testudo/src/constraints.rs
src/constraints.rsRaw
1use std::{borrow::Borrow, vec};
2
3use super::scalar::Scalar;
4use crate::{
5 group::Fq,
6 math::Math,
7 sparse_mlpoly::{SparsePolyEntry, SparsePolynomial},
8 unipoly::UniPoly,
9};
10use ark_bls12_377::{constraints::PairingVar as IV, Bls12_377 as I, Fr};
11use ark_crypto_primitives::{
12 snark::BooleanInputVar, CircuitSpecificSetupSNARK, SNARKGadget, SNARK,
13};
14
15use ark_ff::{BitIteratorLE, PrimeField, Zero};
16use ark_groth16::{
17 constraints::{Groth16VerifierGadget, PreparedVerifyingKeyVar, ProofVar},
18 Groth16, PreparedVerifyingKey, Proof as GrothProof,
19};
20
21use ark_poly_commit::multilinear_pc::{
22 data_structures::{Commitment, Proof, VerifierKey},
23 MultilinearPC,
24};
25use ark_r1cs_std::{
26 alloc::{AllocVar, AllocationMode},
27 fields::fp::FpVar,
28 prelude::{Boolean, EqGadget, FieldVar},
29 R1CSVar,
30};
31use ark_relations::r1cs::{ConstraintSynthesizer, ConstraintSystemRef, Namespace, SynthesisError};
32use ark_sponge::{
33 constraints::CryptographicSpongeVar,
34 poseidon::{constraints::PoseidonSpongeVar, PoseidonParameters},
35};
36use rand::{CryptoRng, Rng};
37
38pub struct PoseidonTranscripVar {
39 pub cs: ConstraintSystemRef<Fr>,
40 pub sponge: PoseidonSpongeVar<Fr>,
41 pub params: PoseidonParameters<Fr>,
42}
43
44impl PoseidonTranscripVar {
45 fn new(
46 cs: ConstraintSystemRef<Fr>,
47 params: &PoseidonParameters<Fr>,
48 challenge: Option<Fr>,
49 ) -> Self {
50 let mut sponge = PoseidonSpongeVar::new(cs.clone(), params);
51
52 if let Some(c) = challenge {
53 let c_var = FpVar::<Fr>::new_witness(cs.clone(), || Ok(c)).unwrap();
54 sponge.absorb(&c_var).unwrap();
55 }
56
57 Self {
58 cs,
59 sponge,
60 params: params.clone(),
61 }
62 }
63
64 fn append(&mut self, input: &FpVar<Fr>) -> Result<(), SynthesisError> {
65 self.sponge.absorb(&input)
66 }
67
68 fn append_vector(&mut self, input_vec: &[FpVar<Fr>]) -> Result<(), SynthesisError> {
69 for input in input_vec.iter() {
70 self.append(input)?;
71 }
72 Ok(())
73 }
74
75 fn challenge(&mut self) -> Result<FpVar<Fr>, SynthesisError> {
76 let c_var = self.sponge.squeeze_field_elements(1).unwrap().remove(0);
77
78 Ok(c_var)
79 }
80
81 fn challenge_vector(&mut self, len: usize) -> Result<Vec<FpVar<Fr>>, SynthesisError> {
82 let c_vars = self.sponge.squeeze_field_elements(len).unwrap();
83
84 Ok(c_vars)
85 }
86}
87
88#[derive(Clone)]
89pub struct UniPolyVar {
90 pub coeffs: Vec<FpVar<Fr>>,
91}
92
93impl AllocVar<UniPoly, Fr> for UniPolyVar {
94 fn new_variable<T: Borrow<UniPoly>>(
95 cs: impl Into<Namespace<Fr>>,
96 f: impl FnOnce() -> Result<T, SynthesisError>,
97 mode: AllocationMode,
98 ) -> Result<Self, SynthesisError> {
99 f().and_then(|c| {
100 let cs = cs.into();
101 let cp: &UniPoly = c.borrow();
102 let mut coeffs_var = Vec::new();
103 for coeff in cp.coeffs.iter() {
104 let coeff_var = FpVar::<Fr>::new_variable(cs.clone(), || Ok(coeff), mode)?;
105 coeffs_var.push(coeff_var);
106 }
107 Ok(Self { coeffs: coeffs_var })
108 })
109 }
110}
111
112impl UniPolyVar {
113 pub fn eval_at_zero(&self) -> FpVar<Fr> {
114 self.coeffs[0].clone()
115 }
116
117 pub fn eval_at_one(&self) -> FpVar<Fr> {
118 let mut res = self.coeffs[0].clone();
119 for i in 1..self.coeffs.len() {
120 res = &res + &self.coeffs[i];
121 }
122 res
123 }
124
125 // mul without reduce
126 pub fn evaluate(&self, r: &FpVar<Fr>) -> FpVar<Fr> {
127 let mut eval = self.coeffs[0].clone();
128 let mut power = r.clone();
129
130 for i in 1..self.coeffs.len() {
131 eval += &power * &self.coeffs[i];
132 power *= r;
133 }
134 eval
135 }
136}
137
138#[derive(Clone)]
139pub struct SumcheckVerificationCircuit {
140 pub polys: Vec<UniPoly>,
141}
142
143impl SumcheckVerificationCircuit {
144 fn verifiy_sumcheck(
145 &self,
146 poly_vars: &[UniPolyVar],
147 claim_var: &FpVar<Fr>,
148 transcript_var: &mut PoseidonTranscripVar,
149 ) -> Result<(FpVar<Fr>, Vec<FpVar<Fr>>), SynthesisError> {
150 let mut e_var = claim_var.clone();
151 let mut r_vars: Vec<FpVar<Fr>> = Vec::new();
152
153 for (poly_var, _poly) in poly_vars.iter().zip(self.polys.iter()) {
154 let res = poly_var.eval_at_one() + poly_var.eval_at_zero();
155 res.enforce_equal(&e_var)?;
156 transcript_var.append_vector(&poly_var.coeffs)?;
157 let r_i_var = transcript_var.challenge()?;
158 r_vars.push(r_i_var.clone());
159 e_var = poly_var.evaluate(&r_i_var.clone());
160 }
161
162 Ok((e_var, r_vars))
163 }
164}
165
166#[derive(Clone)]
167pub struct SparsePolyEntryVar {
168 idx: usize,
169 val_var: FpVar<Fr>,
170}
171
172impl AllocVar<SparsePolyEntry, Fr> for SparsePolyEntryVar {
173 fn new_variable<T: Borrow<SparsePolyEntry>>(
174 cs: impl Into<Namespace<Fr>>,
175 f: impl FnOnce() -> Result<T, SynthesisError>,
176 _mode: AllocationMode,
177 ) -> Result<Self, SynthesisError> {
178 f().and_then(|s| {
179 let cs = cs.into();
180 let spe: &SparsePolyEntry = s.borrow();
181 let val_var = FpVar::<Fr>::new_witness(cs, || Ok(spe.val))?;
182 Ok(Self {
183 idx: spe.idx,
184 val_var,
185 })
186 })
187 }
188}
189
190#[derive(Clone)]
191pub struct SparsePolynomialVar {
192 num_vars: usize,
193 Z_var: Vec<SparsePolyEntryVar>,
194}
195
196impl AllocVar<SparsePolynomial, Fr> for SparsePolynomialVar {
197 fn new_variable<T: Borrow<SparsePolynomial>>(
198 cs: impl Into<Namespace<Fr>>,
199 f: impl FnOnce() -> Result<T, SynthesisError>,
200 mode: AllocationMode,
201 ) -> Result<Self, SynthesisError> {
202 f().and_then(|s| {
203 let cs = cs.into();
204 let sp: &SparsePolynomial = s.borrow();
205 let mut Z_var = Vec::new();
206 for spe in sp.Z.iter() {
207 let spe_var = SparsePolyEntryVar::new_variable(cs.clone(), || Ok(spe), mode)?;
208 Z_var.push(spe_var);
209 }
210 Ok(Self {
211 num_vars: sp.num_vars,
212 Z_var,
213 })
214 })
215 }
216}
217
218impl SparsePolynomialVar {
219 fn compute_chi(a: &[bool], r_vars: &[FpVar<Fr>]) -> FpVar<Fr> {
220 let mut chi_i_var = FpVar::<Fr>::one();
221 let one = FpVar::<Fr>::one();
222 for (i, r_var) in r_vars.iter().enumerate() {
223 if a[i] {
224 chi_i_var *= r_var;
225 } else {
226 chi_i_var *= &one - r_var;
227 }
228 }
229 chi_i_var
230 }
231
232 pub fn evaluate(&self, r_var: &[FpVar<Fr>]) -> FpVar<Fr> {
233 let mut sum = FpVar::<Fr>::zero();
234 for spe_var in self.Z_var.iter() {
235 // potential problem
236 let bits = &spe_var.idx.get_bits(r_var.len());
237 sum += SparsePolynomialVar::compute_chi(bits, r_var) * &spe_var.val_var;
238 }
239 sum
240 }
241}
242
243#[derive(Clone)]
244pub struct R1CSVerificationCircuit {
245 pub num_vars: usize,
246 pub num_cons: usize,
247 pub input: Vec<Fr>,
248 pub input_as_sparse_poly: SparsePolynomial,
249 pub evals: (Fr, Fr, Fr),
250 pub params: PoseidonParameters<Fr>,
251 pub prev_challenge: Fr,
252 pub claims_phase2: (Scalar, Scalar, Scalar, Scalar),
253 pub eval_vars_at_ry: Fr,
254 pub sc_phase1: SumcheckVerificationCircuit,
255 pub sc_phase2: SumcheckVerificationCircuit,
256 // The point on which the polynomial was evaluated by the prover.
257 pub claimed_ry: Vec<Scalar>,
258}
259
260impl R1CSVerificationCircuit {
261 fn new(config: &VerifierConfig) -> Self {
262 Self {
263 num_vars: config.num_vars,
264 num_cons: config.num_cons,
265 input: config.input.clone(),
266 input_as_sparse_poly: config.input_as_sparse_poly.clone(),
267 evals: config.evals,
268 params: config.params.clone(),
269 prev_challenge: config.prev_challenge,
270 claims_phase2: config.claims_phase2,
271 eval_vars_at_ry: config.eval_vars_at_ry,
272 sc_phase1: SumcheckVerificationCircuit {
273 polys: config.polys_sc1.clone(),
274 },
275 sc_phase2: SumcheckVerificationCircuit {
276 polys: config.polys_sc2.clone(),
277 },
278 claimed_ry: config.ry.clone(),
279 }
280 }
281}
282
283impl ConstraintSynthesizer<Fr> for R1CSVerificationCircuit {
284 fn generate_constraints(self, cs: ConstraintSystemRef<Fr>) -> ark_relations::r1cs::Result<()> {
285 let mut transcript_var =
286 PoseidonTranscripVar::new(cs.clone(), &self.params, Some(self.prev_challenge));
287
288 let poly_sc1_vars = self
289 .sc_phase1
290 .polys
291 .iter()
292 .map(|p| UniPolyVar::new_variable(cs.clone(), || Ok(p), AllocationMode::Witness).unwrap())
293 .collect::<Vec<UniPolyVar>>();
294
295 let poly_sc2_vars = self
296 .sc_phase2
297 .polys
298 .iter()
299 .map(|p| UniPolyVar::new_variable(cs.clone(), || Ok(p), AllocationMode::Witness).unwrap())
300 .collect::<Vec<UniPolyVar>>();
301
302 let input_vars = self
303 .input
304 .iter()
305 .map(|i| FpVar::<Fr>::new_variable(cs.clone(), || Ok(i), AllocationMode::Witness).unwrap())
306 .collect::<Vec<FpVar<Fr>>>();
307
308 let claimed_ry_vars = self
309 .claimed_ry
310 .iter()
311 .map(|r| FpVar::<Fr>::new_variable(cs.clone(), || Ok(r), AllocationMode::Input).unwrap())
312 .collect::<Vec<FpVar<Fr>>>();
313
314 transcript_var.append_vector(&input_vars)?;
315
316 let num_rounds_x = self.num_cons.log_2();
317 let _num_rounds_y = (2 * self.num_vars).log_2();
318
319 let tau_vars = transcript_var.challenge_vector(num_rounds_x)?;
320
321 let claim_phase1_var = FpVar::<Fr>::new_witness(cs.clone(), || Ok(Fr::zero()))?;
322
323 let (claim_post_phase1_var, rx_var) =
324 self
325 .sc_phase1
326 .verifiy_sumcheck(&poly_sc1_vars, &claim_phase1_var, &mut transcript_var)?;
327
328 let (Az_claim, Bz_claim, Cz_claim, prod_Az_Bz_claims) = &self.claims_phase2;
329
330 let Az_claim_var = FpVar::<Fr>::new_input(cs.clone(), || Ok(Az_claim))?;
331 let Bz_claim_var = FpVar::<Fr>::new_input(cs.clone(), || Ok(Bz_claim))?;
332 let Cz_claim_var = FpVar::<Fr>::new_input(cs.clone(), || Ok(Cz_claim))?;
333 let prod_Az_Bz_claim_var = FpVar::<Fr>::new_input(cs.clone(), || Ok(prod_Az_Bz_claims))?;
334 let one = FpVar::<Fr>::one();
335 let prod_vars: Vec<FpVar<Fr>> = (0..rx_var.len())
336 .map(|i| (&rx_var[i] * &tau_vars[i]) + (&one - &rx_var[i]) * (&one - &tau_vars[i]))
337 .collect();
338 let mut taus_bound_rx_var = FpVar::<Fr>::one();
339
340 for p_var in prod_vars.iter() {
341 taus_bound_rx_var *= p_var;
342 }
343
344 let expected_claim_post_phase1_var =
345 (&prod_Az_Bz_claim_var - &Cz_claim_var) * &taus_bound_rx_var;
346
347 claim_post_phase1_var.enforce_equal(&expected_claim_post_phase1_var)?;
348
349 let r_A_var = transcript_var.challenge()?;
350 let r_B_var = transcript_var.challenge()?;
351 let r_C_var = transcript_var.challenge()?;
352
353 let claim_phase2_var =
354 &r_A_var * &Az_claim_var + &r_B_var * &Bz_claim_var + &r_C_var * &Cz_claim_var;
355
356 let (claim_post_phase2_var, ry_var) =
357 self
358 .sc_phase2
359 .verifiy_sumcheck(&poly_sc2_vars, &claim_phase2_var, &mut transcript_var)?;
360
361 // Because the verifier checks the commitment opening on point ry outside
362 // the circuit, the prover needs to send ry to the verifier (making the
363 // proof size O(log n)). As this point is normally obtained by the verifier
364 // from the second round of sumcheck, the circuit needs to ensure the
365 // claimed point, coming from the prover, is actually the point derived
366 // inside the circuit. These additional checks will be removed
367 // when the commitment verification is done inside the circuit.
368 for (i, r) in claimed_ry_vars.iter().enumerate() {
369 ry_var[i].enforce_equal(r)?;
370 }
371
372 let input_as_sparse_poly_var = SparsePolynomialVar::new_variable(
373 cs.clone(),
374 || Ok(&self.input_as_sparse_poly),
375 AllocationMode::Witness,
376 )?;
377
378 let poly_input_eval_var = input_as_sparse_poly_var.evaluate(&ry_var[1..]);
379
380 let eval_vars_at_ry_var = FpVar::<Fr>::new_input(cs.clone(), || Ok(&self.eval_vars_at_ry))?;
381
382 let eval_Z_at_ry_var =
383 (FpVar::<Fr>::one() - &ry_var[0]) * &eval_vars_at_ry_var + &ry_var[0] * &poly_input_eval_var;
384
385 let (eval_A_r, eval_B_r, eval_C_r) = self.evals;
386
387 let eval_A_r_var = FpVar::<Fr>::new_witness(cs.clone(), || Ok(eval_A_r))?;
388 let eval_B_r_var = FpVar::<Fr>::new_witness(cs.clone(), || Ok(eval_B_r))?;
389 let eval_C_r_var = FpVar::<Fr>::new_witness(cs, || Ok(eval_C_r))?;
390
391 let scalar_var = &r_A_var * &eval_A_r_var + &r_B_var * &eval_B_r_var + &r_C_var * &eval_C_r_var;
392
393 let expected_claim_post_phase2_var = eval_Z_at_ry_var * scalar_var;
394 claim_post_phase2_var.enforce_equal(&expected_claim_post_phase2_var)?;
395
396 Ok(())
397 }
398}
399
400#[derive(Clone)]
401pub struct VerifierConfig {
402 pub num_vars: usize,
403 pub num_cons: usize,
404 pub input: Vec<Fr>,
405 pub input_as_sparse_poly: SparsePolynomial,
406 pub evals: (Fr, Fr, Fr),
407 pub params: PoseidonParameters<Fr>,
408 pub prev_challenge: Fr,
409 pub claims_phase2: (Fr, Fr, Fr, Fr),
410 pub eval_vars_at_ry: Fr,
411 pub polys_sc1: Vec<UniPoly>,
412 pub polys_sc2: Vec<UniPoly>,
413 pub ry: Vec<Scalar>,
414}
415#[derive(Clone)]
416pub struct VerifierCircuit {
417 pub inner_circuit: R1CSVerificationCircuit,
418 pub inner_proof: GrothProof<I>,
419 pub inner_vk: PreparedVerifyingKey<I>,
420 pub eval_vars_at_ry: Fr,
421 pub claims_phase2: (Fr, Fr, Fr, Fr),
422 pub ry: Vec<Fr>,
423}
424
425impl VerifierCircuit {
426 pub fn new<R: Rng + CryptoRng>(
427 config: &VerifierConfig,
428 mut rng: &mut R,
429 ) -> Result<Self, SynthesisError> {
430 let inner_circuit = R1CSVerificationCircuit::new(config);
431 let (pk, vk) = Groth16::<I>::setup(inner_circuit.clone(), &mut rng).unwrap();
432 let proof = Groth16::<I>::prove(&pk, inner_circuit.clone(), &mut rng)?;
433 let pvk = Groth16::<I>::process_vk(&vk).unwrap();
434 Ok(Self {
435 inner_circuit,
436 inner_proof: proof,
437 inner_vk: pvk,
438 eval_vars_at_ry: config.eval_vars_at_ry,
439 claims_phase2: config.claims_phase2,
440 ry: config.ry.clone(),
441 })
442 }
443}
444
445impl ConstraintSynthesizer<Fq> for VerifierCircuit {
446 fn generate_constraints(self, cs: ConstraintSystemRef<Fq>) -> ark_relations::r1cs::Result<()> {
447 let proof_var = ProofVar::<I, IV>::new_witness(cs.clone(), || Ok(self.inner_proof.clone()))?;
448 let (v_A, v_B, v_C, v_AB) = self.claims_phase2;
449 let mut pubs = vec![];
450 pubs.extend(self.ry);
451 pubs.extend(vec![v_A, v_B, v_C, v_AB]);
452 pubs.extend(vec![self.eval_vars_at_ry]);
453 let bits = pubs
454 .iter()
455 .map(|c| {
456 let bits: Vec<bool> = BitIteratorLE::new(c.into_repr().as_ref().to_vec()).collect();
457 Vec::new_witness(cs.clone(), || Ok(bits))
458 })
459 .collect::<Result<Vec<_>, _>>()?;
460 let input_var = BooleanInputVar::<Fr, Fq>::new(bits);
461
462 let vk_var = PreparedVerifyingKeyVar::new_witness(cs, || Ok(self.inner_vk.clone()))?;
463 Groth16VerifierGadget::verify_with_processed_vk(&vk_var, &input_var, &proof_var)?
464 .enforce_equal(&Boolean::constant(true))?;
465 Ok(())
466 }
467}