Merge pull request #16 from QED-it/libsnark-e2e

libsnark-e2e: End-to-end Rust/C++ gadget and proving flow

.gitignore

@@ -1,5 +1,6 @@
 target/
 build/
+dist/
 libsnark
 *.a
 local/

Changelog.md

@@ -1,3 +1,29 @@
+# Version v1.1.3, 2020-07, Rust/C++/libSNARK end-to-end integration
+
+Rust:
+- *(breaking)* Expanded `*Owned` structures (`KeyValueOwned`, rename `write_into`, serialization of `ConstraintSystemOwned`).
+- *(breaking)* Generic code improvements (Rust 2018, common `Result`, naming, modules re-exports).
+- Consolidated all tools into one CLI called `zkif`.
+- Available commands:
+    - JSON converters (`json` and `pretty`).
+    - Human-readable decoder called `explain`.
+    - Example circuit generator.
+    - Statistics for cost estimation (`stats`).
+    - Support for byte streams to pipe with other CLIs (`cat` command and special `-` filename meaning stdin/stdout).
+- Established a convention for easy file-based usage. The tools accept a workspace directory where `.zkif` files are organized.
+- Structures to construct ZK statements. See `statement.rs / StatementBuilder`.
+- A trait `GadgetCallbacks` and basic implementations to interact with gadgets (e.g. libSNARK below).
+- Fixed a bug on empty variables array.
+
+libsnark-rust:
+- Support zero-copy mode using the generic `GadgetCallbacks` trait.
+- Tests with a TinyRAM gadget and `StatementBuilder`.
+
+C++:
+- Support for multiple messages of each type.
+- Simplify the `zkif_snark` CLI and work well with the workspace and pipe modes of the `zkif` CLI.
+
+
 # Version v1.1.2, 2020-06, libsnark and gadgetlib for Rust
 
 Rust:

README.md

@@ -81,16 +81,10 @@ In the `rust` directory, run unit tests:
 The following commands will generate and print a file containing the messages Circuit, R1CSConstraints, and Witness for a toy circuit in `rust/src/examples.rs`:
 
 ```
-cargo run --bin example > example.zkif
-cargo run --bin print   < example.zkif
+cargo run example  > example.zkif
+cargo run explain  < example.zkif
 ```
 
-This command will generate and compile Rust and C++ code, and run a test of both sides communicating through the standard interface:
-
-`cargo test --features cpp`
-
-<!-- TODO: Clarify what this tests -->
-
 ### Generated code
 
 Generated C++ and Rust code is included.

cpp/e2e_demo.sh

@@ -0,0 +1,30 @@
+#!/bin/sh
+set -ex
+
+# Build.
+cmake -DCMAKE_INSTALL_PREFIX=dist . && make install
+
+# Find the tools.
+alias zkif="cargo run --manifest-path ../rust/Cargo.toml"
+alias zkif_snark="dist/bin/zkif_snark"
+
+# Generate a test statement.
+pushd libsnark-rust
+ZKINTERFACE_LIBSNARK_PATH=../dist cargo test
+popd
+
+# Look at the files.
+DIR=libsnark-rust/local/test_statement
+MAIN=$DIR/main.zkif
+CONS=$DIR/constraints.zkif
+WITN=$DIR/witness.zkif
+NAME=$DIR/snark
+
+zkif explain $MAIN $CONS $WITN
+
+# Prove and verify.
+cat $MAIN $CONS $WITN | zkif_snark validate $NAME
+cat $MAIN $CONS       | zkif_snark setup    $NAME
+cat $MAIN $WITN       | zkif_snark prove    $NAME
+cat $MAIN             | zkif_snark verify   $NAME
+

cpp/gadget_cli.cpp

@@ -68,14 +68,14 @@ void run(string action, string zkif_out_prefix) {
   vector<char> command_msg;
   make_command(command_msg, action);
 
-  string constraints_name = zkif_out_prefix + "_constraints.zkif";
-  string witness_name = zkif_out_prefix + "_witness.zkif";
-  string return_name = zkif_out_prefix + "_return.zkif";
+  string constraints_name = zkif_out_prefix + "constraints.zkif";
+  string witness_name = zkif_out_prefix + "witness.zkif";
+  string response_name = zkif_out_prefix + "response.zkif";
 
   gadgetlib_call_gadget(circuit_msg.data(), command_msg.data(),
                         callback_write_to_file, &constraints_name,
                         callback_write_to_file, &witness_name,
-                        callback_write_to_file, &return_name);
+                        callback_write_to_file, &response_name);
 }
 
 static const char USAGE[] =
@@ -88,13 +88,15 @@ static const char USAGE[] =
 
 int main(int argc, const char **argv) {
 
-  if (argc < 3) {
+  if (argc < 2) {
     cerr << USAGE << endl;
     return 1;
   }
 
+  string out_prefix = (argc > 2) ? string(argv[2]) : "";
+
   try {
-    run(string(argv[1]), string(argv[2]));
+    run(string(argv[1]), out_prefix);
     return 0;
   } catch (const char *msg) {
     cerr << msg << endl;

cpp/gadgetlib_alu.cpp

@@ -118,23 +118,27 @@ namespace gadgetlib_alu {
 
         // Gadget output.
         {
+            FlatBufferBuilder builder;
             VarIdConverter converter(circuit);
 
             vector<uint64_t> output_ids({
                 converter.get_variable_id(destval),
                 converter.get_variable_id(flag),
             });
-            auto output_values = elements_into_le({
-                pb.val(destval),
-                pb.val(flag),
-            });
 
-            FlatBufferBuilder builder;
+            Offset<Vector<unsigned char>> output_values;
+            if (command->witness_generation()) {
+                output_values = builder.CreateVector(
+                    elements_into_le({
+                            pb.val(destval),
+                            pb.val(flag),
+                        }));
+            }
 
             auto connections = CreateVariables(
                     builder,
                     builder.CreateVector(output_ids),
-                    builder.CreateVector(output_values));
+                    output_values);
 
             auto response = CreateCircuit(
                     builder,

cpp/libsnark-rust/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "zkinterface-libsnark"
-version = "1.1.2"
+version = "1.1.3"
 description = "Wrapper for libsnark / gadgetlib through zkInterface"
 homepage = "https://github.com/QED-it/zkinterface"
 repository = "https://github.com/QED-it/zkinterface/tree/master/cpp/libsnark-rust"
@@ -11,7 +11,7 @@ build = "build.rs"
 links = "zkif_gadgetlib"
 
 [dependencies]
-zkinterface = "1.1.2"
+zkinterface = "1.1.3"
 #zkinterface = { path = "../../rust" }
 
 [build-dependencies]