lousy_test.diff

diff --git a/src/gtest/test_proofs.cpp b/src/gtest/test_proofs.cpp
index 49202f1f6..0d678a414 100644
--- a/src/gtest/test_proofs.cpp
+++ b/src/gtest/test_proofs.cpp
@@ -3,6 +3,7 @@
 
 #include <iostream>
 
+#include "algebra/knowledge_commitment/knowledge_commitment.hpp"
 #include "libsnark/common/default_types/r1cs_ppzksnark_pp.hpp"
 #include "libsnark/zk_proof_systems/ppzksnark/r1cs_ppzksnark/r1cs_ppzksnark.hpp"
 #include "zk_proof_systems/ppzksnark/r1cs_ppzksnark/r1cs_ppzksnark.hpp"
@@ -394,9 +395,10 @@ TEST(proofs, g2_serializes_properly)
 
 TEST(proofs, zksnark_serializes_properly)
 {
+    std::vector<libsnark::knowledge_commitment<curve_G1, curve_G1> > zeroed_out_a_query;
     auto example = libsnark::generate_r1cs_example_with_field_input<curve_Fr>(250, 4);
     example.constraint_system.swap_AB_if_beneficial();
-    auto kp = libsnark::r1cs_ppzksnark_generator<curve_pp>(example.constraint_system);
+    auto kp = libsnark::r1cs_ppzksnark_generator<curve_pp>(example.constraint_system, &zeroed_out_a_query);
     auto vkprecomp = libsnark::r1cs_ppzksnark_verifier_process_vk(kp.vk);
 
     for (size_t i = 0; i < 20; i++) {
@@ -471,6 +473,36 @@ TEST(proofs, zksnark_serializes_properly)
             newproof
         ));
     }
+
+    // Compute a proof that hands the pairing function a G1 point at infinity,
+    // and make sure the verifier still rejects the proof.
+    {
+        // Construct a valid proof:
+        auto proof = libsnark::r1cs_ppzksnark_prover<curve_pp>(
+            kp.pk,
+            example.primary_input,
+            example.auxiliary_input,
+            example.constraint_system
+        );
+
+        // Compute a new answer to the A query with negative input
+        proof.g_A.g = -(zeroed_out_a_query[0].g);
+        proof.g_A.h = -(zeroed_out_a_query[0].h);
+
+        size_t i = 1;
+        for (curve_Fr in : example.primary_input) {
+            proof.g_A.g = proof.g_A.g + ((-in) * zeroed_out_a_query[i].g);
+            proof.g_A.h = proof.g_A.h + ((-in) * zeroed_out_a_query[i].h);
+
+            i++;
+        }
+
+        ASSERT_FALSE(libsnark::r1cs_ppzksnark_verifier_strong_IC<curve_pp>(
+            kp.vk,
+            example.primary_input,
+            proof
+        ));
+    }
 }
 
 TEST(proofs, g1_deserialization)
diff --git a/src/libsnark/zk_proof_systems/ppzksnark/r1cs_ppzksnark/r1cs_ppzksnark.hpp b/src/libsnark/zk_proof_systems/ppzksnark/r1cs_ppzksnark/r1cs_ppzksnark.hpp
index 36f6c1499..5a975a12d 100644
--- a/src/libsnark/zk_proof_systems/ppzksnark/r1cs_ppzksnark/r1cs_ppzksnark.hpp
+++ b/src/libsnark/zk_proof_systems/ppzksnark/r1cs_ppzksnark/r1cs_ppzksnark.hpp
@@ -368,7 +368,10 @@ public:
  * Given a R1CS constraint system CS, this algorithm produces proving and verification keys for CS.
  */
 template<typename ppT>
-r1cs_ppzksnark_keypair<ppT> r1cs_ppzksnark_generator(const r1cs_ppzksnark_constraint_system<ppT> &cs);
+r1cs_ppzksnark_keypair<ppT> r1cs_ppzksnark_generator(
+    const r1cs_ppzksnark_constraint_system<ppT> &cs,
+    std::vector<knowledge_commitment<G1<ppT>, G1<ppT> > > *zeroed_out_a_query = NULL
+);
 
 template<typename ppT>
 r1cs_ppzksnark_keypair<ppT> r1cs_ppzksnark_generator(
@@ -380,7 +383,8 @@ r1cs_ppzksnark_keypair<ppT> r1cs_ppzksnark_generator(
     const Fr<ppT>& rA,
     const Fr<ppT>& rB,
     const Fr<ppT>& beta,
-    const Fr<ppT>& gamma
+    const Fr<ppT>& gamma,
+    std::vector<knowledge_commitment<G1<ppT>, G1<ppT> > > *zeroed_out_a_query = NULL
 );
 
 /**
diff --git a/src/libsnark/zk_proof_systems/ppzksnark/r1cs_ppzksnark/r1cs_ppzksnark.tcc b/src/libsnark/zk_proof_systems/ppzksnark/r1cs_ppzksnark/r1cs_ppzksnark.tcc
index aeb2bbb85..789a29cc6 100644
--- a/src/libsnark/zk_proof_systems/ppzksnark/r1cs_ppzksnark/r1cs_ppzksnark.tcc
+++ b/src/libsnark/zk_proof_systems/ppzksnark/r1cs_ppzksnark/r1cs_ppzksnark.tcc
@@ -232,7 +232,8 @@ r1cs_ppzksnark_verification_key<ppT> r1cs_ppzksnark_verification_key<ppT>::dummy
 }
 
 template <typename ppT>
-r1cs_ppzksnark_keypair<ppT> r1cs_ppzksnark_generator(const r1cs_ppzksnark_constraint_system<ppT> &cs)
+r1cs_ppzksnark_keypair<ppT> r1cs_ppzksnark_generator(const r1cs_ppzksnark_constraint_system<ppT> &cs,
+                                                     std::vector<knowledge_commitment<G1<ppT>, G1<ppT> > > *zeroed_out_a_query)
 {
     /* draw random element at which the QAP is evaluated */
     const  Fr<ppT> t = Fr<ppT>::random_element();
@@ -245,7 +246,7 @@ r1cs_ppzksnark_keypair<ppT> r1cs_ppzksnark_generator(const r1cs_ppzksnark_constr
         beta = Fr<ppT>::random_element(),
         gamma = Fr<ppT>::random_element();
 
-    return r1cs_ppzksnark_generator<ppT>(cs, t, alphaA, alphaB, alphaC, rA, rB, beta, gamma);
+    return r1cs_ppzksnark_generator<ppT>(cs, t, alphaA, alphaB, alphaC, rA, rB, beta, gamma, zeroed_out_a_query);
 }
 
 template <typename ppT>
@@ -258,7 +259,8 @@ r1cs_ppzksnark_keypair<ppT> r1cs_ppzksnark_generator(
     const Fr<ppT>& rA,
     const Fr<ppT>& rB,
     const Fr<ppT>& beta,
-    const Fr<ppT>& gamma
+    const Fr<ppT>& gamma,
+    std::vector<knowledge_commitment<G1<ppT>, G1<ppT> > > *zeroed_out_a_query
 )
 {
     enter_block("Call to r1cs_ppzksnark_generator");
@@ -328,6 +330,9 @@ r1cs_ppzksnark_keypair<ppT> r1cs_ppzksnark_generator(
     IC_coefficients.reserve(qap_inst.num_inputs() + 1);
     for (size_t i = 0; i < qap_inst.num_inputs() + 1; ++i)
     {
+        if (zeroed_out_a_query) {
+            zeroed_out_a_query->emplace_back((At[i] * rA) * G1<ppT>::one(), (At[i] * rA * alphaA) * G1<ppT>::one());
+        }
         IC_coefficients.emplace_back(At[i]);
         assert(!IC_coefficients[i].is_zero());
         At[i] = Fr<ppT>::zero();