From ec39e03b10e242421d2dc3ca4dcfa623fd8a7fed Mon Sep 17 00:00:00 2001
From: M Alghazwi <m.ghazwi@gmail.com>
Date: Tue, 27 May 2025 10:27:40 +0200
Subject: [PATCH] add observe the FRI config in the challenger

---
 verifier/util.go     |  7 +++++++
 verifier/verifier.go | 21 +++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/verifier/util.go b/verifier/util.go
index 150ada5..e7525ae 100644
--- a/verifier/util.go
+++ b/verifier/util.go
@@ -22,3 +22,10 @@ func (c *ExampleVerifierCircuit) Define(api frontend.API) error {
 
 	return nil
 }
+
+func boolToUint64(b bool) uint64 {
+	if b {
+		return 1
+	}
+	return 0
+}
diff --git a/verifier/verifier.go b/verifier/verifier.go
index 0d47f23..05d5ea3 100644
--- a/verifier/verifier.go
+++ b/verifier/verifier.go
@@ -51,6 +51,27 @@ func (c *VerifierChip) GetChallenges(
 	numChallenges := config.NumChallenges
 	challenger := challenger.NewChip(c.api)
 
+	// observe the FRI config
+	var friParams = c.commonData.FriParams
+	var friConfig = friParams.Config
+	challenger.ObserveElement(gl.NewVariable(friConfig.RateBits))
+	challenger.ObserveElement(gl.NewVariable(friConfig.CapHeight))
+	challenger.ObserveElement(gl.NewVariable(friConfig.ProofOfWorkBits))
+	// here we fix the reduction strategy to the standard one:
+	// reduction_strategy: FriReductionStrategy::ConstantArityBits(4, 5)
+	// this is serialized as [1,4,5]
+	// TODO: make this work for all reduction strategies
+	challenger.ObserveElement(gl.One())
+	challenger.ObserveElement(gl.NewVariable(4))
+	challenger.ObserveElement(gl.NewVariable(5))
+	challenger.ObserveElement(gl.NewVariable(friConfig.NumQueryRounds))
+	var hide uint64 = boolToUint64(friParams.Hiding)
+	challenger.ObserveElement(gl.NewVariable(hide))
+	challenger.ObserveElement(gl.NewVariable(friParams.DegreeBits))
+	for _, arity := range friParams.ReductionArityBits {
+		challenger.ObserveElement(gl.NewVariable(arity))
+	}
+
 	var circuitDigest = verifierData.CircuitDigest
 
 	challenger.ObserveBN254Hash(circuitDigest)