fix: graceful failures in verifier code paths + other fixes

barretenberg/cpp/src/barretenberg/bbapi/bbapi_chonk.cpp

@@ -28,8 +28,14 @@ ChonkStart::Response ChonkStart::execute(BBApiRequest& request) &&
     BB_BENCH_NAME(MSGPACK_SCHEMA_NAME);
 
     request.ivc_in_progress = std::make_shared<Chonk>(num_circuits);
-
     request.ivc_stack_depth = 0;
+
+    // Clear any stale loaded-circuit state from a previous session so that
+    // ChonkAccumulate cannot silently reuse a circuit loaded before this ChonkStart.
+    request.loaded_circuit_name.clear();
+    request.loaded_circuit_constraints.reset();
+    request.loaded_circuit_vk.clear();
+
     return Response{};
 }
 
@@ -63,6 +69,15 @@ ChonkAccumulate::Response ChonkAccumulate::execute(BBApiRequest& request) &&
     acir_format::WitnessVector witness_data = acir_format::witness_buf_to_witness_vector(std::move(witness));
     acir_format::AcirProgram program{ std::move(request.loaded_circuit_constraints.value()), std::move(witness_data) };
 
+    // Clear loaded state immediately after moving out of it. This ensures that if any subsequent
+    // step throws, the request won't appear to still have a valid circuit loaded (the optional
+    // would be in a moved-from state, which is technically has_value()==true but poisoned).
+    auto loaded_vk = std::move(request.loaded_circuit_vk);
+    auto circuit_name = std::move(request.loaded_circuit_name);
+    request.loaded_circuit_constraints.reset();
+    request.loaded_circuit_vk.clear();
+    request.loaded_circuit_name.clear();
+
     const acir_format::ProgramMetadata metadata{ .ivc = request.ivc_in_progress };
     auto circuit = acir_format::create_circuit<IVCBase::ClientCircuit>(program, metadata);
 
@@ -71,17 +86,17 @@ ChonkAccumulate::Response ChonkAccumulate::execute(BBApiRequest& request) &&
     if (request.vk_policy == VkPolicy::RECOMPUTE) {
         precomputed_vk = nullptr;
     } else if (request.vk_policy == VkPolicy::DEFAULT || request.vk_policy == VkPolicy::CHECK) {
-        if (!request.loaded_circuit_vk.empty()) {
-            validate_vk_size<Chonk::MegaVerificationKey>(request.loaded_circuit_vk);
-            precomputed_vk = from_buffer<std::shared_ptr<Chonk::MegaVerificationKey>>(request.loaded_circuit_vk);
+        if (!loaded_vk.empty()) {
+            validate_vk_size<Chonk::MegaVerificationKey>(loaded_vk);
+            precomputed_vk = from_buffer<std::shared_ptr<Chonk::MegaVerificationKey>>(loaded_vk);
 
             if (request.vk_policy == VkPolicy::CHECK) {
                 auto prover_instance = std::make_shared<Chonk::ProverInstance>(circuit);
                 auto computed_vk = std::make_shared<Chonk::MegaVerificationKey>(prover_instance->get_precomputed());
 
                 // Dereference to compare VK contents
                 if (*precomputed_vk != *computed_vk) {
-                    throw_or_abort("VK check failed for circuit '" + request.loaded_circuit_name +
+                    throw_or_abort("VK check failed for circuit '" + circuit_name +
                                    "': provided VK does not match computed VK");
                 }
             }
@@ -90,16 +105,13 @@ ChonkAccumulate::Response ChonkAccumulate::execute(BBApiRequest& request) &&
         throw_or_abort("Invalid VK policy. Valid options: default, check, recompute");
     }
 
-    info("ChonkAccumulate - accumulating circuit '", request.loaded_circuit_name, "'");
+    info("ChonkAccumulate - accumulating circuit '", circuit_name, "'");
     if (detail::use_memory_profile) {
-        detail::GLOBAL_MEMORY_PROFILE.set_circuit_name(request.loaded_circuit_name);
+        detail::GLOBAL_MEMORY_PROFILE.set_circuit_name(circuit_name);
     }
     request.ivc_in_progress->accumulate(circuit, precomputed_vk);
     request.ivc_stack_depth++;
 
-    request.loaded_circuit_constraints.reset();
-    request.loaded_circuit_vk.clear();
-
     return Response{};
 }
 

barretenberg/cpp/src/barretenberg/chonk/batched_honk_translator/batched_honk_translator_verifier.cpp

@@ -44,6 +44,9 @@ typename BatchedHonkTranslatorVerifier_<Curve>::OinkResult BatchedHonkTranslator
     mega_zk_verifier_instance = std::make_shared<MegaZKVerifierInstance>(mega_zk_vk_and_hash);
 
     // Derive num_public_inputs from the Oink-only MegaZK proof.
+    if (mega_zk_proof.size() < ProofLength::Oink<MegaZKFlavorT>::LENGTH_WITHOUT_PUB_INPUTS) {
+        throw_or_abort("MegaZK Oink proof too short to derive num_public_inputs");
+    }
     const size_t num_public_inputs = mega_zk_proof.size() - ProofLength::Oink<MegaZKFlavorT>::LENGTH_WITHOUT_PUB_INPUTS;
 
     OinkVerifier<MegaZKFlavorT> oink_verifier{ mega_zk_verifier_instance, transcript, num_public_inputs };

barretenberg/cpp/src/barretenberg/chonk/chonk.cpp

@@ -732,7 +732,7 @@ void Chonk::update_native_verifier_accumulator(const VerifierInputs& queue_entry
         info("Chonk accumulate: hash of verifier accumulator computed natively set in previous kernel IO: ",
              native_verifier_accum_hash);
     }
-    has_last_app_been_accumulated = num_circuits_accumulated + 1 == num_circuits - 4;
+    has_last_app_been_accumulated = num_circuits_accumulated + 1 == num_circuits - 3;
     is_previous_circuit_a_kernel = queue_entry.is_kernel;
 
     info("======= END OF DEBUGGING INFO FOR NATIVE FOLDING STEP =======");

barretenberg/cpp/src/barretenberg/chonk/chonk.test.cpp

@@ -449,8 +449,9 @@ TEST_F(ChonkTests, MsgpackProofFromFileOrBuffer)
         std::generate(random_bytes.begin(), random_bytes.end(), []() { return static_cast<uint8_t>(rand() % 256); });
         std::copy(random_bytes.begin(), random_bytes.end(), buffer.data());
 
-        // Expect deserialization to fail with error msgpack::v1::type_error with description "std::bad_cast"
-        EXPECT_THROW(ChonkProof::from_msgpack_buffer(buffer), msgpack::v1::type_error);
+        // Expect deserialization to fail (either msgpack parse error, type mismatch, trailing data,
+        // or non-canonical field encoding)
+        EXPECT_ANY_THROW(ChonkProof::from_msgpack_buffer(buffer));
     }
 };
 

barretenberg/cpp/src/barretenberg/chonk/chonk_proof.cpp

@@ -44,7 +44,9 @@ ChonkProof_<IsRecursive> ChonkProof_<IsRecursive>::from_field_elements(const std
     // MegaZK Oink proof size = total - all other fixed-size components.
     // This correctly accounts for any ACIR public inputs prepended to the oink portion.
     constexpr size_t fixed_total = merge_size + eccvm_size + ipa_size + joint_size;
-    BB_ASSERT_GTE(fields.size(), fixed_total, "ChonkProof::from_field_elements: proof too short");
+    if (fields.size() < fixed_total) {
+        throw_or_abort("ChonkProof::from_field_elements: proof too short");
+    }
     const size_t mega_zk_oink_length = fields.size() - fixed_total;
 
     auto it = fields.begin();

barretenberg/cpp/src/barretenberg/chonk/chonk_proof.hpp

@@ -124,10 +124,14 @@ template <bool IsRecursive = false> struct ChonkProof_ {
     static ChonkProof_ from_msgpack_buffer(const msgpack::sbuffer& buffer)
         requires(!IsRecursive)
     {
-        msgpack::object_handle oh = msgpack::unpack(buffer.data(), buffer.size());
-        msgpack::object obj = oh.get();
+        std::size_t offset = 0;
+        msgpack::object_handle oh = msgpack::unpack(buffer.data(), buffer.size(), offset);
+        if (offset != buffer.size()) {
+            throw_or_abort("ChonkProof::from_msgpack_buffer: trailing data (" + std::to_string(buffer.size() - offset) +
+                           " extra bytes)");
+        }
         ChonkProof_ proof;
-        obj.convert(proof);
+        oh.get().convert(proof);
         return proof;
     }
 

barretenberg/cpp/src/barretenberg/chonk/proof_compression.hpp

@@ -59,7 +59,9 @@ class ProofCompressor {
 
     static uint256_t read_u256(const std::vector<uint8_t>& data, size_t& pos)
     {
-        BB_ASSERT(pos + 32 <= data.size());
+        if (pos + 32 > data.size()) {
+            throw_or_abort("proof_compression: read_u256 out of bounds");
+        }
         uint256_t val{ 0, 0, 0, 0 };
         for (int i = 31; i >= 0; --i) {
             val.data[i / 8] |= static_cast<uint64_t>(data[pos++]) << (8 * (i % 8));
@@ -423,10 +425,14 @@ class ProofCompressor {
      */
     static size_t compressed_mega_num_public_inputs(size_t compressed_bytes)
     {
-        BB_ASSERT(compressed_bytes % 32 == 0);
+        if (compressed_bytes % 32 != 0) {
+            throw_or_abort("proof_compression: compressed size not aligned to 32 bytes");
+        }
         size_t total_elements = compressed_bytes / 32;
         size_t fixed_elements = compressed_element_count(0);
-        BB_ASSERT(total_elements >= fixed_elements);
+        if (total_elements < fixed_elements) {
+            throw_or_abort("proof_compression: compressed proof too short");
+        }
         return total_elements - fixed_elements;
     }
 
@@ -493,7 +499,9 @@ class ProofCompressor {
         size_t mega_num_pub_inputs =
             proof.hiding_oink_proof.size() - ProofLength::Oink<MegaZKFlavor>::LENGTH_WITHOUT_PUB_INPUTS;
         walk_chonk_proof(bn254_scalar, bn254_comm, grumpkin_scalar, grumpkin_comm, mega_num_pub_inputs);
-        BB_ASSERT(offset == flat.size());
+        if (offset != flat.size()) {
+            throw_or_abort("proof_compression: compress did not consume all proof elements");
+        }
         return out;
     }
 
@@ -505,7 +513,9 @@ class ProofCompressor {
         // BN254 callbacks
         auto bn254_scalar = [&]() {
             uint256_t raw = read_u256(compressed, pos);
-            BB_ASSERT(raw < Fr::modulus);
+            if (raw >= Fr::modulus) {
+                throw_or_abort("proof_compression: BN254 scalar out of range");
+            }
             flat.emplace_back(raw);
         };
 
@@ -523,11 +533,15 @@ class ProofCompressor {
                 return;
             }
 
-            BB_ASSERT(x_val < Fq::modulus);
+            if (x_val >= Fq::modulus) {
+                throw_or_abort("proof_compression: BN254 x-coordinate out of range");
+            }
             Fq x(x_val);
             Fq y_squared = x * x * x + Bn254G1Params::b;
             auto [is_square, y] = y_squared.sqrt();
-            BB_ASSERT(is_square);
+            if (!is_square) {
+                throw_or_abort("proof_compression: BN254 point not on curve");
+            }
 
             if (y_is_negative(y) != sign) {
                 y = -y;
@@ -555,11 +569,15 @@ class ProofCompressor {
                 return;
             }
 
-            BB_ASSERT(x_val < Fr::modulus);
+            if (x_val >= Fr::modulus) {
+                throw_or_abort("proof_compression: Grumpkin x-coordinate out of range");
+            }
             Fr x(x_val);
             Fr y_squared = x * x * x + grumpkin::G1Params::b;
             auto [is_square, y] = y_squared.sqrt();
-            BB_ASSERT(is_square);
+            if (!is_square) {
+                throw_or_abort("proof_compression: Grumpkin point not on curve");
+            }
 
             if (y_is_negative(y) != sign) {
                 y = -y;
@@ -571,15 +589,19 @@ class ProofCompressor {
 
         auto grumpkin_scalar = [&]() {
             uint256_t raw = read_u256(compressed, pos);
-            BB_ASSERT(raw < Fq::modulus);
+            if (raw >= Fq::modulus) {
+                throw_or_abort("proof_compression: Grumpkin scalar out of range");
+            }
             Fq fq_val(raw);
             auto [lo, hi] = split_fq(fq_val);
             flat.emplace_back(lo);
             flat.emplace_back(hi);
         };
 
         walk_chonk_proof(bn254_scalar, bn254_comm, grumpkin_scalar, grumpkin_comm, mega_num_public_inputs);
-        BB_ASSERT(pos == compressed.size());
+        if (pos != compressed.size()) {
+            throw_or_abort("proof_compression: decompression did not consume all bytes");
+        }
         return ChonkProof::from_field_elements(flat);
     }
 };

barretenberg/cpp/src/barretenberg/commitment_schemes/ipa/ipa.hpp

@@ -475,6 +475,7 @@ template <typename Curve_, size_t log_poly_length = CONST_ECCVM_LOG_N> class IPA
                 scalar_multiplication::pippenger_unsafe<Curve>(data.s_vec, { &srs_elements[0], /*size*/ poly_length });
         }
         if (G_zero != data.G_zero_from_prover) {
+            info("IPA verification failed: G_0 mismatch");
             return false;
         }
 
@@ -669,8 +670,14 @@ template <typename Curve_, size_t log_poly_length = CONST_ECCVM_LOG_N> class IPA
         requires(!Curve::is_stdlib_type)
     {
         const size_t num_claims = opening_claims.size();
-        BB_ASSERT(num_claims == transcripts.size());
-        BB_ASSERT(num_claims > 0);
+        if (num_claims != transcripts.size()) {
+            info("IPA batch verification failed: claims/transcripts size mismatch");
+            return false;
+        }
+        if (num_claims == 0) {
+            info("IPA batch verification failed: no claims provided");
+            return false;
+        }
 
         // Phase 1: Per-proof transcript processing (sequential, each proof is cheap)
         std::vector<GroupElement> C_zeros(num_claims);
@@ -770,6 +777,12 @@ template <typename Curve_, size_t log_poly_length = CONST_ECCVM_LOG_N> class IPA
     static bool full_verify_recursive(const VK& vk, const OpeningClaim<Curve>& opening_claim, auto& transcript)
         requires Curve::is_stdlib_type
     {
+        // Check SRS size up front before any circuit construction
+        if (vk.get_monomial_points().size() < poly_length) {
+            throw_or_abort("IPA recursive verification: not enough SRS points (need " + std::to_string(poly_length) +
+                           ", have " + std::to_string(vk.get_monomial_points().size()) + ")");
+        }
+
         add_claim_to_hash_buffer(opening_claim, transcript);
         VerifierAccumulator verifier_accumulator = reduce_verify_internal_recursive(opening_claim, transcript);
         auto round_challenges_inv = verifier_accumulator.u_challenges_inv;
@@ -806,7 +819,6 @@ template <typename Curve_, size_t log_poly_length = CONST_ECCVM_LOG_N> class IPA
         // Compute G_zero
         // In the native verifier, this uses pippenger. Here we use batch_mul.
         std::vector<Commitment> srs_elements = vk.get_monomial_points();
-        BB_ASSERT_GTE(srs_elements.size(), poly_length, "Not enough SRS points for IPA!");
         srs_elements.resize(poly_length);
         Commitment computed_G_zero = Commitment::batch_mul(srs_elements, s_vec);
         // check the computed G_zero and the claimed G_zero are the same.

barretenberg/cpp/src/barretenberg/commitment_schemes/kzg/kzg.hpp

@@ -151,7 +151,11 @@ template <typename Curve_> class KZG {
 
         // Validate the final MSM size if expected size is provided
         if (expected_final_msm_size != 0) {
-            BB_ASSERT_EQ(batch_opening_claim.commitments.size(), expected_final_msm_size);
+            if (batch_opening_claim.commitments.size() != expected_final_msm_size) {
+                throw_or_abort("KZG verification: unexpected final MSM size " +
+                               std::to_string(batch_opening_claim.commitments.size()) + " (expected " +
+                               std::to_string(expected_final_msm_size) + ")");
+            }
         }
 
         // Compute C + [W]₁ ⋅ z

barretenberg/cpp/src/barretenberg/commitment_schemes/shplonk/shplemini.hpp

@@ -371,7 +371,9 @@ template <typename Curve, bool HasZK = false> class ShpleminiVerifier_ {
         // Used in ECCVM and BatchedHonkTranslator. The nu power offset in batch_sumcheck_round_claims
         // assumes ZK claims (NUM_SMALL_IPA_EVALUATIONS) precede sumcheck round claims in the batching order.
         if (committed_sumcheck) {
-            BB_ASSERT(HasZK, "committed sumcheck requires ZK for correct nu power indexing");
+            if constexpr (!HasZK) {
+                throw_or_abort("Shplemini: committed sumcheck requires ZK for correct nu power indexing");
+            }
             batch_sumcheck_round_claims(commitments,
                                         scalars,
                                         constant_term_accumulator,
@@ -522,10 +524,11 @@ template <typename Curve, bool HasZK = false> class ShpleminiVerifier_ {
                 // next duplicate; the original at original_start + i is unaffected since
                 // we erase higher-index ranges first.
                 if constexpr (!Curve::is_stdlib_type) {
-                    BB_ASSERT(commitments[duplicate_start] == commitments[original_start + i],
-                              "remove_repeated_commitments: commitment mismatch at duplicate index " +
-                                  std::to_string(duplicate_start) + " vs original index " +
-                                  std::to_string(original_start + i));
+                    if (commitments[duplicate_start] != commitments[original_start + i]) {
+                        throw_or_abort("remove_repeated_commitments: commitment mismatch at duplicate index " +
+                                       std::to_string(duplicate_start) + " vs original index " +
+                                       std::to_string(original_start + i));
+                    }
                 }
                 scalars.erase(scalars.begin() + static_cast<std::ptrdiff_t>(duplicate_start));
                 commitments.erase(commitments.begin() + static_cast<std::ptrdiff_t>(duplicate_start));

barretenberg/cpp/src/barretenberg/commitment_schemes/shplonk/shplonk.hpp

@@ -359,7 +359,9 @@ template <typename Curve> class ShplonkVerifier_ {
         , commitments({ quotient })
         , scalars{ Fr{ 1 } }
     {
-        BB_ASSERT_GT(num_claims, 1U, "Using Shplonk with just one claim. Should use batch reduction.");
+        if (num_claims <= 1U) {
+            throw_or_abort("Using Shplonk with just one claim. Should use batch reduction.");
+        }
         const size_t num_commitments = commitments.size();
         commitments.reserve(num_commitments);
         scalars.reserve(num_commitments);

barretenberg/cpp/src/barretenberg/ecc/fields/field_impl.hpp

@@ -830,8 +830,13 @@ template <class Params> void field<Params>::msgpack_unpack(auto o)
         data[i] = reversed[i];
     }
 
+    // Reject non-canonical field encodings (values >= modulus) to ensure strict parsing.
+    if (uint256_t{ data[0], data[1], data[2], data[3] } >= modulus) {
+        throw_or_abort("msgpack field deserialization: non-canonical encoding (value >= modulus)");
+    }
+
     // Finally, the field is converted back to Montgomery form, just like in the old format.
-    *this = to_montgomery_form_reduced();
+    *this = to_montgomery_form();
 }
 
 } // namespace bb

barretenberg/cpp/src/barretenberg/ecc/fields/prime_field.test.cpp

@@ -615,6 +615,46 @@ TYPED_TEST(PrimeFieldTest, Msgpack)
     EXPECT_EQ(actual, expected);
 }
 
+TYPED_TEST(PrimeFieldTest, MsgpackRejectsNonCanonical)
+{
+    using F = TypeParam;
+
+    // Use a small value so that (value + modulus) is guaranteed to fit in 256 bits,
+    // even for fields with moduli close to 2^256 (e.g., secp256k1, secp256r1).
+    F a = F(1);
+    msgpack::sbuffer buffer;
+    msgpack::pack(buffer, a);
+
+    // Find the 32-byte binary payload inside the msgpack buffer.
+    // pack_bin(32) produces: 0xc4 0x20 <32 bytes>
+    uint8_t* buf = reinterpret_cast<uint8_t*>(buffer.data());
+    size_t buf_size = buffer.size();
+    uint8_t* field_bytes = nullptr;
+    for (size_t i = 0; i + 33 <= buf_size; i++) {
+        if (buf[i] == 0xc4 && buf[i + 1] == 0x20) {
+            field_bytes = &buf[i + 2];
+            break;
+        }
+    }
+    ASSERT_NE(field_bytes, nullptr) << "Could not find 32-byte bin payload in msgpack buffer";
+
+    // Replace the payload with (1 + modulus), a non-canonical encoding of 1.
+    uint256_t non_canonical = uint256_t(1) + F::modulus;
+    for (int i = 31; i >= 0; i--) {
+        field_bytes[i] = static_cast<uint8_t>(non_canonical.data[0] & 0xFF);
+        non_canonical >>= 8;
+    }
+
+    // Deserializing the mutated buffer must throw
+    EXPECT_THROW(
+        {
+            msgpack::object_handle oh = msgpack::unpack(buffer.data(), buffer.size());
+            F result;
+            oh.get().convert(result);
+        },
+        std::runtime_error);
+}
+
 // ================================
 // Montgomery Form Conversion Tests (254-bit fields)
 // ================================