zkey: expose only 1 method - everything else private

src/zkey.rs

@@ -1,4 +1,4 @@
-//! ZKey
+//! ZKey Parsing
 //!
 //! Each ZKey file is broken into sections:
 //!  Header(1)
@@ -32,30 +32,35 @@ use byteorder::{LittleEndian, ReadBytesExt};
 
 use std::{
     collections::HashMap,
-    io::{Cursor, Read, Result as IoResult},
+    io::{Read, Result as IoResult, Seek, SeekFrom},
 };
 
 use ark_bn254::{Bn254, Fq, Fq2, G1Affine, G2Affine};
 use ark_groth16::{ProvingKey, VerifyingKey};
-use ark_serialize::CanonicalSerialize;
 use num_traits::Zero;
 
 #[derive(Clone, Debug)]
-pub struct Section {
+struct Section {
     position: u64,
     size: usize,
 }
 
+/// Reads a SnarkJS ZKey file into an Arkworks ProvingKey.
+pub fn read_zkey<R: Read + Seek>(reader: &mut R) -> IoResult<ProvingKey<Bn254>> {
+    let mut binfile = BinFile::new(reader)?;
+    binfile.proving_key()
+}
+
 #[derive(Debug)]
-pub struct BinFile<'a> {
+struct BinFile<'a, R> {
     ftype: String,
     version: u32,
     sections: HashMap<u32, Vec<Section>>,
-    reader: &'a mut Cursor<&'a [u8]>,
+    reader: &'a mut R,
 }
 
-impl<'a> BinFile<'a> {
-    pub fn new(reader: &'a mut Cursor<&'a [u8]>) -> IoResult<Self> {
+impl<'a, R: Read + Seek> BinFile<'a, R> {
+    fn new(reader: &'a mut R) -> IoResult<Self> {
         let mut magic = [0u8; 4];
         reader.read_exact(&mut magic)?;
 
@@ -70,11 +75,11 @@ impl<'a> BinFile<'a> {
 
             let section = sections.entry(section_id).or_insert_with(Vec::new);
             section.push(Section {
-                position: reader.position(),
+                position: reader.stream_position()?,
                 size: section_length as usize,
             });
 
-            reader.set_position(reader.position() + section_length);
+            reader.seek(SeekFrom::Current(section_length as i64))?;
         }
 
         Ok(Self {
@@ -85,7 +90,7 @@ impl<'a> BinFile<'a> {
         })
     }
 
-    pub fn proving_key(&mut self) -> IoResult<ProvingKey<Bn254>> {
+    fn proving_key(&mut self) -> IoResult<ProvingKey<Bn254>> {
         let header = self.groth_header()?;
         let ic = self.ic(header.n_public)?;
 
@@ -121,64 +126,60 @@ impl<'a> BinFile<'a> {
         self.sections.get(&id).unwrap()[0].clone()
     }
 
-    pub fn groth_header(&mut self) -> IoResult<HeaderGroth> {
+    fn groth_header(&mut self) -> IoResult<HeaderGroth> {
         let section = self.get_section(2);
         let header = HeaderGroth::new(&mut self.reader, &section)?;
         Ok(header)
     }
 
-    pub fn ic(&mut self, n_public: usize) -> IoResult<Vec<G1Affine>> {
+    fn ic(&mut self, n_public: usize) -> IoResult<Vec<G1Affine>> {
         // the range is non-inclusive so we do +1 to get all inputs
         self.g1_section(n_public + 1, 3)
     }
 
     // Section 4 is the coefficients, we ignore it
 
-    pub fn a_query(&mut self, n_vars: usize) -> IoResult<Vec<G1Affine>> {
+    fn a_query(&mut self, n_vars: usize) -> IoResult<Vec<G1Affine>> {
         self.g1_section(n_vars, 5)
     }
 
-    pub fn b_g1_query(&mut self, n_vars: usize) -> IoResult<Vec<G1Affine>> {
+    fn b_g1_query(&mut self, n_vars: usize) -> IoResult<Vec<G1Affine>> {
         self.g1_section(n_vars, 6)
     }
 
-    pub fn b_g2_query(&mut self, n_vars: usize) -> IoResult<Vec<G2Affine>> {
+    fn b_g2_query(&mut self, n_vars: usize) -> IoResult<Vec<G2Affine>> {
         self.g2_section(n_vars, 7)
     }
 
-    pub fn l_query(&mut self, n_vars: usize) -> IoResult<Vec<G1Affine>> {
+    fn l_query(&mut self, n_vars: usize) -> IoResult<Vec<G1Affine>> {
         self.g1_section(n_vars, 8)
     }
 
-    pub fn h_query(&mut self, n_vars: usize) -> IoResult<Vec<G1Affine>> {
+    fn h_query(&mut self, n_vars: usize) -> IoResult<Vec<G1Affine>> {
         self.g1_section(n_vars, 9)
     }
 
     fn g1_section(&mut self, num: usize, section_id: usize) -> IoResult<Vec<G1Affine>> {
         let section = self.get_section(section_id as u32);
-        deserialize_g1_vec(
-            &self.reader.get_ref()[section.position as usize..],
-            num as u32,
-        )
+        self.reader.seek(SeekFrom::Start(section.position))?;
+        deserialize_g1_vec(self.reader, num as u32)
     }
 
     fn g2_section(&mut self, num: usize, section_id: usize) -> IoResult<Vec<G2Affine>> {
         let section = self.get_section(section_id as u32);
-        deserialize_g2_vec(
-            &self.reader.get_ref()[section.position as usize..],
-            num as u32,
-        )
+        self.reader.seek(SeekFrom::Start(section.position))?;
+        deserialize_g2_vec(self.reader, num as u32)
     }
 }
 
 #[derive(Default, Clone, Debug, CanonicalDeserialize)]
 pub struct ZVerifyingKey {
-    pub alpha_g1: G1Affine,
-    pub beta_g1: G1Affine,
-    pub beta_g2: G2Affine,
-    pub gamma_g2: G2Affine,
-    pub delta_g1: G1Affine,
-    pub delta_g2: G2Affine,
+    alpha_g1: G1Affine,
+    beta_g1: G1Affine,
+    beta_g2: G2Affine,
+    gamma_g2: G2Affine,
+    delta_g1: G1Affine,
+    delta_g2: G2Affine,
 }
 
 impl ZVerifyingKey {
@@ -202,25 +203,25 @@ impl ZVerifyingKey {
 }
 
 #[derive(Clone, Debug)]
-pub struct HeaderGroth {
-    pub n8q: u32,
-    pub q: BigInteger256,
+struct HeaderGroth {
+    n8q: u32,
+    q: BigInteger256,
 
-    pub n8r: u32,
-    pub r: BigInteger256,
+    n8r: u32,
+    r: BigInteger256,
 
-    pub n_vars: usize,
-    pub n_public: usize,
+    n_vars: usize,
+    n_public: usize,
 
-    pub domain_size: u32,
-    pub power: u32,
+    domain_size: u32,
+    power: u32,
 
-    pub verifying_key: ZVerifyingKey,
+    verifying_key: ZVerifyingKey,
 }
 
 impl HeaderGroth {
-    pub fn new(reader: &mut Cursor<&[u8]>, section: &Section) -> IoResult<Self> {
-        reader.set_position(section.position);
+    fn new<R: Read + Seek>(reader: &mut R, section: &Section) -> IoResult<Self> {
+        reader.seek(SeekFrom::Start(section.position))?;
         Self::read(reader)
     }
 
@@ -282,31 +283,18 @@ fn deserialize_g2(reader: &mut R) -> IoResult {
     Ok(G2Affine::new(f1, f2, infinity))
 }
 
-fn deserialize_g1_vec(buf: &[u8], n_vars: u32) -> IoResult<Vec<G1Affine>> {
-    let size = G1Affine::zero().uncompressed_size();
-    let mut v = vec![];
-    for i in 0..n_vars as usize {
-        let el = deserialize_g1(&mut &buf[i * size..(i + 1) * size])?;
-        v.push(el);
-    }
-    Ok(v)
+fn deserialize_g1_vec<R: Read>(reader: &mut R, n_vars: u32) -> IoResult<Vec<G1Affine>> {
+    (0..n_vars).map(|_| deserialize_g1(reader)).collect()
 }
 
-fn deserialize_g2_vec(buf: &[u8], n_vars: u32) -> IoResult<Vec<G2Affine>> {
-    let size = G2Affine::zero().uncompressed_size();
-    let mut v = vec![];
-    for i in 0..n_vars as usize {
-        let el = deserialize_g2(&mut &buf[i * size..(i + 1) * size])?;
-        v.push(el);
-    }
-    Ok(v)
+fn deserialize_g2_vec<R: Read>(reader: &mut R, n_vars: u32) -> IoResult<Vec<G2Affine>> {
+    (0..n_vars).map(|_| deserialize_g2(reader)).collect()
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
     use ark_bn254::{G1Projective, G2Projective};
-    use memmap::*;
     use num_bigint::BigUint;
     use serde_json::Value;
     use std::fs::File;
@@ -420,7 +408,7 @@ mod tests {
             .collect::<Vec<_>>();
         let expected = vec![g1_one(); n_vars];
 
-        let de = deserialize_g1_vec(&buf[..], n_vars as u32).unwrap();
+        let de = deserialize_g1_vec(&mut &buf[..], n_vars as u32).unwrap();
         assert_eq!(expected, de);
     }
 
@@ -444,7 +432,7 @@ mod tests {
             .collect::<Vec<_>>();
         let expected = vec![g2_one(); n_vars];
 
-        let de = deserialize_g2_vec(&buf[..], n_vars as u32).unwrap();
+        let de = deserialize_g2_vec(&mut &buf[..], n_vars as u32).unwrap();
         assert_eq!(expected, de);
     }
 
@@ -465,14 +453,8 @@ mod tests {
         // Then:
         // `snarkjs zkey new circuit.r1cs powersOfTau28_hez_final_10.ptau test.zkey`
         let path = "./test-vectors/test.zkey";
-        let file = File::open(path).unwrap();
-        let map = unsafe {
-            MmapOptions::new()
-                .map(&file)
-                .expect("unable to create a memory map")
-        };
-        let mut reader = Cursor::new(map.as_ref());
-        let mut binfile = BinFile::new(&mut reader).unwrap();
+        let mut file = File::open(path).unwrap();
+        let mut binfile = BinFile::new(&mut file).unwrap();
         let header = binfile.groth_header().unwrap();
         assert_eq!(header.n_vars, 4);
         assert_eq!(header.n_public, 1);
@@ -483,15 +465,8 @@ mod tests {
     #[test]
     fn deser_key() {
         let path = "./test-vectors/test.zkey";
-        let file = File::open(path).unwrap();
-        let map = unsafe {
-            MmapOptions::new()
-                .map(&file)
-                .expect("unable to create a memory map")
-        };
-        let mut reader = Cursor::new(map.as_ref());
-        let mut binfile = BinFile::new(&mut reader).unwrap();
-        let params = binfile.proving_key().unwrap();
+        let mut file = File::open(path).unwrap();
+        let params = read_zkey(&mut file).unwrap();
 
         // Check IC
         let expected = vec![
@@ -710,16 +685,8 @@ mod tests {
     #[test]
     fn deser_vk() {
         let path = "./test-vectors/test.zkey";
-        let file = File::open(path).unwrap();
-        let map = unsafe {
-            MmapOptions::new()
-                .map(&file)
-                .expect("unable to create a memory map")
-        };
-        let mut reader = Cursor::new(map.as_ref());
-        let mut binfile = BinFile::new(&mut reader).unwrap();
-
-        let params = binfile.proving_key().unwrap();
+        let mut file = File::open(path).unwrap();
+        let params = read_zkey(&mut file).unwrap();
 
         let json = std::fs::read_to_string("./test-vectors/verification_key.json").unwrap();
         let json: Value = serde_json::from_str(&json).unwrap();
@@ -799,16 +766,8 @@ mod tests {
     #[test]
     fn verify_proof_with_zkey() {
         let path = "./test-vectors/test.zkey";
-        let file = File::open(path).unwrap();
-        let map = unsafe {
-            MmapOptions::new()
-                .map(&file)
-                .expect("unable to create a memory map")
-        };
-        let mut reader = Cursor::new(map.as_ref());
-        let mut binfile = BinFile::new(&mut reader).unwrap();
-
-        let params = binfile.proving_key().unwrap();
+        let mut file = File::open(path).unwrap();
+        let params = read_zkey(&mut file).unwrap(); // binfile.proving_key().unwrap();
 
         let cfg = CircuitConfig::<Bn254>::new(
             "./test-vectors/mycircuit.wasm",