circom-compat/src/circom/r1cs_reader.rs
src/circom/r1cs_reader.rsRaw
1//! R1CS circom file reader
2//! Copied from https://github.com/poma/zkutil
3use byteorder::{LittleEndian, ReadBytesExt};
4use std::io::{Error, ErrorKind, Result};
5
6use ark_ec::PairingEngine;
7use ark_ff::FromBytes;
8use ark_std::io::Read;
9
10use super::{ConstraintVec, Constraints};
11
12#[derive(Clone, Debug)]
13pub struct R1CS<E: PairingEngine> {
14 pub num_inputs: usize,
15 pub num_aux: usize,
16 pub num_variables: usize,
17 pub constraints: Vec<Constraints<E>>,
18 pub wire_mapping: Option<Vec<usize>>,
19}
20
21impl<E: PairingEngine> From<R1CSFile<E>> for R1CS<E> {
22 fn from(file: R1CSFile<E>) -> Self {
23 let num_inputs = (1 + file.header.n_pub_in + file.header.n_pub_out) as usize;
24 let num_variables = file.header.n_wires as usize;
25 let num_aux = num_variables - num_inputs;
26 R1CS {
27 num_aux,
28 num_inputs,
29 num_variables,
30 constraints: file.constraints,
31 wire_mapping: Some(file.wire_mapping.iter().map(|e| *e as usize).collect()),
32 }
33 }
34}
35
36pub struct R1CSFile<E: PairingEngine> {
37 pub version: u32,
38 pub header: Header,
39 pub constraints: Vec<Constraints<E>>,
40 pub wire_mapping: Vec<u64>,
41}
42
43impl<E: PairingEngine> R1CSFile<E> {
44 pub fn new<R: Read>(mut reader: R) -> Result<R1CSFile<E>> {
45 let mut magic = [0u8; 4];
46 reader.read_exact(&mut magic)?;
47 if magic != [0x72, 0x31, 0x63, 0x73] {
48 // magic = "r1cs"
49 return Err(Error::new(ErrorKind::InvalidData, "Invalid magic number"));
50 }
51
52 let version = reader.read_u32::<LittleEndian>()?;
53 if version != 1 {
54 return Err(Error::new(ErrorKind::InvalidData, "Unsupported version"));
55 }
56
57 let _num_sections = reader.read_u32::<LittleEndian>()?;
58
59 // todo: rewrite this to support different section order and unknown sections
60 // todo: handle sec_size correctly
61 let _sec_type = reader.read_u32::<LittleEndian>()?;
62 let sec_size = reader.read_u64::<LittleEndian>()?;
63
64 let header = Header::new(&mut reader, sec_size)?;
65 let _sec_type = reader.read_u32::<LittleEndian>()?;
66 let _sec_size = reader.read_u64::<LittleEndian>()?;
67 let constraints = read_constraints::<&mut R, E>(&mut reader, &header)?;
68
69 let _sec_type = reader.read_u32::<LittleEndian>()?;
70 let sec_size = reader.read_u64::<LittleEndian>()?;
71 let wire_mapping = read_map(&mut reader, sec_size, &header)?;
72
73 Ok(R1CSFile {
74 version,
75 header,
76 constraints,
77 wire_mapping,
78 })
79 }
80}
81
82pub struct Header {
83 pub field_size: u32,
84 pub prime_size: Vec<u8>,
85 pub n_wires: u32,
86 pub n_pub_out: u32,
87 pub n_pub_in: u32,
88 pub n_prv_in: u32,
89 pub n_labels: u64,
90 pub n_constraints: u32,
91}
92
93impl Header {
94 fn new<R: Read>(mut reader: R, size: u64) -> Result<Header> {
95 let field_size = reader.read_u32::<LittleEndian>()?;
96 if field_size != 32 {
97 return Err(Error::new(
98 ErrorKind::InvalidData,
99 "This parser only supports 32-byte fields",
100 ));
101 }
102
103 if size != 32 + field_size as u64 {
104 return Err(Error::new(
105 ErrorKind::InvalidData,
106 "Invalid header section size",
107 ));
108 }
109
110 let mut prime_size = vec![0u8; field_size as usize];
111 reader.read_exact(&mut prime_size)?;
112
113 if prime_size
114 != hex::decode("010000f093f5e1439170b97948e833285d588181b64550b829a031e1724e6430")
115 .unwrap()
116 {
117 return Err(Error::new(
118 ErrorKind::InvalidData,
119 "This parser only supports bn256",
120 ));
121 }
122
123 Ok(Header {
124 field_size,
125 prime_size,
126 n_wires: reader.read_u32::<LittleEndian>()?,
127 n_pub_out: reader.read_u32::<LittleEndian>()?,
128 n_pub_in: reader.read_u32::<LittleEndian>()?,
129 n_prv_in: reader.read_u32::<LittleEndian>()?,
130 n_labels: reader.read_u64::<LittleEndian>()?,
131 n_constraints: reader.read_u32::<LittleEndian>()?,
132 })
133 }
134}
135
136fn read_constraint_vec<R: Read, E: PairingEngine>(mut reader: R) -> Result<ConstraintVec<E>> {
137 let n_vec = reader.read_u32::<LittleEndian>()? as usize;
138 let mut vec = Vec::with_capacity(n_vec);
139 for _ in 0..n_vec {
140 vec.push((
141 reader.read_u32::<LittleEndian>()? as usize,
142 E::Fr::read(&mut reader)?,
143 ));
144 }
145 Ok(vec)
146}
147
148fn read_constraints<R: Read, E: PairingEngine>(
149 mut reader: R,
150 header: &Header,
151) -> Result<Vec<Constraints<E>>> {
152 // todo check section size
153 let mut vec = Vec::with_capacity(header.n_constraints as usize);
154 for _ in 0..header.n_constraints {
155 vec.push((
156 read_constraint_vec::<&mut R, E>(&mut reader)?,
157 read_constraint_vec::<&mut R, E>(&mut reader)?,
158 read_constraint_vec::<&mut R, E>(&mut reader)?,
159 ));
160 }
161 Ok(vec)
162}
163
164fn read_map<R: Read>(mut reader: R, size: u64, header: &Header) -> Result<Vec<u64>> {
165 if size != header.n_wires as u64 * 8 {
166 return Err(Error::new(
167 ErrorKind::InvalidData,
168 "Invalid map section size",
169 ));
170 }
171 let mut vec = Vec::with_capacity(header.n_wires as usize);
172 for _ in 0..header.n_wires {
173 vec.push(reader.read_u64::<LittleEndian>()?);
174 }
175 if vec[0] != 0 {
176 return Err(Error::new(
177 ErrorKind::InvalidData,
178 "Wire 0 should always be mapped to 0",
179 ));
180 }
181 Ok(vec)
182}
183
184#[cfg(test)]
185mod tests {
186 use super::*;
187 use ark_bn254::{Bn254, Fr};
188
189 #[test]
190 fn sample() {
191 let data = hex_literal::hex!(
192 "
193 72316373
194 01000000
195 03000000
196 01000000 40000000 00000000
197 20000000
198 010000f0 93f5e143 9170b979 48e83328 5d588181 b64550b8 29a031e1 724e6430
199 07000000
200 01000000
201 02000000
202 03000000
203 e8030000 00000000
204 03000000
205 02000000 88020000 00000000
206 02000000
207 05000000 03000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
208 06000000 08000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
209 03000000
210 00000000 02000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
211 02000000 14000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
212 03000000 0C000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
213 02000000
214 00000000 05000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
215 02000000 07000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
216 03000000
217 01000000 04000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
218 04000000 08000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
219 05000000 03000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
220 02000000
221 03000000 2C000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
222 06000000 06000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
223 00000000
224 01000000
225 06000000 04000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
226 03000000
227 00000000 06000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
228 02000000 0B000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
229 03000000 05000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
230 01000000
231 06000000 58020000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
232 03000000 38000000 00000000
233 00000000 00000000
234 03000000 00000000
235 0a000000 00000000
236 0b000000 00000000
237 0c000000 00000000
238 0f000000 00000000
239 44010000 00000000
240 "
241 );
242
243 let file = R1CSFile::<Bn254>::new(&data[..]).unwrap();
244 assert_eq!(file.version, 1);
245
246 assert_eq!(file.header.field_size, 32);
247 assert_eq!(
248 file.header.prime_size,
249 hex::decode("010000f093f5e1439170b97948e833285d588181b64550b829a031e1724e6430")
250 .unwrap(),
251 );
252 assert_eq!(file.header.n_wires, 7);
253 assert_eq!(file.header.n_pub_out, 1);
254 assert_eq!(file.header.n_pub_in, 2);
255 assert_eq!(file.header.n_prv_in, 3);
256 assert_eq!(file.header.n_labels, 0x03e8);
257 assert_eq!(file.header.n_constraints, 3);
258
259 assert_eq!(file.constraints.len(), 3);
260 assert_eq!(file.constraints[0].0.len(), 2);
261 assert_eq!(file.constraints[0].0[0].0, 5);
262 assert_eq!(file.constraints[0].0[0].1, Fr::from(3));
263 assert_eq!(file.constraints[2].1[0].0, 0);
264 assert_eq!(file.constraints[2].1[0].1, Fr::from(6));
265 assert_eq!(file.constraints[1].2.len(), 0);
266
267 assert_eq!(file.wire_mapping.len(), 7);
268 assert_eq!(file.wire_mapping[1], 3);
269 }
270}