From df1ac7ad835894a42dd9d384c92c59d647a4e334 Mon Sep 17 00:00:00 2001
From: anupsv <anupsv@users.noreply.github.com>
Date: Tue, 11 Feb 2025 14:52:44 -0800
Subject: [PATCH] casting to u64 explicitly (#45)

* casting to u64 explicitly

* casting to u64 in helpers.

* length already is u64

* adding 32bit test workflow

* cleaning up rutst-toolchain

* adding 32bit test target

* using cross test

* adding helper function for conversion

* cargo fmt
---
 .github/workflows/rust.yml |  5 ++++-
 primitives/Cargo.toml      |  2 +-
 primitives/src/helpers.rs  | 15 ++++++++++++++-
 prover/Cargo.toml          |  2 +-
 rust-toolchain             |  2 +-
 verifier/Cargo.toml        |  4 ++--
 verifier/src/batch.rs      |  5 ++---
 7 files changed, 25 insertions(+), 10 deletions(-)

diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
index 5bb0da8..c9b9949 100644
--- a/.github/workflows/rust.yml
+++ b/.github/workflows/rust.yml
@@ -11,7 +11,6 @@ env:
 
 jobs:
   build:
-
     runs-on: ubuntu-latest
     timeout-minutes: 30
     steps:
@@ -24,5 +23,9 @@ jobs:
       run: cargo clippy --all --manifest-path Cargo.toml -- -D warnings
     - name: Run tests
       run: cargo test --verbose
+    - name: 32bit compilation test
+      run: cargo build --target i686-unknown-linux-gnu --verbose
+    - name: Running tests under 32bit architecture
+      run: cargo install cross && cross test --target i686-unknown-linux-gnu --verbose
 
     
diff --git a/primitives/Cargo.toml b/primitives/Cargo.toml
index 7e71bf0..d2747a8 100644
--- a/primitives/Cargo.toml
+++ b/primitives/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "rust-kzg-bn254-primitives"
-version = "0.1.0"
+version = "0.1.1"
 description = "This library offers a set of structs, traits and functions for generating Blobs and Polynomials which are used to interact with rust-kzg-bn254-prover and rust-kzg-bn254-verifier crates."
 edition.workspace = true
 repository.workspace = true
diff --git a/primitives/src/helpers.rs b/primitives/src/helpers.rs
index 9aa6279..60af0e7 100644
--- a/primitives/src/helpers.rs
+++ b/primitives/src/helpers.rs
@@ -518,7 +518,7 @@ pub fn compute_challenge(blob: &Blob, commitment: &G1Affine) -> Result<Fr, KzgEr
 
     // Step 2: Copy the number of field elements (blob polynomial length)
     // Convert to bytes using the configured endianness
-    let number_of_field_elements = blob_poly.len().to_be_bytes();
+    let number_of_field_elements = usize_to_be_bytes(blob_poly.len());
     digest_bytes[offset..offset + 8].copy_from_slice(&number_of_field_elements);
     offset += 8;
 
@@ -717,3 +717,16 @@ pub fn compute_challenges_and_evaluate_polynomial(
     // These will be used in the KZG proof verification process
     Ok((evaluation_challenges, ys))
 }
+
+/// Converts a usize to a byte array in big-endian format always returning 8 bytes.
+pub fn usize_to_be_bytes(number: usize) -> [u8; 8] {
+    let mut result = [0u8; 8];
+    let number_bytes = number.to_be_bytes();
+
+    if number_bytes.len() == 4 {
+        result[4..].copy_from_slice(&number_bytes);
+    } else {
+        result.copy_from_slice(&number_bytes);
+    }
+    result
+}
diff --git a/prover/Cargo.toml b/prover/Cargo.toml
index 5d950e0..1990b45 100644
--- a/prover/Cargo.toml
+++ b/prover/Cargo.toml
@@ -10,7 +10,7 @@ license-file.workspace = true
 exclude = ["tests/*", "benches/*"]
 
 [dependencies]
-rust-kzg-bn254-primitives = { version = "0.1.0" }
+rust-kzg-bn254-primitives = { version = "0.1.1", path = "../primitives" }
 ark-bn254 = "0.5.0"
 ark-ec = { version = "0.5.0", features = ["parallel"] }
 ark-ff = { version = "0.5.0", features = ["parallel"] }
diff --git a/rust-toolchain b/rust-toolchain
index 9b97c89..cbdb9fc 100644
--- a/rust-toolchain
+++ b/rust-toolchain
@@ -2,4 +2,4 @@
 channel = '1.81'
 profile = 'minimal'
 components = ['clippy', 'rustfmt']
-targets = ["x86_64-unknown-linux-gnu", "x86_64-pc-windows-gnu", "wasm32-unknown-unknown", "aarch64-apple-darwin"]
+targets = ["x86_64-unknown-linux-gnu", "aarch64-apple-darwin", "i686-unknown-linux-gnu"]
diff --git a/verifier/Cargo.toml b/verifier/Cargo.toml
index a84eaf7..dd7028c 100644
--- a/verifier/Cargo.toml
+++ b/verifier/Cargo.toml
@@ -8,7 +8,7 @@ rust-version.workspace = true
 repository.workspace = true
 
 [dependencies]
-rust-kzg-bn254-primitives = { version = "0.1.0" }
+rust-kzg-bn254-primitives = {version = "0.1.1", path = "../primitives" }
 ark-bn254 = "0.5.0"
 ark-ec = { version = "0.5.0", features = ["parallel"] }
 ark-ff = { version = "0.5.0", features = ["parallel"] }
@@ -19,7 +19,7 @@ rand = "0.8.5"
 criterion = "0.5"
 lazy_static = "1.5"
 ark-std = { version = "0.5.0", features = ["parallel"] }
-rust-kzg-bn254-prover = { version = "0.1.0" }
+rust-kzg-bn254-prover = { version = "0.1.0", path = "../prover" }
 
 [[bench]]
 name = "bench_kzg_verify"
diff --git a/verifier/src/batch.rs b/verifier/src/batch.rs
index ab9b93f..412b4f4 100644
--- a/verifier/src/batch.rs
+++ b/verifier/src/batch.rs
@@ -6,7 +6,7 @@ use rust_kzg_bn254_primitives::{
     blob::Blob,
     consts::{BYTES_PER_FIELD_ELEMENT, G2_TAU, RANDOM_CHALLENGE_KZG_BATCH_DOMAIN},
     errors::KzgError,
-    helpers::{self, is_on_curve_g1},
+    helpers::{self, is_on_curve_g1, usize_to_be_bytes},
 };
 
 /// Ref: https://github.com/ethereum/consensus-specs/blob/master/specs/deneb/polynomial-commitments.md#verify_blob_kzg_proof_batch
@@ -114,8 +114,7 @@ fn compute_r_powers(
     data_to_be_hashed[0..24].copy_from_slice(RANDOM_CHALLENGE_KZG_BATCH_DOMAIN);
 
     // Convert number of commitments to bytes and copy to buffer
-    // Uses configured endianness (Big or Little)
-    let n_bytes: [u8; 8] = n.to_be_bytes();
+    let n_bytes: [u8; 8] = usize_to_be_bytes(n);
     data_to_be_hashed[32..40].copy_from_slice(&n_bytes);
 
     let target_slice = &mut data_to_be_hashed[24..24 + (n * 8)];