cpp: start zkinterface_utils

cpp/CMakeLists.txt

@@ -14,7 +14,7 @@ enable_testing()
 
 
 # Frontend gadgetlib.
-add_executable(gadgetlib gadgetlib.cpp libsnark_integration.cpp gadgetlib_example.cpp)
+add_executable(gadgetlib gadgetlib.cpp zkinterface_utils.cpp libsnark_integration.cpp gadgetlib_example.cpp)
 # Dependencies.
 target_link_libraries(gadgetlib ff gmp)
 target_include_directories(gadgetlib PRIVATE . libsnark libsnark/depends/libff libsnark/depends/libfqfft /usr/local/include)
@@ -24,7 +24,7 @@ target_compile_definitions(gadgetlib PRIVATE -DBINARY_OUTPUT -DCURVE_ALT_BN128 -
 
 
 # Backend.
-add_executable(backend backend.cpp libsnark_integration.cpp)
+add_executable(backend backend.cpp zkinterface_utils.cpp libsnark_integration.cpp)
 add_test(backend backend)
 # Dependencies.
 target_link_libraries(backend ff gmp)

cpp/gadgetlib.cpp

@@ -18,7 +18,7 @@ bool write_to_file(void *context, unsigned char *message) {
     return true;
 }
 
-FlatBufferBuilder make_input_circuit() {
+void make_input_circuit(vector<uint8_t> &output) {
     FlatBufferBuilder builder;
 
     auto connections = CreateVariables(
@@ -32,34 +32,37 @@ FlatBufferBuilder make_input_circuit() {
 
     auto root = CreateRoot(builder, Message_Circuit, circuit.Union());
     builder.FinishSizePrefixed(root);
-    return builder;
+
+    // Append to the output buffer.
+    uint8_t *begin = builder.GetBufferPointer();
+    output.insert(output.end(), begin, begin + builder.GetSize());
 }
 
-FlatBufferBuilder make_command(string action) {
+void make_command(vector<uint8_t> &output, string action) {
     bool constraints_generation = (action == "constraints");
     bool witness_generation = (action == "witness");
 
     FlatBufferBuilder builder;
     auto command = CreateCommand(builder, constraints_generation, witness_generation);
     auto root = CreateRoot(builder, Message_Command, command.Union());
     builder.FinishSizePrefixed(root);
-    return builder;
+
+    // Append to the output buffer.
+    uint8_t *begin = builder.GetBufferPointer();
+    output.insert(output.end(), begin, begin + builder.GetSize());
 }
 
 void run(string action, string zkif_out_path) {
-
-    auto circuit_builder = make_input_circuit();
-    auto circuit_msg = circuit_builder.GetBufferPointer();
-
-    auto command_build = make_command(action);
-    auto command_msg = command_build.GetBufferPointer();
+    vector<uint8_t> buf;
+    make_input_circuit(buf);
+    make_command(buf, action);
 
     string constraints_name = "out_constraints.zkif";
     string witness_name = "out_witness.zkif";
     string return_name = "out_return.zkif";
 
     gadgetlib_example::call_gadget_example(
-            circuit_msg,
+            buf.data(),
             write_to_file, &constraints_name,
             write_to_file, &witness_name,
             write_to_file, &return_name);

cpp/libsnark_integration.cpp

@@ -7,37 +7,6 @@
 
 namespace zkinterface_libsnark {
 
-// ==== Reading helpers ====
-
-    uoffset_t read_size_prefix(void *buffer) {
-        uoffset_t message_length = *reinterpret_cast<uoffset_t *>(buffer);
-        return sizeof(uoffset_t) + message_length;
-    }
-
-    const Root *find_message(vector<char> &buffer, Message type) {
-        auto offset = 0;
-
-        while (offset + sizeof(uoffset_t) * 2 <= buffer.size()) {
-            auto current = buffer.data() + offset;
-
-            auto size = read_size_prefix(current);
-            if (offset + size > buffer.size()) {
-                throw "invalid offset";
-            }
-
-            auto root = GetSizePrefixedRoot(current);
-
-            if (root->message_type() == type) {
-                return root; // Found.
-            }
-
-            offset += size;
-        }
-
-        throw MessageNotFoundException();
-    }
-
-
 // ==== Element conversion helpers ====
 
     // Bytes to Bigint. Little-Endian.

cpp/libsnark_integration.hpp

@@ -6,12 +6,13 @@
 #ifndef ZKIF_LIBSNARK_INTEGRATION_H_
 #define ZKIF_LIBSNARK_INTEGRATION_H_
 
-#include "zkinterface.h"
-#include "zkinterface_generated.h"
-
 #include "libsnark/gadgetlib1/gadget.hpp"
 #include "libff/common/default_types/ec_pp.hpp"
 
+#include "zkinterface.h"
+#include "zkinterface_generated.h"
+#include "zkinterface_utils.hpp"
+
 using namespace zkinterface;
 using flatbuffers::FlatBufferBuilder;
 using flatbuffers::uoffset_t;
@@ -24,6 +25,7 @@ using libff::bigint;
 using libff::bit_vector;
 
 namespace zkinterface_libsnark {
+    using namespace zkinterface_utils;
 
     typedef libff::default_ec_pp CurveT;
     typedef libff::Fr<CurveT> FieldT;
@@ -46,20 +48,6 @@ namespace zkinterface_libsnark {
     };
 
 
-// ==== Reading helpers ====
-
-    uoffset_t read_size_prefix(void *buffer);
-
-    class MessageNotFoundException : public std::exception {
-    public:
-        inline const char *what() const throw() {
-            return "message of the required type not found";
-        }
-    };
-
-    const Root *find_message(vector<char> &buffer, Message type);
-
-
 // ==== Element conversion helpers ====
 
     // Bytes to Bigint. Little-Endian.

cpp/libsnark_zkif_import.cpp

@@ -22,7 +22,7 @@ namespace zkinterface_libsnark {
         import_zkif(protoboard<FieldT> &pb, const std::string &annotation_prefix) :
                 gadget<FieldT>(pb, annotation_prefix) {}
 
-        protoboard<FieldT>* get_pb() { return &pb; }
+        protoboard<FieldT> *get_pb() { return &pb; }
 
         void load(vector<char> &buf) {
             buffer = buf;
@@ -33,9 +33,9 @@ namespace zkinterface_libsnark {
             return root->message_as_Circuit();
         }
 
-        const R1CSConstraints *get_constraints() {
-            auto root = find_message(buffer, Message_R1CSConstraints);
-            return root->message_as_R1CSConstraints();
+        const ConstraintSystem *get_constraints() {
+            auto root = find_message(buffer, Message_ConstraintSystem);
+            return root->message_as_ConstraintSystem();
         }
 
         const Witness *get_witness() {

cpp/zkinterface_utils.cpp

@@ -0,0 +1,37 @@
+// zkInterface - integration helpers.
+//
+// @author Aurélien Nicolas <info@nau.re> for QED-it.com
+// @date 2020
+
+#include "zkinterface_utils.hpp"
+
+namespace zkinterface_utils {
+
+    uoffset_t read_size_prefix(void *buffer) {
+        uoffset_t message_length = *reinterpret_cast<uoffset_t *>(buffer);
+        return sizeof(uoffset_t) + message_length;
+    }
+
+    const Root *find_message(vector<char> &buffer, Message type) {
+        auto offset = 0;
+
+        while (offset + sizeof(uoffset_t) * 2 <= buffer.size()) {
+            auto current = buffer.data() + offset;
+
+            auto size = read_size_prefix(current);
+            if (offset + size > buffer.size()) {
+                throw "invalid offset";
+            }
+
+            auto root = GetSizePrefixedRoot(current);
+
+            if (root->message_type() == type) {
+                return root; // Found.
+            }
+
+            offset += size;
+        }
+
+        throw MessageNotFoundException();
+    }
+} // namespace zkinterface_utils

cpp/zkinterface_utils.hpp

@@ -0,0 +1,31 @@
+// zkInterface - integration helpers.
+//
+// @author Aurélien Nicolas <info@nau.re> for QED-it.com
+// @date 2020
+
+#ifndef ZKINTERFACE_ZKINTERFACE_UTILS_HPP
+#define ZKINTERFACE_ZKINTERFACE_UTILS_HPP
+
+#include "zkinterface_generated.h"
+
+namespace zkinterface_utils {
+    using namespace std;
+    using namespace flatbuffers;
+    using namespace zkinterface;
+
+
+// ==== Reading helpers ====
+
+    uoffset_t read_size_prefix(void *buffer);
+
+    const Root *find_message(vector<char> &buffer, Message type);
+
+    class MessageNotFoundException : public std::exception {
+    public:
+        inline const char *what() const throw() {
+            return "message of the required type not found";
+        }
+    };
+
+}
+#endif //ZKINTERFACE_ZKINTERFACE_UTILS_HPP