From 2a513f509b97e616983525b3d3b607f080176636 Mon Sep 17 00:00:00 2001
From: Jay White <JayWhite2357@users.noreply.github.com>
Date: Thu, 23 Jan 2025 18:31:42 -0500
Subject: [PATCH] feat!: improve hyperkzg api (#353)

* feat!: make field elements serialize into transcript in big-endian form

This makes the transcript more compatible with the EVM, which is big-endian

* feat: expose hyperkzg underlying group

This is accomplished via `new` and `into_inner` methods

* feat: expose hyperkzg argument underlying elements

This is accomplished via `com`, `w`, and `v` accessors.

* feat: add `setup_from_rng` for hyperkzg::CommitmentKey

This can be used instead of `CommitmentEngineTrait::setup` to generate a reproducible commitment key
---
 src/provider/hyperkzg.rs | 63 +++++++++++++++++++++++++++++++++-------
 src/provider/keccak.rs   | 12 ++++----
 src/provider/traits.rs   |  7 +++--
 3 files changed, 63 insertions(+), 19 deletions(-)

diff --git a/src/provider/hyperkzg.rs b/src/provider/hyperkzg.rs
index 4ee1f956..99bb7a3e 100644
--- a/src/provider/hyperkzg.rs
+++ b/src/provider/hyperkzg.rs
@@ -71,6 +71,20 @@ where
   comm: <E as Engine>::GE,
 }
 
+impl<E: Engine> Commitment<E>
+where
+  E::GE: PairingGroup,
+{
+  /// Creates a new commitment from the underlying group element
+  pub fn new(comm: <E as Engine>::GE) -> Self {
+    Commitment { comm }
+  }
+  /// Returns the commitment as a group element
+  pub fn into_inner(self) -> <E as Engine>::GE {
+    self.comm
+  }
+}
+
 impl<E: Engine> CommitmentTrait<E> for Commitment<E>
 where
   E::GE: PairingGroup,
@@ -178,18 +192,14 @@ pub struct CommitmentEngine<E: Engine> {
   _p: PhantomData<E>,
 }
 
-impl<E: Engine> CommitmentEngineTrait<E> for CommitmentEngine<E>
+impl<E: Engine> CommitmentKey<E>
 where
   E::GE: PairingGroup,
 {
-  type Commitment = Commitment<E>;
-  type CommitmentKey = CommitmentKey<E>;
-  type DerandKey = DerandKey<E>;
-
-  fn setup(label: &'static [u8], n: usize) -> Self::CommitmentKey {
-    // NOTE: this is for testing purposes and should not be used in production
-    // TODO: we need to decide how to generate load/store parameters
-    let tau = E::Scalar::random(OsRng);
+  /// NOTE: this is for testing purposes and should not be used in production
+  /// This can be used instead of `setup` to generate a reproducible commitment key
+  pub fn setup_from_rng(label: &'static [u8], n: usize, rng: impl rand_core::RngCore) -> Self {
+    let tau = E::Scalar::random(rng);
     let num_gens = n.next_power_of_two();
 
     // Compute powers of tau in E::Scalar, then scalar muls in parallel
@@ -208,7 +218,22 @@ where
 
     let tau_H = (<<E::GE as PairingGroup>::G2 as DlogGroup>::gen() * tau).affine();
 
-    Self::CommitmentKey { ck, h, tau_H }
+    Self { ck, h, tau_H }
+  }
+}
+
+impl<E: Engine> CommitmentEngineTrait<E> for CommitmentEngine<E>
+where
+  E::GE: PairingGroup,
+{
+  type Commitment = Commitment<E>;
+  type CommitmentKey = CommitmentKey<E>;
+  type DerandKey = DerandKey<E>;
+
+  fn setup(label: &'static [u8], n: usize) -> Self::CommitmentKey {
+    // NOTE: this is for testing purposes and should not be used in production
+    // TODO: we need to decide how to generate load/store parameters
+    Self::CommitmentKey::setup_from_rng(label, n, OsRng)
   }
 
   fn derand_key(ck: &Self::CommitmentKey) -> Self::DerandKey {
@@ -270,6 +295,24 @@ where
   v: Vec<Vec<E::Scalar>>,
 }
 
+impl<E: Engine> EvaluationArgument<E>
+where
+  E::GE: PairingGroup,
+{
+  /// The KZG commitments to intermediate polynomials
+  pub fn com(&self) -> &[G1Affine<E>] {
+    &self.com
+  }
+  /// The KZG witnesses for batch openings
+  pub fn w(&self) -> &[G1Affine<E>] {
+    &self.w
+  }
+  /// The evaluations of the polynomials at challenge points
+  pub fn v(&self) -> &[Vec<E::Scalar>] {
+    &self.v
+  }
+}
+
 /// Provides an implementation of a polynomial evaluation engine using KZG
 #[derive(Clone, Debug, Serialize, Deserialize)]
 pub struct EvaluationEngine<E: Engine> {
diff --git a/src/provider/keccak.rs b/src/provider/keccak.rs
index 82bf37d6..48cf50fb 100644
--- a/src/provider/keccak.rs
+++ b/src/provider/keccak.rs
@@ -137,18 +137,18 @@ mod tests {
   #[test]
   fn test_keccak_transcript() {
     test_keccak_transcript_with::<PallasEngine>(
-      "5ddffa8dc091862132788b8976af88b9a2c70594727e611c7217ba4c30c8c70a",
-      "4d4bf42c065870395749fa1c4fb641df1e0d53f05309b03d5b1db7f0be3aa13d",
+      "b67339da79ce5f6dc72ad23c8c3b4179f49655cadf92d47e79c3e7788f00f125",
+      "b7f033d47b3519dd6efe320b995eaad1dc11712cb9b655d2e7006ed5f86bd321",
     );
 
     test_keccak_transcript_with::<Bn256EngineKZG>(
-      "9fb71e3b74bfd0b60d97349849b895595779a240b92a6fae86bd2812692b6b0e",
-      "bfd4c50b7d6317e9267d5d65c985eb455a3561129c0b3beef79bfc8461a84f18",
+      "b387ba3a8b9a22b3b7544a3dbbd26a048a1d354d8dc582c64d1513335e66a205",
+      "73ad65097d947fe45de5241bb340bbd97b198b52cc559a9657f73c361bf8700b",
     );
 
     test_keccak_transcript_with::<Secp256k1Engine>(
-      "9723aafb69ec8f0e9c7de756df0993247d98cf2b2f72fa353e3de654a177e310",
-      "a6a90fcb6e1b1a2a2f84c950ef1510d369aea8e42085f5c629bfa66d00255f25",
+      "f15ddd8fa1675a9e273e0ef441711005d77a5fd485f4e6cdee59760ca01493fa",
+      "3c019f0e557abaecc99790382974cb27132bfe038af9c4d43a33ec9c426e19f5",
     );
   }
 
diff --git a/src/provider/traits.rs b/src/provider/traits.rs
index a790fd45..36f41546 100644
--- a/src/provider/traits.rs
+++ b/src/provider/traits.rs
@@ -197,15 +197,16 @@ macro_rules! impl_traits {
 
     impl<G: Group> TranscriptReprTrait<G> for $name::Scalar {
       fn to_transcript_bytes(&self) -> Vec<u8> {
-        self.to_bytes().to_vec()
+        self.to_bytes().into_iter().rev().collect()
       }
     }
 
     impl<G: DlogGroup> TranscriptReprTrait<G> for $name::Affine {
       fn to_transcript_bytes(&self) -> Vec<u8> {
         let coords = self.coordinates().unwrap();
-
-        [coords.x().to_bytes(), coords.y().to_bytes()].concat()
+        let x_bytes = coords.x().to_bytes().into_iter();
+        let y_bytes = coords.y().to_bytes().into_iter();
+        x_bytes.rev().chain(y_bytes.rev()).collect()
       }
     }
   };