From e091325e8fc700fe8d6432ef606e4687a06a1e63 Mon Sep 17 00:00:00 2001
From: Suyash Bagad <suyashnbagad1997@gmail.com>
Date: Sat, 25 Mar 2023 08:30:18 +0000
Subject: [PATCH 1/2] Add `contains_recursive_proof` to recursive vk.

---
 .../stdlib/recursion/verification_key/verification_key.hpp    | 4 ++++
 cpp/src/barretenberg/stdlib/recursion/verifier/verifier.hpp   | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/cpp/src/barretenberg/stdlib/recursion/verification_key/verification_key.hpp b/cpp/src/barretenberg/stdlib/recursion/verification_key/verification_key.hpp
index d5169518bd..4714233f1c 100644
--- a/cpp/src/barretenberg/stdlib/recursion/verification_key/verification_key.hpp
+++ b/cpp/src/barretenberg/stdlib/recursion/verification_key/verification_key.hpp
@@ -259,6 +259,10 @@ template <typename Curve> struct verification_key {
     field_t<Composer> num_public_inputs;
     field_t<Composer> z_pow_n;
 
+    // NOTE: This does not strictly need to be a circuit type. It can be used to check in the circuit
+    // if a proof contains any aggregated state.
+    bool_t<Composer> contains_recursive_proof;
+
     evaluation_domain<Composer> domain;
 
     std::map<std::string, typename Curve::g1_ct> commitments;
diff --git a/cpp/src/barretenberg/stdlib/recursion/verifier/verifier.hpp b/cpp/src/barretenberg/stdlib/recursion/verifier/verifier.hpp
index 5802ad8f75..429eafa915 100644
--- a/cpp/src/barretenberg/stdlib/recursion/verifier/verifier.hpp
+++ b/cpp/src/barretenberg/stdlib/recursion/verifier/verifier.hpp
@@ -352,6 +352,10 @@ recursion_output<Curve> verify_proof(typename Curve::Composer* context,
         rhs_scalars.push_back(random_separator);
     }
 
+    // Check if recursive proof information is correctly set.
+    key->contains_recursive_proof.assert_equal(key->base_key->contains_recursive_proof,
+                                               "contains_recursive_proof is incorrectly set");
+
     /**
      * N.B. if this key contains a recursive proof, then ALL potential verification keys being verified by the outer
      *circuit must ALSO contain a recursive proof (this is not a concern if the key is being generated from circuit

From 81d82430e048e80b0ebbb59e8354dac2e919d2d3 Mon Sep 17 00:00:00 2001
From: Suyash Bagad <suyashnbagad1997@gmail.com>
Date: Sat, 25 Mar 2023 09:19:16 +0000
Subject: [PATCH 2/2] Fix constructors.

---
 .../stdlib/recursion/verification_key/verification_key.hpp      | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/cpp/src/barretenberg/stdlib/recursion/verification_key/verification_key.hpp b/cpp/src/barretenberg/stdlib/recursion/verification_key/verification_key.hpp
index 4714233f1c..4d9bc421eb 100644
--- a/cpp/src/barretenberg/stdlib/recursion/verification_key/verification_key.hpp
+++ b/cpp/src/barretenberg/stdlib/recursion/verification_key/verification_key.hpp
@@ -120,6 +120,7 @@ template <typename Curve> struct verification_key {
         key->n = witness_t<Composer>(ctx, barretenberg::fr(input_key->circuit_size));
         key->num_public_inputs = witness_t<Composer>(ctx, input_key->num_public_inputs);
         key->domain = evaluation_domain<Composer>::from_witness(ctx, input_key->domain);
+        key->contains_recursive_proof = witness_t<Composer>(ctx, input_key->contains_recursive_proof);
 
         for (const auto& [tag, value] : input_key->commitments) {
             key->commitments.insert({ tag, Curve::g1_ct::from_witness(ctx, value) });
@@ -136,6 +137,7 @@ template <typename Curve> struct verification_key {
         key->base_key = input_key;
         key->n = field_t<Composer>(ctx, input_key->circuit_size);
         key->num_public_inputs = field_t<Composer>(ctx, input_key->num_public_inputs);
+        key->contains_recursive_proof = bool_t<Composer>(ctx, input_key->contains_recursive_proof);
 
         key->domain = evaluation_domain<Composer>::from_constants(ctx, input_key->domain);