feat: removing superfluous call to MSM (#7708)

noir-projects/aztec-nr/aztec/src/generators.nr

@@ -7,14 +7,6 @@ global Ga3 = Point { x: 0x0edb1e293c3ce91bfc04e3ceaa50d2c541fa9d091c72eb403efb1c
 // If you change this update `G_SLOT` in `yarn-project/simulator/src/client/test_utils.ts` as well
 global G_slot = Point { x: 0x041223147b680850dc82e8a55a952d4df20256fe0593d949a9541ca00f0abf15, y: 0x0a8c72e60d0e60f5d804549d48f3044d06140b98ed717a9b532af630c1530791, is_infinite: false };
 
-// TODO(#7551): nuke this func - is only temporarily used in note_interface.rs before we get some AVM compatible
-// hash func hashing to a point
-pub fn field_to_point(slot_preimage: Field) -> Point {
-    // We use the unsafe version because the multi_scalar_mul will constrain the scalars.
-    let slot_preimage_scalar = dep::std::hash::from_field_unsafe(slot_preimage);
-    dep::std::embedded_curve_ops::multi_scalar_mul([G_slot], [slot_preimage_scalar])
-}
-
 mod test {
     use crate::generators::{Ga1, Ga2, Ga3, G_slot};
     use dep::protocol_types::point::Point;

noir-projects/aztec-nr/aztec/src/hash.nr

@@ -4,8 +4,9 @@ use dep::protocol_types::{
     GENERATOR_INDEX__SECRET_HASH, GENERATOR_INDEX__MESSAGE_NULLIFIER, ARGS_HASH_CHUNK_COUNT,
     GENERATOR_INDEX__FUNCTION_ARGS, ARGS_HASH_CHUNK_LENGTH, MAX_ARGS_LENGTH
 },
-    traits::Hash, hash::{pedersen_hash, compute_siloed_nullifier, sha256_to_field}
+    traits::Hash, hash::{pedersen_hash, compute_siloed_nullifier, sha256_to_field, pedersen_commitment}
 };
+// Note: pedersen_commitment is used only as a re-export here
 use crate::oracle::logs_traits::{LensForEncryptedLog, ToBytesForUnencryptedLog};
 
 pub fn compute_secret_hash(secret: Field) -> Field {

noir-projects/noir-contracts/contracts/token_contract/src/types/token_note.nr

@@ -5,6 +5,13 @@ use dep::aztec::{
     keys::getters::get_nsk_app
 };
 
+// TODO(#7738): Nuke the following imports
+use dep::aztec::{
+    generators::{Ga1 as G_amt, Ga2 as G_npk, Ga3 as G_rnd},
+    protocol_types::{point::Point, scalar::Scalar}
+};
+use dep::std::{embedded_curve_ops::multi_scalar_mul, hash::from_field_unsafe};
+
 trait OwnedNote {
     fn new(amount: U128, owner_npk_m_hash: Field) -> Self;
     fn get_amount(self) -> U128;
@@ -48,6 +55,21 @@ impl NoteInterface<TOKEN_NOTE_LEN, TOKEN_NOTE_BYTES_LEN> for TokenNote {
         ]);
         (note_hash_for_nullify, nullifier)
     }
+
+    // TODO(#7738): Nuke this function and have it auto-generated by macros
+    fn compute_note_hiding_point(self) -> Point {
+        let npk_m_hash_scalar = from_field_unsafe(self.npk_m_hash);
+        let randomness_scalar = from_field_unsafe(self.randomness);
+        multi_scalar_mul(
+            [G_amt, G_npk, G_rnd],
+            [Scalar {
+                lo: self.amount.to_integer(),
+                hi: 0
+            },
+            npk_m_hash_scalar,
+            randomness_scalar]
+        )
+    }
 }
 
 impl OwnedNote for TokenNote {

noir-projects/noir-protocol-circuits/crates/types/src/hash.nr

@@ -12,12 +12,11 @@ use crate::{
 },
     merkle_tree::root::root_from_sibling_path, messaging::l2_to_l1_message::ScopedL2ToL1Message,
     recursion::verification_key::VerificationKey, traits::is_empty,
-    utils::field::field_from_bytes_32_trunc
+    utils::field::field_from_bytes_32_trunc, point::Point
 };
-use std::hash::{pedersen_hash_with_separator, sha256};
 
 pub fn sha256_to_field<let N: u32>(bytes_to_hash: [u8; N]) -> Field {
-    let sha256_hashed = sha256(bytes_to_hash);
+    let sha256_hashed = std::hash::sha256(bytes_to_hash);
     let hash_in_a_field = field_from_bytes_32_trunc(sha256_hashed);
 
     hash_in_a_field
@@ -256,6 +255,10 @@ pub fn poseidon2_hash<let N: u32>(inputs: [Field; N]) -> Field {
     std::hash::poseidon2::Poseidon2::hash(inputs, N)
 }
 
+pub fn pedersen_commitment<let N: u32>(inputs: [Field; N], hash_index: u32) -> Point {
+    std::hash::pedersen_commitment_with_separator(inputs, hash_index)
+}
+
 #[test]
 fn smoke_sha256_to_field() {
     let full_buffer = [
@@ -273,7 +276,7 @@ fn smoke_sha256_to_field() {
     assert(result == 0x448ebbc9e1a31220a2f3830c18eef61b9bd070e5084b7fa2a359fe729184c7);
 
     // to show correctness of the current ver (truncate one byte) vs old ver (mod full bytes):
-    let result_bytes = sha256(full_buffer);
+    let result_bytes = std::hash::sha256(full_buffer);
     let truncated_field = crate::utils::field::field_from_bytes_32_trunc(result_bytes);
     assert(truncated_field == result);
     let mod_res = result + (result_bytes[31] as Field);

noir/noir-repo/aztec_macros/src/transforms/note_interface.rs

@@ -503,14 +503,10 @@ fn generate_compute_note_hiding_point(
     note_type: &String,
     impl_span: Option<Span>,
 ) -> Result<NoirFunction, AztecMacroError> {
-    // TODO(#7551): Replace the pedersen hash with something that returns a point directly to avoid
-    // the superfluous call to field_to_point(...). I was trying to use pedersen_commitment for that
-    // but that is currently not supported by the AVM (but might be soon).
     let function_source = format!(
         "
         fn compute_note_hiding_point(self: {}) -> aztec::protocol_types::point::Point {{
-            let h = aztec::hash::pedersen_hash(self.serialize_content(), aztec::protocol_types::constants::GENERATOR_INDEX__NOTE_HIDING_POINT);
-            aztec::generators::field_to_point(h)
+            aztec::hash::pedersen_commitment(self.serialize_content(), aztec::protocol_types::constants::GENERATOR_INDEX__NOTE_HIDING_POINT)
         }}
         ",
         note_type

yarn-project/simulator/src/client/simulator.test.ts

@@ -5,7 +5,7 @@ import { type FunctionArtifact, getFunctionArtifact } from '@aztec/foundation/ab
 import { AztecAddress } from '@aztec/foundation/aztec-address';
 import { poseidon2Hash } from '@aztec/foundation/crypto';
 import { Fr, type Point } from '@aztec/foundation/fields';
-import { TokenContractArtifact } from '@aztec/noir-contracts.js/Token';
+import { TokenBlacklistContractArtifact } from '@aztec/noir-contracts.js';
 
 import { type MockProxy, mock } from 'jest-mock-extended';
 
@@ -47,10 +47,13 @@ describe('Simulator', () => {
   });
 
   describe('computeNoteHashAndOptionallyANullifier', () => {
-    const artifact = getFunctionArtifact(TokenContractArtifact, 'compute_note_hash_and_optionally_a_nullifier');
+    const artifact = getFunctionArtifact(
+      TokenBlacklistContractArtifact,
+      'compute_note_hash_and_optionally_a_nullifier',
+    );
     const nonce = Fr.random();
-    const storageSlot = TokenContractArtifact.storageLayout['balances'].slot;
-    const noteTypeId = TokenContractArtifact.notes['TokenNote'].id;
+    const storageSlot = TokenBlacklistContractArtifact.storageLayout['balances'].slot;
+    const noteTypeId = TokenBlacklistContractArtifact.notes['TokenNote'].id;
 
     const createNote = (amount = 123n) => new Note([new Fr(amount), ownerMasterNullifierPublicKey.hash(), Fr.random()]);
 

yarn-project/simulator/src/client/test_utils.ts

@@ -1,6 +1,6 @@
 import { Fq, Fr, GeneratorIndex, Point } from '@aztec/circuits.js';
 import { Grumpkin } from '@aztec/circuits.js/barretenberg';
-import { pedersenHash } from '@aztec/foundation/crypto';
+import { pedersenCommit } from '@aztec/foundation/crypto';
 
 // Copied over from `noir-projects/aztec-nr/aztec/src/generators.nr`
 const G_SLOT = new Point(
@@ -15,10 +15,11 @@ const G_SLOT = new Point(
  * @returns A note hiding point.
  */
 export function computeNoteHidingPoint(noteContent: Fr[]): Point {
-  // TODO(#7551): how this is computed will need to be updated
-  const h = pedersenHash(noteContent, GeneratorIndex.NOTE_HIDING_POINT);
-  const grumpkin = new Grumpkin();
-  return grumpkin.mul(G_SLOT, new Fq(h.toBigInt()));
+  const c = pedersenCommit(
+    noteContent.map(f => f.toBuffer()),
+    GeneratorIndex.NOTE_HIDING_POINT,
+  );
+  return new Point(new Fr(c[0]), new Fr(c[1]), false);
 }
 
 /**