From bbfc00edf75be23ba985662a6303e9713b14faf6 Mon Sep 17 00:00:00 2001
From: Kevaundray Wedderburn <kevtheappdev@gmail.com>
Date: Mon, 23 Sep 2024 21:22:53 +0100
Subject: [PATCH] DefaultCommitter now uses Windowed version for first five
 elements

---
 banderwagon/src/msm_windowed_sign.rs |  1 +
 ipa-multipoint/src/committer.rs      | 19 ++++++++++++++++---
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/banderwagon/src/msm_windowed_sign.rs b/banderwagon/src/msm_windowed_sign.rs
index be7c84e..b55de0a 100644
--- a/banderwagon/src/msm_windowed_sign.rs
+++ b/banderwagon/src/msm_windowed_sign.rs
@@ -5,6 +5,7 @@ use ark_ff::Zero;
 use ark_ff::{BigInteger, BigInteger256};
 use std::ops::Neg;
 
+#[derive(Debug, Clone)]
 pub struct MSMPrecompWindowSigned {
     tables: Vec<Vec<EdwardsAffine>>,
     num_windows: usize,
diff --git a/ipa-multipoint/src/committer.rs b/ipa-multipoint/src/committer.rs
index 968877e..e97a470 100644
--- a/ipa-multipoint/src/committer.rs
+++ b/ipa-multipoint/src/committer.rs
@@ -1,4 +1,4 @@
-use banderwagon::{msm::MSMPrecompWnaf, Element, Fr};
+use banderwagon::{msm::MSMPrecompWnaf, msm_windowed_sign::MSMPrecompWindowSigned, Element, Fr};
 
 // This is the functionality that commits to the branch nodes and computes the delta optimization
 // For consistency with the Pcs, ensure that this component uses the same CRS as the Pcs
@@ -24,19 +24,32 @@ pub trait Committer {
 
 #[derive(Clone, Debug)]
 pub struct DefaultCommitter {
+    precomp_first_five: MSMPrecompWindowSigned,
     precomp: MSMPrecompWnaf,
 }
 
 impl DefaultCommitter {
     pub fn new(points: &[Element]) -> Self {
-        let precomp = MSMPrecompWnaf::new(points, 12);
+        // Take the first five elements and use a more aggressive optimization strategy
+        // since they are used for computing storage keys.
 
-        Self { precomp }
+        let (points_five, rest) = points.split_at(5);
+
+        let precomp_first_five = MSMPrecompWindowSigned::new(points_five, 16);
+        let precomp = MSMPrecompWnaf::new(rest, 12);
+
+        Self {
+            precomp,
+            precomp_first_five,
+        }
     }
 }
 
 impl Committer for DefaultCommitter {
     fn commit_lagrange(&self, evaluations: &[Fr]) -> Element {
+        if evaluations.len() <= 5 {
+            return self.precomp_first_five.mul(&evaluations);
+        }
         // Preliminary benchmarks indicate that the parallel version is faster
         // for vectors of length 64 or more
         if evaluations.len() >= 64 {