Add new test ensuring functional correctness of client cache state tr…

…ansition

Signed-off-by: Anjan Roy <[email protected]>

tests/test_frodoPIR.cpp

@@ -74,3 +74,89 @@ TEST(FrodoPIR, PrivateInformationRetrieval)
   test_private_information_retrieval<1ul << 16, 32, 10, 1774>(32);
   test_private_information_retrieval<1ul << 20, 32, 9, 1774>(32);
 }
+
+TEST(FrodoPIR, ClientQueryCacheStateTransition)
+{
+  constexpr size_t λ = 128;
+  constexpr size_t db_entry_count = 1ul << 16;
+  constexpr size_t db_entry_byte_len = 32;
+  constexpr size_t mat_element_bitlen = 10;
+  constexpr size_t lwe_dimension = 1774;
+  constexpr size_t parsed_db_column_count = frodoPIR_matrix::get_required_num_columns(db_entry_byte_len, mat_element_bitlen);
+  constexpr size_t db_byte_len = db_entry_count * db_entry_byte_len;
+  constexpr size_t pub_matM_byte_len = frodoPIR_matrix::matrix_t<lwe_dimension, parsed_db_column_count>::get_byte_len();
+  constexpr size_t query_byte_len = frodoPIR_vector::row_vector_t<db_entry_count>::get_byte_len();
+  constexpr size_t response_byte_len = frodoPIR_vector::row_vector_t<parsed_db_column_count>::get_byte_len();
+
+  std::array<uint8_t, λ / std::numeric_limits<uint8_t>::digits> seed_μ{};
+  std::vector<uint8_t> db_bytes(db_byte_len, 0);
+  std::vector<uint8_t> pub_matM_bytes(pub_matM_byte_len, 0);
+  std::vector<uint8_t> query_bytes(query_byte_len, 0);
+  std::vector<uint8_t> response_bytes(response_byte_len, 0);
+  std::vector<uint8_t> db_row_bytes(db_entry_byte_len, 0);
+
+  auto db_bytes_span = std::span<const uint8_t, db_byte_len>(db_bytes);
+  auto pub_matM_bytes_span = std::span<uint8_t, pub_matM_byte_len>(pub_matM_bytes);
+  auto query_bytes_span = std::span<uint8_t, query_byte_len>(query_bytes);
+  auto response_bytes_span = std::span<uint8_t, response_byte_len>(response_bytes);
+  auto db_row_bytes_span = std::span<uint8_t, db_entry_byte_len>(db_row_bytes);
+
+  prng::prng_t prng{};
+
+  prng.read(seed_μ);
+  prng.read(db_bytes);
+
+  auto [server, M] = frodoPIR_server::server_t<λ, db_entry_count, db_entry_byte_len, mat_element_bitlen, lwe_dimension>::setup(seed_μ, db_bytes_span);
+
+  M.to_le_bytes(pub_matM_bytes_span);
+  auto client = frodoPIR_client::client_t<λ, db_entry_count, db_entry_byte_len, mat_element_bitlen, lwe_dimension>::setup(seed_μ, pub_matM_bytes_span);
+
+  constexpr size_t db_first_row_index = 0;
+  constexpr size_t db_second_row_index = db_first_row_index + 1;
+
+  // Before query for specific database row is prepared, attempt to use the query or decode response for the query.
+  EXPECT_FALSE(client.query(db_first_row_index, query_bytes_span));
+  EXPECT_FALSE(client.query(db_second_row_index, query_bytes_span));
+  EXPECT_FALSE(client.process_response(db_first_row_index, response_bytes_span, db_row_bytes_span));
+  EXPECT_FALSE(client.process_response(db_second_row_index, response_bytes_span, db_row_bytes_span));
+
+  // Prepare query for a specific database row.
+  EXPECT_TRUE(client.prepare_query(db_first_row_index, prng));
+  // Retry preparing query for the same database row.
+  EXPECT_FALSE(client.prepare_query(db_first_row_index, prng));
+
+  // Prepare query for a different database row.
+  EXPECT_TRUE(client.prepare_query(db_second_row_index, prng));
+  // Retry preparing query for same database row.
+  EXPECT_FALSE(client.prepare_query(db_second_row_index, prng));
+
+  // Attempt processing response for specific database row even though query for that row is not yet sent.
+  EXPECT_FALSE(client.process_response(db_first_row_index, response_bytes_span, db_row_bytes_span));
+  EXPECT_FALSE(client.process_response(db_second_row_index, response_bytes_span, db_row_bytes_span));
+
+  // Finalize query for specific database row.
+  EXPECT_TRUE(client.query(db_first_row_index, query_bytes_span));
+  // Retry finalizing query for same database row.
+  EXPECT_FALSE(client.query(db_first_row_index, query_bytes_span));
+
+  // Finalize query for different database row.
+  EXPECT_TRUE(client.query(db_second_row_index, query_bytes_span));
+  // Retry finalizing query for same database row.
+  EXPECT_FALSE(client.query(db_second_row_index, query_bytes_span));
+
+  // Ask server to respond for finalized query.
+  server.respond(query_bytes_span, response_bytes_span);
+
+  // Process response obtained from server, decoding database row.
+  EXPECT_TRUE(client.process_response(db_first_row_index, response_bytes_span, db_row_bytes_span));
+  // Retry processing response obtained from server, attempting to decode same database row.
+  EXPECT_FALSE(client.process_response(db_first_row_index, response_bytes_span, db_row_bytes_span));
+
+  // Process response obtained from server, decoding database row.
+  EXPECT_TRUE(client.process_response(db_second_row_index, response_bytes_span, db_row_bytes_span));
+  // Retry processing response obtained from server, attempting to decode same database row.
+  EXPECT_FALSE(client.process_response(db_second_row_index, response_bytes_span, db_row_bytes_span));
+
+  constexpr size_t db_second_row_bytes_begin_at = db_second_row_index * db_entry_byte_len;
+  EXPECT_TRUE(std::ranges::equal(db_row_bytes_span, db_bytes_span.subspan(db_second_row_bytes_begin_at, db_entry_byte_len)));
+}