Improve clarity on n vs. k

packages/crypto/benches/main.rs

@@ -157,12 +157,14 @@ where
             .map(|(secret_key, message)| *message * secret_key)
             .collect();
 
-        for i in 1..=two_pow_max {
-            let num_points = 2_usize.pow(i);
-            let messages = &messages[..num_points];
-            let keys = &public_keys[..num_points];
+        for i in 0..=two_pow_max {
+            let n = 2_usize.pow(i); // the number of pairings on the left hand side
+            let k = n + 1; // the number of pairings in total
+            let messages: &[ark_ec::short_weierstrass::Affine<ark_bls12_381::g2::Config>] =
+                &messages[..n];
+            let keys = &public_keys[..n];
             let aggregated_signature: G2Affine =
-                signatures[..num_points].iter().sum::<G2Projective>().into();
+                signatures[..n].iter().sum::<G2Projective>().into();
 
             let serialized_pubkeys: Vec<u8> = keys
                 .iter()
@@ -187,7 +189,7 @@ where
                 .serialize_compressed(&mut serialized_signature[..])
                 .unwrap();
 
-            group.bench_function(format!("bls12_381_pairing_equality_{num_points}"), |b| {
+            group.bench_function(format!("bls12_381_pairing_equality_k={k}"), |b| {
                 b.iter(|| {
                     let is_valid = black_box(bls12_381_pairing_equality(
                         &serialized_pubkeys,

packages/vm/src/imports.rs

@@ -372,14 +372,19 @@ pub fn do_bls12_381_pairing_equality<
     let r = read_region(&memory, r_ptr, BLS12_381_G1_POINT_LEN)?;
     let s = read_region(&memory, s_ptr, BLS12_381_G2_POINT_LEN)?;
 
-    let estimated_point_count = (ps.len() / BLS12_381_G1_POINT_LEN) as u64;
+    // The values here are only correct if ps and qs can be divided by the point size.
+    // They are good enough for gas since we error in `bls12_381_pairing_equality` if the inputs are
+    // not properly formatted.
+    let estimated_n = (ps.len() / BLS12_381_G1_POINT_LEN) as u64;
+    // The number of parings to compute (`n` on the left hand side and `k = n + 1` in total)
+    let estimated_k = estimated_n + 1;
 
     let gas_info = GasInfo::with_cost(
         // Add one to the `estimated_point_count` since we do not include any pairs in the base
         // benchmark, and we always need to add one for the `r` and `s` pair.
         data.gas_config
             .bls12_381_pairing_equality_cost
-            .total_cost(estimated_point_count + 1),
+            .total_cost(estimated_k),
     );
     process_gas_info(data, &mut store, gas_info)?;