refactor(stm): removed srs downsizing from the tests

Author: damrobi

mithril-stm/src/circuits/halo2_ivc/tests/common/generators/setup.rs

@@ -173,17 +173,19 @@ pub(crate) fn build_deterministic_params(circuit_degree: u32) -> ParamsKZG<Bls12
     ParamsKZG::<Bls12>::unsafe_setup(circuit_degree, ChaCha20Rng::seed_from_u64(ASSET_SEED))
 }
 
-/// Derives circuit-specific commitment parameters from a shared universal SRS.
+/// Returns commitment parameters for `circuit_degree`. Reuses `universal_kzg_parameters`
+/// directly when it already matches, otherwise generates fresh parameters at `circuit_degree`
+/// with the same deterministic seed.
 pub(super) fn derive_commitment_params(
     universal_kzg_parameters: &ParamsKZG<Bls12>,
     shared_srs_degree: u32,
     circuit_degree: u32,
 ) -> ParamsKZG<Bls12> {
-    let mut commitment_parameters = universal_kzg_parameters.clone();
-    if circuit_degree < shared_srs_degree {
-        commitment_parameters.downsize(circuit_degree);
+    if circuit_degree == shared_srs_degree {
+        universal_kzg_parameters.clone()
+    } else {
+        build_deterministic_params(circuit_degree)
     }
-    commitment_parameters
 }
 
 /// Builds the shared verifier-side recursive setup from the deterministic SRS.

mithril-stm/src/circuits/halo2_ivc/tests/common/generators/verification_key.rs

@@ -21,8 +21,6 @@ use crate::{
 use super::setup::build_deterministic_params;
 
 pub(crate) fn golden_recursive_circuit_verification_key_bytes() -> Vec<u8> {
-    let srs_for_recursive_circuit = build_deterministic_params(RECURSIVE_CIRCUIT_DEGREE);
-
     let small_parameters = Parameters {
         m: 10,
         k: 1,
@@ -32,8 +30,8 @@ pub(crate) fn golden_recursive_circuit_verification_key_bytes() -> Vec<u8> {
     let circuit = StmCertificateCircuit::try_new(&small_parameters, merkle_tree_depth).unwrap();
     let circuit_degree = MidnightCircuit::from_relation(&circuit, None).k();
 
-    let mut srs_for_non_recursive_circuit = srs_for_recursive_circuit.clone();
-    srs_for_non_recursive_circuit.downsize(circuit_degree);
+    let srs_for_non_recursive_circuit = build_deterministic_params(circuit_degree);
+    let srs_for_recursive_circuit = build_deterministic_params(RECURSIVE_CIRCUIT_DEGREE);
 
     let circuit_verification_key = NonRecursiveCircuitVerifyingKey::new(
         midnight_zk_stdlib::setup_vk(&srs_for_non_recursive_circuit, &circuit),

mithril-stm/src/protocol/aggregate_signature/clerk.rs

@@ -361,16 +361,12 @@ mod tests {
         params: Parameters,
         depth: u32,
     ) -> (Arc<IvcSnarkProverSetup>, NonRecursiveCircuitVerifyingKey) {
-        let srs: Arc<ParamsKZG<Bls12>> = Arc::new(ParamsKZG::<Bls12>::unsafe_setup(
-            12,
-            ChaCha20Rng::from_seed([42u8; 32]),
-        ));
         let circuit = StmCertificateCircuit::try_new(&params, depth)
             .expect("certificate circuit should build");
         let circuit_degree = MidnightCircuit::from_relation(&circuit, None).k();
 
-        let mut cert_srs = (*srs).clone();
-        cert_srs.downsize(circuit_degree);
+        let cert_srs =
+            ParamsKZG::<Bls12>::unsafe_setup(circuit_degree, ChaCha20Rng::from_seed([42u8; 32]));
 
         let midnight_vk = zk::setup_vk(&cert_srs, &circuit);
         let midnight_pk = zk::setup_pk(&circuit, &midnight_vk);