the resulting
+    /// `hiding_point_slot` must be passed as an argument to this function.
+    ///
+    /// Note: This function is only an optimization as it could be replaced by a combination of `mint_public`
+    /// and `finalize_transfer_to_private`. It is however used very commonly so it makes sense to optimize it
+    /// (e.g. used during token bridging, in AMM liquidity token etc.).
+    #[public]
+    fn finalize_mint_to_private(amount: Field, hiding_point_slot: Field) {
+        assert(storage.minters.at(context.msg_sender()).read(), "caller is not minter");
+
+        _finalize_mint_to_private(amount, hiding_point_slot, &mut context, storage);
+    }
+
+    #[public]
+    #[internal]
+    fn _finalize_mint_to_private_unsafe(
+        from: AztecAddress,
+        amount: Field,
+        hiding_point_slot: Field,
+    ) {
+        // We check the minter permissions as it was not done in `mint_to_private` function.
+        assert(storage.minters.at(from).read(), "caller is not minter");
+        _finalize_mint_to_private(amount, hiding_point_slot, &mut context, storage);
+    }
+
+    #[contract_library_method]
+    fn _finalize_mint_to_private(
+        amount: Field,
+        hiding_point_slot: Field,
+        context: &mut PublicContext,
+        storage: Storage<&mut PublicContext>,
+    ) {
+        let amount = U128::from_integer(amount);
+
+        // First we increase the total supply by the `amount`
+        let supply = storage.total_supply.read().add(amount);
+        storage.total_supply.write(supply);
+
+        // Then we finalize the partial note with the `amount`
+        let finalization_payload =
+            UintNote::finalization_payload().new(context, hiding_point_slot, amount);
 
         // At last we emit the note hash and the final log
         finalization_payload.emit();

yarn-project/aztec/src/examples/token.ts

@@ -1,5 +1,5 @@
 import { getSingleKeyAccount } from '@aztec/accounts/single_key';
-import { type AccountWallet, BatchCall, Fr, createPXEClient } from '@aztec/aztec.js';
+import { type AccountWallet, Fr, createPXEClient } from '@aztec/aztec.js';
 import { createDebugLogger } from '@aztec/foundation/log';
 import { TokenContract } from '@aztec/noir-contracts.js/Token';
 
@@ -41,15 +41,7 @@ async function main() {
 
   // Mint tokens to Alice
   logger.info(`Minting ${ALICE_MINT_BALANCE} more coins to Alice...`);
-
-  // We don't have the functionality to mint to private so we mint to the Alice's address in public and transfer
-  // the tokens to private. We use BatchCall to speed the process up.
-  await new BatchCall(aliceWallet, [
-    token.methods.mint_public(aliceWallet.getAddress(), ALICE_MINT_BALANCE).request(),
-    token.methods.transfer_to_private(aliceWallet.getAddress(), ALICE_MINT_BALANCE).request(),
-  ])
-    .send()
-    .wait();
+  await tokenAlice.methods.mint_to_private(aliceWallet.getAddress(), ALICE_MINT_BALANCE).send().wait();
 
   logger.info(`${ALICE_MINT_BALANCE} tokens were successfully minted by Alice and transferred to private`);
 

yarn-project/end-to-end/src/fixtures/token_utils.ts

@@ -1,4 +1,4 @@
-import { type AztecAddress, BatchCall, type DebugLogger, type Wallet, retryUntil } from '@aztec/aztec.js';
+import { type AztecAddress, type DebugLogger, type Wallet, retryUntil } from '@aztec/aztec.js';
 import { TokenContract } from '@aztec/noir-contracts.js';
 
 export async function deployToken(adminWallet: Wallet, initialAdminBalance: bigint, logger: DebugLogger) {
@@ -23,14 +23,8 @@ export async function mintTokensToPrivate(
   recipient: AztecAddress,
   amount: bigint,
 ) {
-  // We don't have the functionality to mint to private so we mint to the minter address in public and transfer
-  // the tokens to the recipient in private. We use BatchCall to speed the process up.
-  await new BatchCall(minterWallet, [
-    token.methods.mint_public(minterWallet.getAddress(), amount).request(),
-    token.methods.transfer_to_private(recipient, amount).request(),
-  ])
-    .send()
-    .wait();
+  const tokenAsMinter = await TokenContract.at(token.address, minterWallet);
+  await tokenAsMinter.methods.mint_to_private(recipient, amount).send().wait();
 }
 
 const awaitUserSynchronized = async (wallet: Wallet, owner: AztecAddress) => {

yarn-project/end-to-end/src/guides/writing_an_account_contract.test.ts

@@ -3,7 +3,6 @@ import {
   AccountManager,
   AuthWitness,
   type AuthWitnessProvider,
-  BatchCall,
   type CompleteAddress,
   Fr,
   GrumpkinScalar,
@@ -64,15 +63,8 @@ describe('guides/writing_an_account_contract', () => {
     const token = await TokenContract.deploy(wallet, address, 'TokenName', 'TokenSymbol', 18).send().deployed();
     logger.info(`Deployed token contract at ${token.address}`);
 
-    // We don't have the functionality to mint to private so we mint to the minter address in public and transfer
-    // the tokens to the recipient in private. We use BatchCall to speed the process up.
     const mintAmount = 50n;
-    await new BatchCall(wallet, [
-      token.methods.mint_public(address, mintAmount).request(),
-      token.methods.transfer_to_private(address, mintAmount).request(),
-    ])
-      .send()
-      .wait();
+    await token.methods.mint_to_private(address, mintAmount).send().wait();
 
     const balance = await token.methods.balance_of_private(address).simulate();
     logger.info(`Balance of wallet is now ${balance}`);

yarn-project/end-to-end/src/sample-dapp/index.mjs

@@ -1,6 +1,6 @@
 // docs:start:imports
 import { getInitialTestAccountsWallets } from '@aztec/accounts/testing';
-import { BatchCall, createPXEClient, waitForPXE } from '@aztec/aztec.js';
+import { createPXEClient, waitForPXE } from '@aztec/aztec.js';
 import { fileURLToPath } from '@aztec/foundation/url';
 
 import { getToken } from './contracts.mjs';
@@ -38,15 +38,9 @@ async function mintPrivateFunds(pxe) {
 
   await showPrivateBalances(pxe);
 
+  // We mint tokens to the owner
   const mintAmount = 20n;
-  // We don't have the functionality to mint to private so we mint to the owner address in public and transfer
-  // the tokens to the recipient in private. We use BatchCall to speed the process up.
-  await new BatchCall(ownerWallet, [
-    token.methods.mint_public(ownerWallet.getAddress(), mintAmount).request(),
-    token.methods.transfer_to_private(ownerWallet.getAddress(), mintAmount).request(),
-  ])
-    .send()
-    .wait();
+  await token.methods.mint_to_private(ownerWallet.getAddress(), mintAmount).send().wait();
 
   await showPrivateBalances(pxe);
 }

yarn-project/end-to-end/src/shared/browser.ts

@@ -251,9 +251,8 @@ export const browserTestSuite = (
 
           console.log(`Contract Deployed: ${token.address}`);
 
-          // We don't use the `mintTokensToPrivate` util as it is not available here
-          await token.methods.mint_public(owner.getAddress(), initialBalance).send().wait();
-          await token.methods.transfer_to_private(owner.getAddress(), initialBalance).send().wait();
+          // We mint tokens to the owner
+          await token.methods.mint_to_private(owner.getAddress(), initialBalance).send().wait();
 
           return [txHash.toString(), token.address.toString()];
         },

yarn-project/protocol-contracts/src/protocol_contract_data.ts

@@ -50,14 +50,14 @@ export const ProtocolContractAddress: Record<ProtocolContractName, AztecAddress>
 };
 
 export const ProtocolContractLeaf = {
-  AuthRegistry: Fr.fromString('0x16f00633c07cb18f29a819d16a8b5140dea24787ca2a030dc54379a8e6896e3e'),
+  AuthRegistry: Fr.fromString('0x2c8f0ae77bbed1244767430f7bf1badf98219c40a1dfc1bba1409caf1a9a01cd'),
   ContractInstanceDeployer: Fr.fromString('0x04a661c9d4d295fc485a7e0f3de40c09b35366343bce8ad229106a8ef4076fe5'),
   ContractClassRegisterer: Fr.fromString('0x147ba3294403576dbad10f86d3ffd4eb83fb230ffbcd5c8b153dd02942d0611f'),
   MultiCallEntrypoint: Fr.fromString('0x154b701b41d6cf6da7204fef36b2ee9578b449d21b3792a9287bf45eba48fd26'),
-  FeeJuice: Fr.fromString('0x2422b0101aba5f5050e8c086a6bdd62b185b188acfba58c77b0016769b96efd6'),
-  Router: Fr.fromString('0x1cedd0ce59239cb4d55408257d8942bdbd1ac6f0ddab9980157255391dbaa596'),
+  FeeJuice: Fr.fromString('0x14c807b45f74c73f4b7c7aa85162fc1ae78fafa81ece6c22426fec928edd9471'),
+  Router: Fr.fromString('0x2cf76c7258a26c77ec56a5b4903996b1e0a21313f78e166f408e955393144665'),
 };
 
 export const protocolContractTreeRoot = Fr.fromString(
-  '0x21fb5ab0a0a9b4f282d47d379ec7b5fdf59457a19a593c17f7c29954e1e88dec',
+  '0x27d6a49f48a8f07db1170672df19cec71fcb71d97588503150628483943e2a14',
 );