From 3204df13f1f0db4c2a21beb9edc69fbafabdd60e Mon Sep 17 00:00:00 2001
From: Rostyslav Tyshko <tyshko.rostyslav@gmail.com>
Date: Mon, 2 Dec 2024 01:19:42 +0100
Subject: [PATCH] add se kernel impl and verify_commitment to de module

---
 node_core/src/executions/se.rs | 50 ++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/node_core/src/executions/se.rs b/node_core/src/executions/se.rs
index 0eaaab7..8428fbc 100644
--- a/node_core/src/executions/se.rs
+++ b/node_core/src/executions/se.rs
@@ -113,3 +113,53 @@ pub fn validate_nullifiers_proof(
 
     nsmt.get_non_membership_proof(nullifier).unwrap().1.is_none()
 }
+
+// Check balances
+
+//  takes the public_info and output_utxos[], 
+// returns the True if the token amount in public_info matches the sum of all output_utxos[], otherwise return False.
+pub fn check_balances(public_info: u128, output_utxos: &[UTXO]) -> bool {
+    let total_output: u128 = output_utxos.iter().map(|utxo| utxo.amount).sum();
+    public_info == total_output
+}
+
+// Verify Pedersen commitment
+
+// takes the public_info, secret_r and pedersen_commitment and 
+// checks that commitment(public_info,secret_r) is equal pedersen_commitment where the commitment is pedersen commitment.
+pub fn verify_commitment(public_info: u64, secret_r: &[u8], pedersen_commitment: &PedersenCommitment) -> bool {
+    let commitment_secrets = CommitmentSecrets {
+        value: public_info,
+        value_blinding_factor: Tweak::from_slice(secret_r).unwrap(),
+        generator_blinding_factor: Tweak::new(&mut thread_rng()),
+    };
+
+    let tag = tag_random();
+    let commitment = commit(&commitment_secrets, tag);
+
+    commitment == *pedersen_commitment
+}
+
+fn se_kernel(
+    root_commitment: &[u8],
+    root_nullifier: [u8; 32],
+    public_info: u64,
+    pedersen_commitment: PedersenCommitment,
+    secret_r: &[u8],
+    output_utxos: &[UTXO],
+    in_commitments_proof: &[Vec<u8>],
+    nullifiers_proof: &[[u8; 32]],
+    nullifier_secret_key: Scalar,
+) -> (Vec<u8>, Vec<Vec<u8>>, Vec<u8>) {
+    check_balances(public_info as u128, output_utxos);
+
+    let out_commitments = generate_commitments(output_utxos);
+
+    let nullifier = generate_nullifiers(&pedersen_commitment, &nullifier_secret_key.to_bytes());
+
+    validate_in_commitments_proof(&pedersen_commitment, root_commitment.to_vec(), in_commitments_proof);
+
+    verify_commitment(public_info, secret_r, &pedersen_commitment);
+
+    (vec![], out_commitments, nullifier)
+}