From 596d91f722d4c0773fceb6623f16ad7a2667a3e6 Mon Sep 17 00:00:00 2001
From: Pratyush Mishra <pratyushmishra@berkeley.edu>
Date: Wed, 17 Jan 2024 11:24:03 -0500
Subject: [PATCH] Update FixedBaseMSM to match algebra (#55)

---
 src/generator.rs | 44 ++++++++++++++------------------------------
 1 file changed, 14 insertions(+), 30 deletions(-)

diff --git a/src/generator.rs b/src/generator.rs
index 91f7936..15aee16 100644
--- a/src/generator.rs
+++ b/src/generator.rs
@@ -1,6 +1,6 @@
 use crate::{r1cs_to_qap::R1CSToQAP, Groth16, ProvingKey, Vec, VerifyingKey};
-use ark_ec::{pairing::Pairing, scalar_mul::fixed_base::FixedBase, CurveGroup};
-use ark_ff::{Field, PrimeField, UniformRand, Zero};
+use ark_ec::{pairing::Pairing, scalar_mul::BatchMulPreprocessing, CurveGroup};
+use ark_ff::{Field, UniformRand, Zero};
 use ark_poly::{EvaluationDomain, GeneralEvaluationDomain};
 use ark_relations::r1cs::{
     ConstraintSynthesizer, ConstraintSystem, OptimizationGoal, Result as R1CSResult,
@@ -107,8 +107,6 @@ impl<E: Pairing, QAP: R1CSToQAP> Groth16<E, QAP> {
             .map(|i| usize::from(!b[i].is_zero()))
             .sum();
 
-        let scalar_bits = E::ScalarField::MODULUS_BIT_SIZE as usize;
-
         let gamma_inverse = gamma.inverse().ok_or(SynthesisError::UnexpectedIdentity)?;
         let delta_inverse = delta.inverse().ok_or(SynthesisError::UnexpectedIdentity)?;
 
@@ -128,21 +126,19 @@ impl<E: Pairing, QAP: R1CSToQAP> Groth16<E, QAP> {
 
         // Compute B window table
         let g2_time = start_timer!(|| "Compute G2 table");
-        let g2_window = FixedBase::get_mul_window_size(non_zero_b);
-        let g2_table = FixedBase::get_window_table::<E::G2>(scalar_bits, g2_window, g2_generator);
+        let g2_table = BatchMulPreprocessing::new(g2_generator, non_zero_b);
         end_timer!(g2_time);
 
         // Compute the B-query in G2
         let b_g2_time = start_timer!(|| format!("Calculate B G2 of size {}", b.len()));
-        let b_g2_query = FixedBase::msm::<E::G2>(scalar_bits, g2_window, &g2_table, &b);
+        let b_g2_query = g2_table.batch_mul(&b);
         drop(g2_table);
         end_timer!(b_g2_time);
 
         // Compute G window table
         let g1_window_time = start_timer!(|| "Compute G1 window table");
-        let g1_window =
-            FixedBase::get_mul_window_size(non_zero_a + non_zero_b + qap_num_variables + m_raw + 1);
-        let g1_table = FixedBase::get_window_table::<E::G1>(scalar_bits, g1_window, g1_generator);
+        let num_scalars = non_zero_a + non_zero_b + qap_num_variables + m_raw + 1;
+        let g1_table = BatchMulPreprocessing::new(g1_generator, num_scalars);
         end_timer!(g1_window_time);
 
         // Generate the R1CS proving key
@@ -156,30 +152,26 @@ impl<E: Pairing, QAP: R1CSToQAP> Groth16<E, QAP> {
 
         // Compute the A-query
         let a_time = start_timer!(|| "Calculate A");
-        let a_query = FixedBase::msm::<E::G1>(scalar_bits, g1_window, &g1_table, &a);
+        let a_query = g1_table.batch_mul(&a);
         drop(a);
         end_timer!(a_time);
 
         // Compute the B-query in G1
         let b_g1_time = start_timer!(|| "Calculate B G1");
-        let b_g1_query = FixedBase::msm::<E::G1>(scalar_bits, g1_window, &g1_table, &b);
+        let b_g1_query = g1_table.batch_mul(&b);
         drop(b);
         end_timer!(b_g1_time);
 
         // Compute the H-query
         let h_time = start_timer!(|| "Calculate H");
-        let h_query = FixedBase::msm::<E::G1>(
-            scalar_bits,
-            g1_window,
-            &g1_table,
-            &QAP::h_query_scalars::<_, D<E::ScalarField>>(m_raw - 1, t, zt, delta_inverse)?,
-        );
-
+        let h_scalars =
+            QAP::h_query_scalars::<_, D<E::ScalarField>>(m_raw - 1, t, zt, delta_inverse)?;
+        let h_query = g1_table.batch_mul(&h_scalars);
         end_timer!(h_time);
 
         // Compute the L-query
         let l_time = start_timer!(|| "Calculate L");
-        let l_query = FixedBase::msm::<E::G1>(scalar_bits, g1_window, &g1_table, &l);
+        let l_query = g1_table.batch_mul(&l);
         drop(l);
         end_timer!(l_time);
 
@@ -188,8 +180,7 @@ impl<E: Pairing, QAP: R1CSToQAP> Groth16<E, QAP> {
         // Generate R1CS verification key
         let verifying_key_time = start_timer!(|| "Generate the R1CS verification key");
         let gamma_g2 = g2_generator * &gamma;
-        let gamma_abc_g1 = FixedBase::msm::<E::G1>(scalar_bits, g1_window, &g1_table, &gamma_abc);
-
+        let gamma_abc_g1 = g1_table.batch_mul(&gamma_abc);
         drop(g1_table);
 
         end_timer!(verifying_key_time);
@@ -199,16 +190,9 @@ impl<E: Pairing, QAP: R1CSToQAP> Groth16<E, QAP> {
             beta_g2: beta_g2.into_affine(),
             gamma_g2: gamma_g2.into_affine(),
             delta_g2: delta_g2.into_affine(),
-            gamma_abc_g1: E::G1::normalize_batch(&gamma_abc_g1),
+            gamma_abc_g1,
         };
 
-        let batch_normalization_time = start_timer!(|| "Convert proving key elements to affine");
-        let a_query = E::G1::normalize_batch(&a_query);
-        let b_g1_query = E::G1::normalize_batch(&b_g1_query);
-        let b_g2_query = E::G2::normalize_batch(&b_g2_query);
-        let h_query = E::G1::normalize_batch(&h_query);
-        let l_query = E::G1::normalize_batch(&l_query);
-        end_timer!(batch_normalization_time);
         end_timer!(setup_time);
 
         Ok(ProvingKey {