Fix lib and types exposures

nomos-da/kzgrs-backend/Cargo.toml

@@ -6,6 +6,8 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+blake2 = "0.10"
+ark-serialize = "0.4.2"
 ark-poly = "0.4.2"
 kzgrs = { path = "../kzgrs" }
 rand = "0.8.5"

nomos-da/kzgrs-backend/src/common.rs

@@ -1,3 +1,8 @@
+use ark_serialize::CanonicalSerialize;
+use blake2::digest::{Update, VariableOutput};
+use kzgrs::Commitment;
+use std::io::Cursor;
+
 #[derive(Clone)]
 pub struct Chunk(Vec<u8>);
 pub struct Row(Vec<Chunk>);
@@ -68,3 +73,23 @@ impl FromIterator<Row> for ChunksMatrix {
         Self(iter.into_iter().collect())
     }
 }
+
+pub fn hash_column_and_commitment<const HASH_SIZE: usize>(
+    column: &Column,
+    commitment: &Commitment,
+) -> [u8; HASH_SIZE] {
+    use ark_serialize::CanonicalSerialize;
+    let mut hasher = blake2::Blake2bVar::new(HASH_SIZE)
+        .unwrap_or_else(|e| panic!("Blake2b should work for size {HASH_SIZE}, {e}"));
+    hasher.update(column.as_bytes().as_ref());
+    let mut buff = Cursor::new(vec![]);
+    commitment
+        .serialize_uncompressed(&mut buff)
+        .expect("Serialization of commitment should work");
+    hasher.update(buff.into_inner().as_ref());
+    hasher
+        .finalize_boxed()
+        .to_vec()
+        .try_into()
+        .unwrap_or_else(|_| panic!("Size is guaranteed by constant {HASH_SIZE:?}"))
+}

nomos-da/kzgrs/src/common.rs

@@ -1,5 +1,6 @@
 // std
 // crates
+use crate::Commitment;
 use ark_bls12_381::fr::Fr;
 use ark_ff::{BigInteger256, PrimeField, Zero};
 use ark_poly::domain::general::GeneralEvaluationDomain;

nomos-da/kzgrs/src/kzg.rs

@@ -28,7 +28,7 @@ pub fn generate_element_proof(
     element_index: usize,
     polynomial: &DensePolynomial<Fr>,
     global_parameters: &UniversalParams<Bls12_381>,
-    domain: &GeneralEvaluationDomain<Fr>,
+    domain: GeneralEvaluationDomain<Fr>,
 ) -> Result<Proof<Bls12_381>, KzgRsError> {
     let u = domain.element(element_index);
     let v = polynomial.evaluate(&u);

nomos-da/kzgrs/src/lib.rs

@@ -1,5 +1,5 @@
 pub mod common;
-mod global_parameters;
+pub mod global_parameters;
 pub mod kzg;
 pub mod rs;