support r1cs created by circom2 (#122)

* support r1cs created by circom2

* upgrade version to 0.1.6

* fix

* Update package.json

Co-authored-by: HAOYUatHZ <37070449+HAOYUatHZ@users.noreply.github.com>

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "plonkit"
-version = "0.1.5"
+version = "0.1.6"
 authors = [ "Roman Semenov <semenov.roma@gmail.com>", "Zhuo Zhang <mycinbrin@gmail.com>", "Haoyu LIN <chris.haoyul@gmail.com>" ]
 description = "Library for working with circom circuits in plonk proof system"
 homepage = "https://github.com/fluidex/plonkit"

README.md

@@ -5,7 +5,9 @@
 A zkSNARK toolkit to work with [circom](https://github.com/iden3/circom) zkSNARKs DSL in [plonk](https://eprint.iacr.org/2019/953) proof system. Based on [zkutil](https://github.com/poma/zkutil) and [bellman_ce](https://github.com/matter-labs/bellman).
 
 ## Prerequisites
-+ https://github.com/fluidex/snarkit
+
+1. install [circom](https://docs.circom.io/getting-started/installation/) into $PATH
+2. install snarkit2 into $PATH: `npm install -g snarkit2`
 
 ## Features
 
@@ -75,7 +77,7 @@ circuit.circom  input.json  setup_2^20.key
 
 # generate witness for this circuit
 # another option here is use the snarkjs/circom cli like contrib/process_circom_circuit.sh
-> npx snarkit check . --witness_type bin --backend wasm
+> snarkit2 check . --witness_type bin --backend wasm
 
 
 # Generate a snark proof using the universal setup monomial-form SRS

package.json

@@ -1,6 +1,6 @@
 {
   "name": "plonkit",
-  "version": "0.1.5",
+  "version": "0.1.6",
   "description": "A zkSNARK toolkit to work with circom zkSNARKs DSL in plonk proof system",
   "main": "index.js",
   "scripts": {

src/bin/main.rs

@@ -18,7 +18,7 @@ use plonkit::recursive;
 
 /// A zkSNARK toolkit to work with circom zkSNARKs DSL in plonk proof system
 #[derive(Clap)]
-#[clap(version = "0.0.4")]
+#[clap(version = "0.1.6")]
 struct Opts {
     #[clap(subcommand)]
     command: SubCommand,

src/r1cs_file.rs

@@ -7,9 +7,13 @@ use crate::bellman_ce::pairing::{
 };
 use crate::circom_circuit::Constraint;
 use byteorder::{LittleEndian, ReadBytesExt};
-use std::io::{Error, ErrorKind, Read, Result};
+use std::{
+    collections::HashMap,
+    io::{Error, ErrorKind, Read, Result, Seek, SeekFrom},
+};
 
 // R1CSFile's header
+#[derive(Debug, Default)]
 pub struct Header {
     pub field_size: u32,
     pub prime_size: Vec<u8>,
@@ -22,6 +26,7 @@ pub struct Header {
 }
 
 // R1CSFile parse result
+#[derive(Debug, Default)]
 pub struct R1CSFile<E: Engine> {
     pub version: u32,
     pub header: Header,
@@ -92,7 +97,7 @@ fn read_map<R: Read>(mut reader: R, size: u64, header: &Header) -> Result<Vec<u6
     Ok(vec)
 }
 
-pub fn from_reader<R: Read>(mut reader: R) -> Result<R1CSFile<Bn256>> {
+pub fn from_reader<R: Read + Seek>(mut reader: R) -> Result<R1CSFile<Bn256>> {
     let mut magic = [0u8; 4];
     reader.read_exact(&mut magic)?;
     if magic != [0x72, 0x31, 0x63, 0x73] {
@@ -107,24 +112,38 @@ pub fn from_reader<R: Read>(mut reader: R) -> Result<R1CSFile<Bn256>> {
 
     let num_sections = reader.read_u32::<LittleEndian>()?;
 
-    // todo: rewrite this to support different section order and unknown sections
-    // todo: handle sec_size correctly
-    let sec_type = reader.read_u32::<LittleEndian>()?;
-    let sec_size = reader.read_u64::<LittleEndian>()?;
-    let header = read_header(&mut reader, sec_size)?;
+    // section type -> file offset
+    let mut section_offsets = HashMap::<u32, u64>::new();
+    let mut section_sizes = HashMap::<u32, u64>::new();
+
+    // get file offset of each section
+    for _ in 0..num_sections {
+        let section_type = reader.read_u32::<LittleEndian>()?;
+        let section_size = reader.read_u64::<LittleEndian>()?;
+        let offset = reader.seek(SeekFrom::Current(0))?;
+        section_offsets.insert(section_type, offset);
+        section_sizes.insert(section_type, section_size);
+        reader.seek(SeekFrom::Current(section_size as i64))?;
+    }
+
+    let header_type = 1;
+    let constraint_type = 2;
+    let wire2label_type = 3;
+
+    reader.seek(SeekFrom::Start(*section_offsets.get(&header_type).unwrap()))?;
+    let header = read_header(&mut reader, *section_sizes.get(&header_type).unwrap())?;
     if header.field_size != 32 {
         return Err(Error::new(ErrorKind::InvalidData, "This parser only supports 32-byte fields"));
     }
     if header.prime_size != hex!("010000f093f5e1439170b97948e833285d588181b64550b829a031e1724e6430") {
         return Err(Error::new(ErrorKind::InvalidData, "This parser only supports bn256"));
     }
-    let sec_type = reader.read_u32::<LittleEndian>()?;
-    let sec_size = reader.read_u64::<LittleEndian>()?;
-    let constraints = read_constraints::<&mut R, Bn256>(&mut reader, sec_size, &header)?;
 
-    let sec_type = reader.read_u32::<LittleEndian>()?;
-    let sec_size = reader.read_u64::<LittleEndian>()?;
-    let wire_mapping = read_map(&mut reader, sec_size, &header)?;
+    reader.seek(SeekFrom::Start(*section_offsets.get(&constraint_type).unwrap()))?;
+    let constraints = read_constraints::<&mut R, Bn256>(&mut reader, *section_sizes.get(&constraint_type).unwrap(), &header)?;
+
+    reader.seek(SeekFrom::Start(*section_offsets.get(&wire2label_type).unwrap()))?;
+    let wire_mapping = read_map(&mut reader, *section_sizes.get(&wire2label_type).unwrap(), &header)?;
 
     Ok(R1CSFile {
         version,
@@ -136,6 +155,8 @@ pub fn from_reader<R: Read>(mut reader: R) -> Result<R1CSFile<Bn256>> {
 
 #[cfg(test)]
 mod tests {
+    use std::io::{BufReader, Cursor};
+
     use super::*;
 
     #[test]
@@ -193,7 +214,8 @@ mod tests {
         );
 
         use crate::bellman_ce::pairing::ff;
-        let file = from_reader(&data[..]).unwrap();
+        let reader = BufReader::new(Cursor::new(&data[..]));
+        let file = from_reader(reader).unwrap();
         assert_eq!(file.version, 1);
 
         assert_eq!(file.header.field_size, 32);

src/reader.rs

@@ -3,7 +3,7 @@ use byteorder::{LittleEndian, ReadBytesExt};
 use itertools::Itertools;
 use std::collections::BTreeMap;
 use std::fs::{File, OpenOptions};
-use std::io::{BufRead, BufReader, Read};
+use std::io::{BufRead, BufReader, Read, Seek};
 use std::str;
 
 use crate::bellman_ce::{
@@ -224,7 +224,7 @@ fn load_r1cs_from_bin_file(filename: &str) -> (R1CS<Bn256>, Vec<usize>) {
 }
 
 /// load r1cs from bin by a reader
-fn load_r1cs_from_bin<R: Read>(reader: R) -> (R1CS<Bn256>, Vec<usize>) {
+fn load_r1cs_from_bin<R: Read + Seek>(reader: R) -> (R1CS<Bn256>, Vec<usize>) {
     let file = crate::r1cs_file::from_reader(reader).expect("unable to read.");
     let num_inputs = (1 + file.header.n_pub_in + file.header.n_pub_out) as usize;
     let num_variables = file.header.n_wires as usize;