From 2e6480a97fb11e29b25f5e808e3d674a10682ed3 Mon Sep 17 00:00:00 2001
From: Nicholas Ward <npward@berkeley.edu>
Date: Wed, 21 Sep 2022 15:41:14 -0700
Subject: [PATCH] Fibonacci example

---
 plonky2/examples/fibonacci.rs | 39 +++++++++++++++++++++++++++++++++++
 plonky2/src/plonk/verifier.rs |  2 +-
 2 files changed, 40 insertions(+), 1 deletion(-)
 create mode 100644 plonky2/examples/fibonacci.rs

diff --git a/plonky2/examples/fibonacci.rs b/plonky2/examples/fibonacci.rs
new file mode 100644
index 00000000..4f968178
--- /dev/null
+++ b/plonky2/examples/fibonacci.rs
@@ -0,0 +1,39 @@
+use anyhow::Result;
+use plonky2::iop::witness::PartialWitness;
+use plonky2::plonk::circuit_builder::CircuitBuilder;
+use plonky2::plonk::circuit_data::CircuitConfig;
+use plonky2::plonk::config::{GenericConfig, PoseidonGoldilocksConfig};
+use plonky2::field::types::Field;
+use plonky2::plonk::verifier::verify;
+
+fn main() -> Result<()> {
+    const D: usize = 2;
+    type C = PoseidonGoldilocksConfig;
+    type F = <C as GenericConfig<D>>::F;
+
+    let config = CircuitConfig::standard_recursion_config();
+
+    let pw = PartialWitness::new();
+    let mut builder = CircuitBuilder::<F, D>::new(config);
+
+    let zero_target = builder.zero();
+    let one_target = builder.one();
+    let mut prev_target = zero_target;
+    let mut cur_target = one_target;
+    for _ in 0..99 {
+        let temp = builder.add(prev_target, cur_target);
+        prev_target = cur_target;
+        cur_target = temp;
+    }
+
+    let fib_100 = F::from_canonical_u64(3736710860384812976);
+    let fib_100_target = builder.constant(fib_100);
+
+    builder.connect(fib_100_target, cur_target);
+
+    let data = builder.build::<C>();
+
+    let proof = data.prove(pw)?;
+
+    verify(proof, &data.verifier_only, &data.common)
+}
diff --git a/plonky2/src/plonk/verifier.rs b/plonky2/src/plonk/verifier.rs
index 6a4f3790..5a3f6a94 100644
--- a/plonky2/src/plonk/verifier.rs
+++ b/plonky2/src/plonk/verifier.rs
@@ -12,7 +12,7 @@ use crate::plonk::validate_shape::validate_proof_with_pis_shape;
 use crate::plonk::vanishing_poly::eval_vanishing_poly;
 use crate::plonk::vars::EvaluationVars;
 
-pub(crate) fn verify<F: RichField + Extendable<D>, C: GenericConfig<D, F = F>, const D: usize>(
+pub fn verify<F: RichField + Extendable<D>, C: GenericConfig<D, F = F>, const D: usize>(
     proof_with_pis: ProofWithPublicInputs<F, C, D>,
     verifier_data: &VerifierOnlyCircuitData<C, D>,
     common_data: &CommonCircuitData<F, C, D>,