From 905c5eb5a0de6091219e6abd4eb8bbc0f90f95b1 Mon Sep 17 00:00:00 2001
From: Nicholas Ward <npward@berkeley.edu>
Date: Wed, 12 Apr 2023 09:34:53 -0700
Subject: [PATCH] deterministic build function

---
 plonky2/examples/fibonacci.rs        |  2 +-
 plonky2/src/plonk/circuit_builder.rs | 26 ++++++++++++++++++++++++--
 plonky2/src/plonk/get_challenges.rs  |  2 +-
 3 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/plonky2/examples/fibonacci.rs b/plonky2/examples/fibonacci.rs
index aa20c0ff..6766c2b2 100644
--- a/plonky2/examples/fibonacci.rs
+++ b/plonky2/examples/fibonacci.rs
@@ -42,7 +42,7 @@ fn main() -> Result<()> {
     pw.set_target(initial_a, F::ZERO);
     pw.set_target(initial_b, F::ONE);
 
-    let data = builder.build::<C>();
+    let data = builder.build_deterministic::<C>();
 
     let common_circuit_data_serialized = serde_json::to_string(&data.common).unwrap();
     fs::write("common_circuit_data.json", common_circuit_data_serialized).expect("Unable to write file");
diff --git a/plonky2/src/plonk/circuit_builder.rs b/plonky2/src/plonk/circuit_builder.rs
index 29a38047..a0f43602 100644
--- a/plonky2/src/plonk/circuit_builder.rs
+++ b/plonky2/src/plonk/circuit_builder.rs
@@ -737,8 +737,10 @@ impl<F: RichField + Extendable<D>, const D: usize> CircuitBuilder<F, D> {
         }
     }
 
+    /// Standard build.
+
     /// Builds a "full circuit", with both prover and verifier data.
-    pub fn build<C: GenericConfig<D, F = F>>(mut self) -> CircuitData<F, C, D>
+    fn build_inner<C: GenericConfig<D, F = F>>(mut self, deterministic: bool) -> CircuitData<F, C, D>
     where
         [(); C::HCO::WIDTH]:,
         [(); C::HCI::WIDTH]:,
@@ -762,7 +764,9 @@ impl<F: RichField + Extendable<D>, const D: usize> CircuitBuilder<F, D> {
         {
             self.connect(hash_part, Target::wire(pi_gate, wire))
         }
-        // self.randomize_unused_pi_wires(pi_gate);
+        if !deterministic {
+            self.randomize_unused_pi_wires(pi_gate);
+        }
 
         // Make sure we have enough constant generators. If not, add a `ConstantGate`.
         while self.constants_to_targets.len() > self.constant_generators.len() {
@@ -945,6 +949,24 @@ impl<F: RichField + Extendable<D>, const D: usize> CircuitBuilder<F, D> {
         }
     }
 
+    /// Standard build.    
+    pub fn build<C: GenericConfig<D, F = F>>(self) -> CircuitData<F, C, D>
+    where
+        [(); C::HCO::WIDTH]:,
+        [(); C::HCI::WIDTH]:,
+    {
+        self.build_inner(false)
+    }
+
+    /// Build without randomizing PI wires
+    pub fn build_deterministic<C: GenericConfig<D, F = F>>(self) -> CircuitData<F, C, D>
+    where
+        [(); C::HCO::WIDTH]:,
+        [(); C::HCI::WIDTH]:,
+    {
+        self.build_inner(true)
+    }
+
     /// Builds a "prover circuit", with data needed to generate proofs but not verify them.
     pub fn build_prover<C: GenericConfig<D, F = F>>(self) -> ProverCircuitData<F, C, D>
     where
diff --git a/plonky2/src/plonk/get_challenges.rs b/plonky2/src/plonk/get_challenges.rs
index 0e90b398..d0682572 100644
--- a/plonky2/src/plonk/get_challenges.rs
+++ b/plonky2/src/plonk/get_challenges.rs
@@ -94,7 +94,7 @@ impl<F: RichField + Extendable<D>, C: GenericConfig<D, F = F>, const D: usize>
     }
 
     /// Computes all Fiat-Shamir challenges used in the Plonk proof.
-    pub fn get_challenges(
+    pub(crate) fn get_challenges(
         &self,
         public_inputs_hash: <<C as GenericConfig<D>>::InnerHasher as Hasher<F, C::HCI>>::Hash,
         circuit_digest: &<<C as GenericConfig<D>>::Hasher as Hasher<C::F, C::HCO>>::Hash,