From 558a2bfa460eb5d40cd0b0ef8bde6de997094fc5 Mon Sep 17 00:00:00 2001
From: Luke Parker <lukeparker5132@gmail.com>
Date: Sun, 21 Apr 2024 21:51:44 -0400
Subject: [PATCH] Slight tweaks to BP+

---
 coins/monero/src/ringct/bulletproofs/mod.rs   |  2 +-
 .../plus/aggregate_range_proof.rs             | 37 ++++++++-----------
 .../plus/weighted_inner_product.rs            |  2 +-
 .../plus/aggregate_range_proof.rs             |  2 +-
 4 files changed, 19 insertions(+), 24 deletions(-)

diff --git a/coins/monero/src/ringct/bulletproofs/mod.rs b/coins/monero/src/ringct/bulletproofs/mod.rs
index df0c6ff8..ce9f7492 100644
--- a/coins/monero/src/ringct/bulletproofs/mod.rs
+++ b/coins/monero/src/ringct/bulletproofs/mod.rs
@@ -91,7 +91,7 @@ impl Bulletproofs {
       Bulletproofs::Plus(
         AggregateRangeStatement::new(outputs.iter().map(|com| DfgPoint(com.calculate())).collect())
           .unwrap()
-          .prove(rng, &Zeroizing::new(AggregateRangeWitness::new(outputs).unwrap()))
+          .prove(rng, &Zeroizing::new(AggregateRangeWitness::new(outputs.to_vec()).unwrap()))
           .unwrap(),
       )
     })
diff --git a/coins/monero/src/ringct/bulletproofs/plus/aggregate_range_proof.rs b/coins/monero/src/ringct/bulletproofs/plus/aggregate_range_proof.rs
index af5c0275..cba95014 100644
--- a/coins/monero/src/ringct/bulletproofs/plus/aggregate_range_proof.rs
+++ b/coins/monero/src/ringct/bulletproofs/plus/aggregate_range_proof.rs
@@ -24,7 +24,7 @@ use crate::{
   },
 };
 
-// Figure 3
+// Figure 3 of the Bulletproofs+ Paper
 #[derive(Clone, Debug)]
 pub(crate) struct AggregateRangeStatement {
   generators: Generators,
@@ -38,24 +38,15 @@ impl Zeroize for AggregateRangeStatement {
 }
 
 #[derive(Clone, Debug, Zeroize, ZeroizeOnDrop)]
-pub(crate) struct AggregateRangeWitness {
-  values: Vec<u64>,
-  gammas: Vec<Scalar>,
-}
+pub(crate) struct AggregateRangeWitness(Vec<Commitment>);
 
 impl AggregateRangeWitness {
-  pub(crate) fn new(commitments: &[Commitment]) -> Option<Self> {
+  pub(crate) fn new(commitments: Vec<Commitment>) -> Option<Self> {
     if commitments.is_empty() || (commitments.len() > MAX_M) {
       return None;
     }
 
-    let mut values = Vec::with_capacity(commitments.len());
-    let mut gammas = Vec::with_capacity(commitments.len());
-    for commitment in commitments {
-      values.push(commitment.amount);
-      gammas.push(Scalar(commitment.mask));
-    }
-    Some(AggregateRangeWitness { values, gammas })
+    Some(AggregateRangeWitness(commitments))
   }
 }
 
@@ -162,13 +153,11 @@ impl AggregateRangeStatement {
     witness: &AggregateRangeWitness,
   ) -> Option<AggregateRangeProof> {
     // Check for consistency with the witness
-    if self.V.len() != witness.values.len() {
+    if self.V.len() != witness.0.len() {
       return None;
     }
-    for (commitment, (value, gamma)) in
-      self.V.iter().zip(witness.values.iter().zip(witness.gammas.iter()))
-    {
-      if Commitment::new(**gamma, *value).calculate() != **commitment {
+    for (commitment, witness) in self.V.iter().zip(witness.0.iter()) {
+      if witness.calculate() != **commitment {
         return None;
       }
     }
@@ -196,7 +185,13 @@ impl AggregateRangeStatement {
     let mut a_l = ScalarVector(Vec::with_capacity(V.len() * N));
     for j in 1 ..= V.len() {
       d_js.push(Self::d_j(j, V.len()));
-      a_l.0.append(&mut u64_decompose(*witness.values.get(j - 1).unwrap_or(&0)).0);
+      #[allow(clippy::map_unwrap_or)]
+      a_l.0.append(
+        &mut u64_decompose(
+          *witness.0.get(j - 1).map(|commitment| &commitment.amount).unwrap_or(&0),
+        )
+        .0,
+      );
     }
 
     let a_r = a_l.clone() - Scalar::ONE;
@@ -223,8 +218,8 @@ impl AggregateRangeStatement {
     let a_l = a_l - z;
     let a_r = a_r + &d_descending_y_plus_z;
     let mut alpha = alpha;
-    for j in 1 ..= witness.gammas.len() {
-      alpha += z_pow[j - 1] * witness.gammas[j - 1] * y_mn_plus_one;
+    for j in 1 ..= witness.0.len() {
+      alpha += z_pow[j - 1] * Scalar(witness.0[j - 1].mask) * y_mn_plus_one;
     }
 
     Some(AggregateRangeProof {
diff --git a/coins/monero/src/ringct/bulletproofs/plus/weighted_inner_product.rs b/coins/monero/src/ringct/bulletproofs/plus/weighted_inner_product.rs
index 09bb6748..7cb9a4df 100644
--- a/coins/monero/src/ringct/bulletproofs/plus/weighted_inner_product.rs
+++ b/coins/monero/src/ringct/bulletproofs/plus/weighted_inner_product.rs
@@ -15,7 +15,7 @@ use crate::ringct::bulletproofs::plus::{
   ScalarVector, PointVector, GeneratorsList, Generators, padded_pow_of_2, transcript::*,
 };
 
-// Figure 1
+// Figure 1 of the Bulletproofs+ paper
 #[derive(Clone, Debug)]
 pub(crate) struct WipStatement {
   generators: Generators,
diff --git a/coins/monero/src/tests/bulletproofs/plus/aggregate_range_proof.rs b/coins/monero/src/tests/bulletproofs/plus/aggregate_range_proof.rs
index a50b9d40..658da250 100644
--- a/coins/monero/src/tests/bulletproofs/plus/aggregate_range_proof.rs
+++ b/coins/monero/src/tests/bulletproofs/plus/aggregate_range_proof.rs
@@ -21,7 +21,7 @@ fn test_aggregate_range_proof() {
     }
     let commitment_points = commitments.iter().map(|com| EdwardsPoint(com.calculate())).collect();
     let statement = AggregateRangeStatement::new(commitment_points).unwrap();
-    let witness = AggregateRangeWitness::new(&commitments).unwrap();
+    let witness = AggregateRangeWitness::new(commitments).unwrap();
 
     let proof = statement.clone().prove(&mut OsRng, &witness).unwrap();
     statement.verify(&mut OsRng, &mut verifier, (), proof);