From a47d40c8497a8fd6375bd940d46354992cb4159e Mon Sep 17 00:00:00 2001
From: iquerejeta <querejeta.azurmendi@iohk.io>
Date: Fri, 27 Dec 2024 15:44:43 +0100
Subject: [PATCH] Minor changes to run midnight_circuits

---
 Cargo.toml                     |  1 +
 src/poly/kzg/params.rs         |  7 +++++
 src/transcript/implementors.rs | 48 +++++++++++++++++++++++++++++++++-
 3 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/Cargo.toml b/Cargo.toml
index 393a017f1..fccd6f7b7 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -43,6 +43,7 @@ backtrace = { version = "0.3", optional = true }
 ff = "0.13"
 group = "0.13"
 halo2curves = { version = "0.7.0", default-features = false }
+blstrs = { git = "https://github.com/davidnevadoc/blstrs", rev = "8ca6da7" }
 rand_core = { version = "0.6", default-features = false }
 tracing = "0.1"
 blake2b_simd = "1" # MSRV 1.66.0
diff --git a/src/poly/kzg/params.rs b/src/poly/kzg/params.rs
index 454c10aca..f4aafd0b3 100644
--- a/src/poly/kzg/params.rs
+++ b/src/poly/kzg/params.rs
@@ -30,6 +30,13 @@ impl<E: Engine> Params for ParamsKZG<E> {
 }
 
 impl<E: Engine + Debug> ParamsKZG<E> {
+    /// Downsize the current parameters to match a smaller `k`.
+    pub fn downsize(&mut self, new_k: u32) {
+        assert!(new_k < self.g_lagrange.len() as u32);
+        self.g.truncate(new_k as usize);
+        self.g_lagrange = g_to_lagrange(self.g.iter().map(|g| g.to_curve()).collect(), new_k);
+    }
+
     /// Initializes parameters for the curve, draws toxic secret from given rng.
     /// MUST NOT be used in production.
     pub fn unsafe_setup<R: RngCore>(k: u32, rng: R) -> Self {
diff --git a/src/transcript/implementors.rs b/src/transcript/implementors.rs
index 7b171bb83..37d9cbcae 100644
--- a/src/transcript/implementors.rs
+++ b/src/transcript/implementors.rs
@@ -2,7 +2,7 @@ use crate::transcript::{
     Hashable, Sampleable, TranscriptHash, BLAKE2B_PREFIX_CHALLENGE, BLAKE2B_PREFIX_COMMON,
 };
 use blake2b_simd::{Params, State as Blake2bState};
-use ff::FromUniformBytes;
+use ff::{FromUniformBytes, PrimeField};
 use group::GroupEncoding;
 use halo2curves::bn256::{Fr, G1Affine};
 
@@ -52,3 +52,49 @@ impl Sampleable<Blake2bState> for Fr {
         Fr::from_uniform_bytes(&bytes)
     }
 }
+
+//////////////////////////////////////////////////////////
+/// Implementation of Hashable for BLS12-381 with Blake //
+//////////////////////////////////////////////////////////
+
+impl Hashable<Blake2bState> for blstrs::G1Affine {
+    fn to_input(&self) -> Vec<u8> {
+        self.to_bytes().as_ref().to_vec()
+    }
+}
+
+impl Hashable<Blake2bState> for blstrs::Scalar {
+    fn to_input(&self) -> Vec<u8> {
+        self.to_repr().to_vec()
+    }
+}
+
+impl Sampleable<Blake2bState> for blstrs::Scalar {
+    fn sample(out: Vec<u8>) -> Self {
+        assert!(out.len() <= 64);
+        let mut bytes = [0u8; 64];
+        bytes[..out.len()].copy_from_slice(&out);
+        blstrs::Scalar::from_uniform_bytes(&bytes)
+    }
+}
+
+impl Hashable<Blake2bState> for halo2curves::bls12381::G1Affine {
+    fn to_input(&self) -> Vec<u8> {
+        self.to_bytes().as_ref().to_vec()
+    }
+}
+
+impl Hashable<Blake2bState> for halo2curves::bls12381::Fr {
+    fn to_input(&self) -> Vec<u8> {
+        self.to_repr().as_ref().to_vec()
+    }
+}
+
+impl Sampleable<Blake2bState> for halo2curves::bls12381::Fr {
+    fn sample(out: Vec<u8>) -> Self {
+        assert!(out.len() <= 64);
+        let mut bytes = [0u8; 64];
+        bytes[..out.len()].copy_from_slice(&out);
+        halo2curves::bls12381::Fr::from_uniform_bytes(&bytes)
+    }
+}