sonobe/folding-schemes/src/folding/nova/decider_eth_circuit.rs
folding-schemes/src/folding/nova/decider_eth_circuit.rsRaw
1/// This file implements the onchain (Ethereum's EVM) decider circuit. For non-ethereum use cases,
2/// other more efficient approaches can be used.
3use ark_crypto_primitives::crh::poseidon::constraints::CRHParametersVar;
4use ark_crypto_primitives::sponge::{poseidon::PoseidonConfig, Absorb};
5use ark_ec::{CurveGroup, Group};
6use ark_ff::{BigInteger, PrimeField};
7use ark_poly::Polynomial;
8use ark_r1cs_std::{
9 alloc::{AllocVar, AllocationMode},
10 boolean::Boolean,
11 eq::EqGadget,
12 fields::{fp::FpVar, FieldVar},
13 groups::GroupOpsBounds,
14 poly::{domain::Radix2DomainVar, evaluations::univariate::EvaluationsVar},
15 prelude::CurveVar,
16 ToConstraintFieldGadget,
17};
18use ark_relations::r1cs::{ConstraintSynthesizer, ConstraintSystemRef, Namespace, SynthesisError};
19use ark_std::{log2, Zero};
20use core::{borrow::Borrow, marker::PhantomData};
21
22use super::{circuits::ChallengeGadget, nifs::NIFS};
23use crate::arith::r1cs::R1CS;
24use crate::commitment::{pedersen::Params as PedersenParams, CommitmentScheme};
25use crate::folding::circuits::{
26 nonnative::{
27 affine::{nonnative_affine_to_field_elements, NonNativeAffineVar},
28 uint::NonNativeUintVar,
29 },
30 CF1, CF2,
31};
32use crate::folding::nova::{circuits::CommittedInstanceVar, CommittedInstance, Nova, Witness};
33use crate::frontend::FCircuit;
34use crate::transcript::{
35 poseidon::{PoseidonTranscript, PoseidonTranscriptVar},
36 Transcript, TranscriptVar,
37};
38use crate::utils::{
39 gadgets::{MatrixGadget, SparseMatrixVar, VectorGadget},
40 vec::poly_from_vec,
41};
42use crate::Error;
43
44#[derive(Debug, Clone)]
45pub struct RelaxedR1CSGadget {}
46impl RelaxedR1CSGadget {
47 /// performs the RelaxedR1CS check for native variables (Az∘Bz==uCz+E)
48 pub fn check_native<F: PrimeField>(
49 r1cs: R1CSVar<F, F, FpVar<F>>,
50 E: Vec<FpVar<F>>,
51 u: FpVar<F>,
52 z: Vec<FpVar<F>>,
53 ) -> Result<(), SynthesisError> {
54 let Az = r1cs.A.mul_vector(&z)?;
55 let Bz = r1cs.B.mul_vector(&z)?;
56 let Cz = r1cs.C.mul_vector(&z)?;
57 let uCzE = Cz.mul_scalar(&u)?.add(&E)?;
58 let AzBz = Az.hadamard(&Bz)?;
59 AzBz.enforce_equal(&uCzE)?;
60 Ok(())
61 }
62
63 /// performs the RelaxedR1CS check for non-native variables (Az∘Bz==uCz+E)
64 pub fn check_nonnative<F: PrimeField, CF: PrimeField>(
65 r1cs: R1CSVar<F, CF, NonNativeUintVar<CF>>,
66 E: Vec<NonNativeUintVar<CF>>,
67 u: NonNativeUintVar<CF>,
68 z: Vec<NonNativeUintVar<CF>>,
69 ) -> Result<(), SynthesisError> {
70 // First we do addition and multiplication without mod F's order
71 let Az = r1cs.A.mul_vector(&z)?;
72 let Bz = r1cs.B.mul_vector(&z)?;
73 let Cz = r1cs.C.mul_vector(&z)?;
74 let uCzE = Cz.mul_scalar(&u)?.add(&E)?;
75 let AzBz = Az.hadamard(&Bz)?;
76
77 // Then we compare the results by checking if they are congruent
78 // modulo the field order
79 AzBz.into_iter()
80 .zip(uCzE)
81 .try_for_each(|(a, b)| a.enforce_congruent::<F>(&b))
82 }
83}
84
85#[derive(Debug, Clone)]
86pub struct R1CSVar<F: PrimeField, CF: PrimeField, FV: AllocVar<F, CF>> {
87 _f: PhantomData<F>,
88 _cf: PhantomData<CF>,
89 _fv: PhantomData<FV>,
90 pub A: SparseMatrixVar<F, CF, FV>,
91 pub B: SparseMatrixVar<F, CF, FV>,
92 pub C: SparseMatrixVar<F, CF, FV>,
93}
94
95impl<F, CF, FV> AllocVar<R1CS<F>, CF> for R1CSVar<F, CF, FV>
96where
97 F: PrimeField,
98 CF: PrimeField,
99 FV: AllocVar<F, CF>,
100{
101 fn new_variable<T: Borrow<R1CS<F>>>(
102 cs: impl Into<Namespace<CF>>,
103 f: impl FnOnce() -> Result<T, SynthesisError>,
104 _mode: AllocationMode,
105 ) -> Result<Self, SynthesisError> {
106 f().and_then(|val| {
107 let cs = cs.into();
108
109 let A = SparseMatrixVar::<F, CF, FV>::new_constant(cs.clone(), &val.borrow().A)?;
110 let B = SparseMatrixVar::<F, CF, FV>::new_constant(cs.clone(), &val.borrow().B)?;
111 let C = SparseMatrixVar::<F, CF, FV>::new_constant(cs.clone(), &val.borrow().C)?;
112
113 Ok(Self {
114 _f: PhantomData,
115 _cf: PhantomData,
116 _fv: PhantomData,
117 A,
118 B,
119 C,
120 })
121 })
122 }
123}
124
125/// In-circuit representation of the Witness associated to the CommittedInstance.
126#[derive(Debug, Clone)]
127pub struct WitnessVar<C: CurveGroup> {
128 pub E: Vec<FpVar<C::ScalarField>>,
129 pub rE: FpVar<C::ScalarField>,
130 pub W: Vec<FpVar<C::ScalarField>>,
131 pub rW: FpVar<C::ScalarField>,
132}
133
134impl<C> AllocVar<Witness<C>, CF1<C>> for WitnessVar<C>
135where
136 C: CurveGroup,
137 <C as ark_ec::CurveGroup>::BaseField: PrimeField,
138{
139 fn new_variable<T: Borrow<Witness<C>>>(
140 cs: impl Into<Namespace<CF1<C>>>,
141 f: impl FnOnce() -> Result<T, SynthesisError>,
142 mode: AllocationMode,
143 ) -> Result<Self, SynthesisError> {
144 f().and_then(|val| {
145 let cs = cs.into();
146
147 let E: Vec<FpVar<C::ScalarField>> =
148 Vec::new_variable(cs.clone(), || Ok(val.borrow().E.clone()), mode)?;
149 let rE =
150 FpVar::<C::ScalarField>::new_variable(cs.clone(), || Ok(val.borrow().rE), mode)?;
151
152 let W: Vec<FpVar<C::ScalarField>> =
153 Vec::new_variable(cs.clone(), || Ok(val.borrow().W.clone()), mode)?;
154 let rW =
155 FpVar::<C::ScalarField>::new_variable(cs.clone(), || Ok(val.borrow().rW), mode)?;
156
157 Ok(Self { E, rE, W, rW })
158 })
159 }
160}
161
162/// In-circuit representation of the Witness associated to the CommittedInstance, but with
163/// non-native representation, since it is used to represent the CycleFold witness.
164#[derive(Debug, Clone)]
165pub struct CycleFoldWitnessVar<C: CurveGroup> {
166 pub E: Vec<NonNativeUintVar<CF2<C>>>,
167 pub rE: NonNativeUintVar<CF2<C>>,
168 pub W: Vec<NonNativeUintVar<CF2<C>>>,
169 pub rW: NonNativeUintVar<CF2<C>>,
170}
171
172impl<C> AllocVar<Witness<C>, CF2<C>> for CycleFoldWitnessVar<C>
173where
174 C: CurveGroup,
175 <C as ark_ec::CurveGroup>::BaseField: PrimeField,
176{
177 fn new_variable<T: Borrow<Witness<C>>>(
178 cs: impl Into<Namespace<CF2<C>>>,
179 f: impl FnOnce() -> Result<T, SynthesisError>,
180 mode: AllocationMode,
181 ) -> Result<Self, SynthesisError> {
182 f().and_then(|val| {
183 let cs = cs.into();
184
185 let E = Vec::new_variable(cs.clone(), || Ok(val.borrow().E.clone()), mode)?;
186 let rE = NonNativeUintVar::new_variable(cs.clone(), || Ok(val.borrow().rE), mode)?;
187
188 let W = Vec::new_variable(cs.clone(), || Ok(val.borrow().W.clone()), mode)?;
189 let rW = NonNativeUintVar::new_variable(cs.clone(), || Ok(val.borrow().rW), mode)?;
190
191 Ok(Self { E, rE, W, rW })
192 })
193 }
194}
195
196/// Circuit that implements the in-circuit checks needed for the onchain (Ethereum's EVM)
197/// verification.
198#[derive(Clone, Debug)]
199pub struct DeciderEthCircuit<C1, GC1, C2, GC2, CS1, CS2>
200where
201 C1: CurveGroup,
202 GC1: CurveVar<C1, CF2<C1>>,
203 C2: CurveGroup,
204 GC2: CurveVar<C2, CF2<C2>>,
205 CS1: CommitmentScheme<C1>,
206 CS2: CommitmentScheme<C2>,
207{
208 _c1: PhantomData<C1>,
209 _gc1: PhantomData<GC1>,
210 _c2: PhantomData<C2>,
211 _gc2: PhantomData<GC2>,
212 _cs1: PhantomData<CS1>,
213 _cs2: PhantomData<CS2>,
214
215 /// E vector's length of the Nova instance witness
216 pub E_len: usize,
217 /// E vector's length of the CycleFold instance witness
218 pub cf_E_len: usize,
219 /// R1CS of the Augmented Function circuit
220 pub r1cs: R1CS<C1::ScalarField>,
221 /// R1CS of the CycleFold circuit
222 pub cf_r1cs: R1CS<C2::ScalarField>,
223 /// CycleFold PedersenParams over C2
224 pub cf_pedersen_params: PedersenParams<C2>,
225 pub poseidon_config: PoseidonConfig<CF1<C1>>,
226 /// public params hash
227 pub pp_hash: Option<C1::ScalarField>,
228 pub i: Option<CF1<C1>>,
229 /// initial state
230 pub z_0: Option<Vec<C1::ScalarField>>,
231 /// current i-th state
232 pub z_i: Option<Vec<C1::ScalarField>>,
233 /// Nova instances
234 pub u_i: Option<CommittedInstance<C1>>,
235 pub w_i: Option<Witness<C1>>,
236 pub U_i: Option<CommittedInstance<C1>>,
237 pub W_i: Option<Witness<C1>>,
238 pub U_i1: Option<CommittedInstance<C1>>,
239 pub W_i1: Option<Witness<C1>>,
240 pub cmT: Option<C1>,
241 pub r: Option<C1::ScalarField>,
242 /// CycleFold running instance
243 pub cf_U_i: Option<CommittedInstance<C2>>,
244 pub cf_W_i: Option<Witness<C2>>,
245
246 /// KZG challenges
247 pub kzg_c_W: Option<C1::ScalarField>,
248 pub kzg_c_E: Option<C1::ScalarField>,
249 pub eval_W: Option<C1::ScalarField>,
250 pub eval_E: Option<C1::ScalarField>,
251}
252impl<C1, GC1, C2, GC2, CS1, CS2> DeciderEthCircuit<C1, GC1, C2, GC2, CS1, CS2>
253where
254 C1: CurveGroup,
255 C2: CurveGroup,
256 GC1: CurveVar<C1, CF2<C1>> + ToConstraintFieldGadget<CF2<C1>>,
257 GC2: CurveVar<C2, CF2<C2>> + ToConstraintFieldGadget<CF2<C2>>,
258 CS1: CommitmentScheme<C1>,
259 // enforce that the CS2 is Pedersen commitment scheme, since we're at Ethereum's EVM decider
260 CS2: CommitmentScheme<C2, ProverParams = PedersenParams<C2>>,
261 <C1 as Group>::ScalarField: Absorb,
262 <C1 as CurveGroup>::BaseField: PrimeField,
263{
264 pub fn from_nova<FC: FCircuit<C1::ScalarField>>(
265 nova: Nova<C1, GC1, C2, GC2, FC, CS1, CS2>,
266 ) -> Result<Self, Error> {
267 // compute the U_{i+1}, W_{i+1}
268 let (T, cmT) = NIFS::<C1, CS1>::compute_cmT(
269 &nova.cs_pp,
270 &nova.r1cs.clone(),
271 &nova.w_i.clone(),
272 &nova.u_i.clone(),
273 &nova.W_i.clone(),
274 &nova.U_i.clone(),
275 )?;
276 let r_bits = ChallengeGadget::<C1>::get_challenge_native(
277 &nova.poseidon_config,
278 nova.pp_hash,
279 nova.U_i.clone(),
280 nova.u_i.clone(),
281 cmT,
282 )?;
283 let r_Fr = C1::ScalarField::from_bigint(BigInteger::from_bits_le(&r_bits))
284 .ok_or(Error::OutOfBounds)?;
285 let (W_i1, U_i1) = NIFS::<C1, CS1>::fold_instances(
286 r_Fr, &nova.W_i, &nova.U_i, &nova.w_i, &nova.u_i, &T, cmT,
287 )?;
288
289 // compute the KZG challenges used as inputs in the circuit
290 let (kzg_challenge_W, kzg_challenge_E) =
291 KZGChallengesGadget::<C1>::get_challenges_native(&nova.poseidon_config, U_i1.clone())?;
292
293 // get KZG evals
294 let mut W = W_i1.W.clone();
295 W.extend(
296 std::iter::repeat(C1::ScalarField::zero())
297 .take(W_i1.W.len().next_power_of_two() - W_i1.W.len()),
298 );
299 let mut E = W_i1.E.clone();
300 E.extend(
301 std::iter::repeat(C1::ScalarField::zero())
302 .take(W_i1.E.len().next_power_of_two() - W_i1.E.len()),
303 );
304 let p_W = poly_from_vec(W.to_vec())?;
305 let eval_W = p_W.evaluate(&kzg_challenge_W);
306 let p_E = poly_from_vec(E.to_vec())?;
307 let eval_E = p_E.evaluate(&kzg_challenge_E);
308
309 Ok(Self {
310 _c1: PhantomData,
311 _gc1: PhantomData,
312 _c2: PhantomData,
313 _gc2: PhantomData,
314 _cs1: PhantomData,
315 _cs2: PhantomData,
316
317 E_len: nova.W_i.E.len(),
318 cf_E_len: nova.cf_W_i.E.len(),
319 r1cs: nova.r1cs,
320 cf_r1cs: nova.cf_r1cs,
321 cf_pedersen_params: nova.cf_cs_pp,
322 poseidon_config: nova.poseidon_config,
323 pp_hash: Some(nova.pp_hash),
324 i: Some(nova.i),
325 z_0: Some(nova.z_0),
326 z_i: Some(nova.z_i),
327 u_i: Some(nova.u_i),
328 w_i: Some(nova.w_i),
329 U_i: Some(nova.U_i),
330 W_i: Some(nova.W_i),
331 U_i1: Some(U_i1),
332 W_i1: Some(W_i1),
333 cmT: Some(cmT),
334 r: Some(r_Fr),
335 cf_U_i: Some(nova.cf_U_i),
336 cf_W_i: Some(nova.cf_W_i),
337 kzg_c_W: Some(kzg_challenge_W),
338 kzg_c_E: Some(kzg_challenge_E),
339 eval_W: Some(eval_W),
340 eval_E: Some(eval_E),
341 })
342 }
343}
344
345impl<C1, GC1, C2, GC2, CS1, CS2> ConstraintSynthesizer<CF1<C1>>
346 for DeciderEthCircuit<C1, GC1, C2, GC2, CS1, CS2>
347where
348 C1: CurveGroup,
349 C2: CurveGroup,
350 GC1: CurveVar<C1, CF2<C1>>,
351 GC2: CurveVar<C2, CF2<C2>> + ToConstraintFieldGadget<CF2<C2>>,
352 CS1: CommitmentScheme<C1>,
353 CS2: CommitmentScheme<C2>,
354 <C1 as CurveGroup>::BaseField: PrimeField,
355 <C2 as CurveGroup>::BaseField: PrimeField,
356 <C1 as Group>::ScalarField: Absorb,
357 <C2 as Group>::ScalarField: Absorb,
358 C1: CurveGroup<BaseField = C2::ScalarField, ScalarField = C2::BaseField>,
359 for<'b> &'b GC2: GroupOpsBounds<'b, C2, GC2>,
360{
361 fn generate_constraints(self, cs: ConstraintSystemRef<CF1<C1>>) -> Result<(), SynthesisError> {
362 let r1cs =
363 R1CSVar::<C1::ScalarField, CF1<C1>, FpVar<CF1<C1>>>::new_witness(cs.clone(), || {
364 Ok(self.r1cs.clone())
365 })?;
366
367 let pp_hash = FpVar::<CF1<C1>>::new_input(cs.clone(), || {
368 Ok(self.pp_hash.unwrap_or_else(CF1::<C1>::zero))
369 })?;
370 let i =
371 FpVar::<CF1<C1>>::new_input(cs.clone(), || Ok(self.i.unwrap_or_else(CF1::<C1>::zero)))?;
372 let z_0 = Vec::<FpVar<CF1<C1>>>::new_input(cs.clone(), || {
373 Ok(self.z_0.unwrap_or(vec![CF1::<C1>::zero()]))
374 })?;
375 let z_i = Vec::<FpVar<CF1<C1>>>::new_input(cs.clone(), || {
376 Ok(self.z_i.unwrap_or(vec![CF1::<C1>::zero()]))
377 })?;
378
379 let u_dummy_native = CommittedInstance::<C1>::dummy(2);
380 let w_dummy_native = Witness::<C1>::new(
381 vec![C1::ScalarField::zero(); self.r1cs.A.n_cols - 3 /* (3=2+1, since u_i.x.len=2) */],
382 self.E_len,
383 );
384
385 let u_i = CommittedInstanceVar::<C1>::new_witness(cs.clone(), || {
386 Ok(self.u_i.unwrap_or(u_dummy_native.clone()))
387 })?;
388 let U_i = CommittedInstanceVar::<C1>::new_witness(cs.clone(), || {
389 Ok(self.U_i.unwrap_or(u_dummy_native.clone()))
390 })?;
391 // here (U_i1, W_i1) = NIFS.P( (U_i,W_i), (u_i,w_i))
392 let U_i1 = CommittedInstanceVar::<C1>::new_input(cs.clone(), || {
393 Ok(self.U_i1.unwrap_or(u_dummy_native.clone()))
394 })?;
395 let W_i1 = WitnessVar::<C1>::new_witness(cs.clone(), || {
396 Ok(self.W_i1.unwrap_or(w_dummy_native.clone()))
397 })?;
398
399 // allocate the inputs for the check 6
400 let kzg_c_W = FpVar::<CF1<C1>>::new_input(cs.clone(), || {
401 Ok(self.kzg_c_W.unwrap_or_else(CF1::<C1>::zero))
402 })?;
403 let kzg_c_E = FpVar::<CF1<C1>>::new_input(cs.clone(), || {
404 Ok(self.kzg_c_E.unwrap_or_else(CF1::<C1>::zero))
405 })?;
406 let _eval_W = FpVar::<CF1<C1>>::new_input(cs.clone(), || {
407 Ok(self.eval_W.unwrap_or_else(CF1::<C1>::zero))
408 })?;
409 let _eval_E = FpVar::<CF1<C1>>::new_input(cs.clone(), || {
410 Ok(self.eval_E.unwrap_or_else(CF1::<C1>::zero))
411 })?;
412
413 let crh_params = CRHParametersVar::<C1::ScalarField>::new_constant(
414 cs.clone(),
415 self.poseidon_config.clone(),
416 )?;
417
418 // 1. check RelaxedR1CS of U_{i+1}
419 let z_U1: Vec<FpVar<CF1<C1>>> =
420 [vec![U_i1.u.clone()], U_i1.x.to_vec(), W_i1.W.to_vec()].concat();
421 RelaxedR1CSGadget::check_native(r1cs, W_i1.E.clone(), U_i1.u.clone(), z_U1)?;
422
423 // 2. u_i.cmE==cm(0), u_i.u==1
424 // Here zero is the x & y coordinates of the zero point affine representation.
425 let zero = NonNativeUintVar::new_constant(cs.clone(), C1::BaseField::zero())?;
426 u_i.cmE.x.enforce_equal_unaligned(&zero)?;
427 u_i.cmE.y.enforce_equal_unaligned(&zero)?;
428 (u_i.u.is_one()?).enforce_equal(&Boolean::TRUE)?;
429
430 // 3.a u_i.x[0] == H(i, z_0, z_i, U_i)
431 let (u_i_x, U_i_vec) = U_i.clone().hash(
432 &crh_params,
433 pp_hash.clone(),
434 i.clone(),
435 z_0.clone(),
436 z_i.clone(),
437 )?;
438 (u_i.x[0]).enforce_equal(&u_i_x)?;
439
440 #[cfg(feature = "light-test")]
441 println!("[WARNING]: Running with the 'light-test' feature, skipping the big part of the DeciderEthCircuit.\n Only for testing purposes.");
442
443 // The following two checks (and their respective allocations) are disabled for normal
444 // tests since they take several millions of constraints and would take several minutes
445 // (and RAM) to run the test. It is active by default, and not active only when
446 // 'light-test' feature is used.
447 #[cfg(not(feature = "light-test"))]
448 {
449 // imports here instead of at the top of the file, so we avoid having multiple
450 // `#[cfg(not(test))]`
451 use crate::commitment::pedersen::PedersenGadget;
452 use crate::folding::circuits::cyclefold::{CycleFoldCommittedInstanceVar, CF_IO_LEN};
453 use ark_r1cs_std::ToBitsGadget;
454
455 let cf_u_dummy_native = CommittedInstance::<C2>::dummy(CF_IO_LEN);
456 let w_dummy_native = Witness::<C2>::new(
457 vec![C2::ScalarField::zero(); self.cf_r1cs.A.n_cols - 1 - self.cf_r1cs.l],
458 self.cf_E_len,
459 );
460 let cf_U_i = CycleFoldCommittedInstanceVar::<C2, GC2>::new_witness(cs.clone(), || {
461 Ok(self.cf_U_i.unwrap_or_else(|| cf_u_dummy_native.clone()))
462 })?;
463 let cf_W_i = CycleFoldWitnessVar::<C2>::new_witness(cs.clone(), || {
464 Ok(self.cf_W_i.unwrap_or(w_dummy_native.clone()))
465 })?;
466
467 // 3.b u_i.x[1] == H(cf_U_i)
468 let (cf_u_i_x, _) = cf_U_i.clone().hash(&crh_params, pp_hash.clone())?;
469 (u_i.x[1]).enforce_equal(&cf_u_i_x)?;
470
471 // 4. check Pedersen commitments of cf_U_i.{cmE, cmW}
472 let H = GC2::new_constant(cs.clone(), self.cf_pedersen_params.h)?;
473 let G = Vec::<GC2>::new_constant(cs.clone(), self.cf_pedersen_params.generators)?;
474 let cf_W_i_E_bits: Result<Vec<Vec<Boolean<CF1<C1>>>>, SynthesisError> =
475 cf_W_i.E.iter().map(|E_i| E_i.to_bits_le()).collect();
476 let cf_W_i_W_bits: Result<Vec<Vec<Boolean<CF1<C1>>>>, SynthesisError> =
477 cf_W_i.W.iter().map(|W_i| W_i.to_bits_le()).collect();
478
479 let computed_cmE = PedersenGadget::<C2, GC2>::commit(
480 H.clone(),
481 G.clone(),
482 cf_W_i_E_bits?,
483 cf_W_i.rE.to_bits_le()?,
484 )?;
485 cf_U_i.cmE.enforce_equal(&computed_cmE)?;
486 let computed_cmW =
487 PedersenGadget::<C2, GC2>::commit(H, G, cf_W_i_W_bits?, cf_W_i.rW.to_bits_le()?)?;
488 cf_U_i.cmW.enforce_equal(&computed_cmW)?;
489
490 let cf_r1cs =
491 R1CSVar::<C1::BaseField, CF1<C1>, NonNativeUintVar<CF1<C1>>>::new_witness(
492 cs.clone(),
493 || Ok(self.cf_r1cs.clone()),
494 )?;
495
496 // 5. check RelaxedR1CS of cf_U_i
497 let cf_z_U = [vec![cf_U_i.u.clone()], cf_U_i.x.to_vec(), cf_W_i.W.to_vec()].concat();
498 RelaxedR1CSGadget::check_nonnative(cf_r1cs, cf_W_i.E, cf_U_i.u.clone(), cf_z_U)?;
499 }
500
501 // 6. check KZG challenges
502 let (incircuit_c_W, incircuit_c_E) = KZGChallengesGadget::<C1>::get_challenges_gadget(
503 cs.clone(),
504 &self.poseidon_config,
505 U_i1.clone(),
506 )?;
507 incircuit_c_W.enforce_equal(&kzg_c_W)?;
508 incircuit_c_E.enforce_equal(&kzg_c_E)?;
509
510 // Check 7 is temporary disabled due
511 // https://github.com/privacy-scaling-explorations/sonobe/issues/80
512 //
513 // 7. check eval_W==p_W(c_W) and eval_E==p_E(c_E)
514 // let incircuit_eval_W = evaluate_gadget::<CF1<C1>>(W_i1.W, incircuit_c_W)?;
515 // let incircuit_eval_E = evaluate_gadget::<CF1<C1>>(W_i1.E, incircuit_c_E)?;
516 // incircuit_eval_W.enforce_equal(&eval_W)?;
517 // incircuit_eval_E.enforce_equal(&eval_E)?;
518
519 // 8. compute the NIFS.V challenge and check that matches the one from the public input (so we
520 // avoid the verifier computing it)
521 let cmT =
522 NonNativeAffineVar::new_input(cs.clone(), || Ok(self.cmT.unwrap_or_else(C1::zero)))?;
523 let r_bits = ChallengeGadget::<C1>::get_challenge_gadget(
524 cs.clone(),
525 &self.poseidon_config,
526 pp_hash,
527 U_i_vec,
528 u_i.clone(),
529 cmT.clone(),
530 )?;
531 let r_Fr = Boolean::le_bits_to_fp_var(&r_bits)?;
532 // check that the in-circuit computed r is equal to the inputted r
533 let r =
534 FpVar::<CF1<C1>>::new_input(cs.clone(), || Ok(self.r.unwrap_or_else(CF1::<C1>::zero)))?;
535 r_Fr.enforce_equal(&r)?;
536
537 Ok(())
538 }
539}
540
541/// Interpolates the polynomial from the given vector, and then returns it's evaluation at the
542/// given point.
543#[allow(unused)] // unused while check 7 is disabled
544fn evaluate_gadget<F: PrimeField>(
545 v: Vec<FpVar<F>>,
546 point: FpVar<F>,
547) -> Result<FpVar<F>, SynthesisError> {
548 if !v.len().is_power_of_two() {
549 return Err(SynthesisError::Unsatisfiable);
550 }
551 let n = v.len() as u64;
552 let gen = F::get_root_of_unity(n).unwrap();
553 let domain = Radix2DomainVar::new(gen, log2(v.len()) as u64, FpVar::one()).unwrap();
554
555 let evaluations_var = EvaluationsVar::from_vec_and_domain(v, domain, true);
556 evaluations_var.interpolate_and_evaluate(&point)
557}
558
559/// Gadget that computes the KZG challenges, also offers the rust native implementation compatible
560/// with the gadget.
561pub struct KZGChallengesGadget<C: CurveGroup> {
562 _c: PhantomData<C>,
563}
564#[allow(clippy::type_complexity)]
565impl<C> KZGChallengesGadget<C>
566where
567 C: CurveGroup,
568 C::ScalarField: PrimeField,
569 <C as CurveGroup>::BaseField: PrimeField,
570 C::ScalarField: Absorb,
571{
572 pub fn get_challenges_native(
573 poseidon_config: &PoseidonConfig<C::ScalarField>,
574 U_i: CommittedInstance<C>,
575 ) -> Result<(C::ScalarField, C::ScalarField), Error> {
576 let (cmE_x_limbs, cmE_y_limbs) = nonnative_affine_to_field_elements(U_i.cmE)?;
577 let (cmW_x_limbs, cmW_y_limbs) = nonnative_affine_to_field_elements(U_i.cmW)?;
578
579 let transcript = &mut PoseidonTranscript::<C>::new(poseidon_config);
580 // compute the KZG challenges, which are computed in-circuit and checked that it matches
581 // the inputted one
582 transcript.absorb_vec(&cmW_x_limbs);
583 transcript.absorb_vec(&cmW_y_limbs);
584 let challenge_W = transcript.get_challenge();
585 transcript.absorb_vec(&cmE_x_limbs);
586 transcript.absorb_vec(&cmE_y_limbs);
587 let challenge_E = transcript.get_challenge();
588
589 Ok((challenge_W, challenge_E))
590 }
591 // compatible with the native get_challenges_native
592 pub fn get_challenges_gadget(
593 cs: ConstraintSystemRef<C::ScalarField>,
594 poseidon_config: &PoseidonConfig<C::ScalarField>,
595 U_i: CommittedInstanceVar<C>,
596 ) -> Result<(FpVar<C::ScalarField>, FpVar<C::ScalarField>), SynthesisError> {
597 let mut transcript =
598 PoseidonTranscriptVar::<CF1<C>>::new(cs.clone(), &poseidon_config.clone());
599
600 transcript.absorb_vec(&U_i.cmW.to_constraint_field()?[..])?;
601 let challenge_W = transcript.get_challenge()?;
602
603 transcript.absorb_vec(&U_i.cmE.to_constraint_field()?[..])?;
604 let challenge_E = transcript.get_challenge()?;
605
606 Ok((challenge_W, challenge_E))
607 }
608}
609
610#[cfg(test)]
611pub mod tests {
612 use ark_crypto_primitives::crh::{
613 sha256::{
614 constraints::{Sha256Gadget, UnitVar},
615 Sha256,
616 },
617 CRHScheme, CRHSchemeGadget,
618 };
619 use ark_pallas::{constraints::GVar, Fq, Fr, Projective};
620 use ark_r1cs_std::bits::uint8::UInt8;
621 use ark_relations::r1cs::ConstraintSystem;
622 use ark_std::{One, UniformRand};
623 use ark_vesta::{constraints::GVar as GVar2, Projective as Projective2};
624
625 use super::*;
626 use crate::arith::{
627 r1cs::{
628 tests::{get_test_r1cs, get_test_z},
629 {extract_r1cs, extract_w_x},
630 },
631 Arith,
632 };
633 use crate::commitment::pedersen::Pedersen;
634 use crate::folding::nova::PreprocessorParam;
635 use crate::frontend::tests::{CubicFCircuit, CustomFCircuit, WrapperCircuit};
636 use crate::transcript::poseidon::poseidon_canonical_config;
637 use crate::FoldingScheme;
638
639 #[test]
640 fn test_relaxed_r1cs_small_gadget_handcrafted() {
641 let r1cs: R1CS<Fr> = get_test_r1cs();
642 let rel_r1cs = r1cs.clone().relax();
643 let z = get_test_z(3);
644
645 let cs = ConstraintSystem::<Fr>::new_ref();
646
647 let zVar = Vec::<FpVar<Fr>>::new_witness(cs.clone(), || Ok(z)).unwrap();
648 let EVar = Vec::<FpVar<Fr>>::new_witness(cs.clone(), || Ok(rel_r1cs.E)).unwrap();
649 let uVar = FpVar::<Fr>::new_witness(cs.clone(), || Ok(rel_r1cs.u)).unwrap();
650 let r1csVar = R1CSVar::<Fr, Fr, FpVar<Fr>>::new_witness(cs.clone(), || Ok(r1cs)).unwrap();
651
652 RelaxedR1CSGadget::check_native(r1csVar, EVar, uVar, zVar).unwrap();
653 assert!(cs.is_satisfied().unwrap());
654 }
655
656 // gets as input a circuit that implements the ConstraintSynthesizer trait, and that has been
657 // initialized.
658 fn test_relaxed_r1cs_gadget<CS: ConstraintSynthesizer<Fr>>(circuit: CS) {
659 let cs = ConstraintSystem::<Fr>::new_ref();
660
661 circuit.generate_constraints(cs.clone()).unwrap();
662 cs.finalize();
663 assert!(cs.is_satisfied().unwrap());
664
665 let cs = cs.into_inner().unwrap();
666
667 let r1cs = extract_r1cs::<Fr>(&cs);
668 let (w, x) = extract_w_x::<Fr>(&cs);
669 let z = [vec![Fr::one()], x, w].concat();
670 r1cs.check_relation(&z).unwrap();
671
672 let relaxed_r1cs = r1cs.clone().relax();
673 relaxed_r1cs.check_relation(&z).unwrap();
674
675 // set new CS for the circuit that checks the RelaxedR1CS of our original circuit
676 let cs = ConstraintSystem::<Fr>::new_ref();
677 // prepare the inputs for our circuit
678 let zVar = Vec::<FpVar<Fr>>::new_witness(cs.clone(), || Ok(z)).unwrap();
679 let EVar = Vec::<FpVar<Fr>>::new_witness(cs.clone(), || Ok(relaxed_r1cs.E)).unwrap();
680 let uVar = FpVar::<Fr>::new_witness(cs.clone(), || Ok(relaxed_r1cs.u)).unwrap();
681 let r1csVar = R1CSVar::<Fr, Fr, FpVar<Fr>>::new_witness(cs.clone(), || Ok(r1cs)).unwrap();
682
683 RelaxedR1CSGadget::check_native(r1csVar, EVar, uVar, zVar).unwrap();
684 assert!(cs.is_satisfied().unwrap());
685 }
686
687 #[test]
688 fn test_relaxed_r1cs_small_gadget_arkworks() {
689 let z_i = vec![Fr::from(3_u32)];
690 let cubic_circuit = CubicFCircuit::<Fr>::new(()).unwrap();
691 let circuit = WrapperCircuit::<Fr, CubicFCircuit<Fr>> {
692 FC: cubic_circuit,
693 z_i: Some(z_i.clone()),
694 z_i1: Some(cubic_circuit.step_native(0, z_i, vec![]).unwrap()),
695 };
696
697 test_relaxed_r1cs_gadget(circuit);
698 }
699
700 struct Sha256TestCircuit<F: PrimeField> {
701 _f: PhantomData<F>,
702 pub x: Vec<u8>,
703 pub y: Vec<u8>,
704 }
705 impl<F: PrimeField> ConstraintSynthesizer<F> for Sha256TestCircuit<F> {
706 fn generate_constraints(self, cs: ConstraintSystemRef<F>) -> Result<(), SynthesisError> {
707 let x = Vec::<UInt8<F>>::new_witness(cs.clone(), || Ok(self.x))?;
708 let y = Vec::<UInt8<F>>::new_input(cs.clone(), || Ok(self.y))?;
709
710 let unitVar = UnitVar::default();
711 let comp_y = <Sha256Gadget<F> as CRHSchemeGadget<Sha256, F>>::evaluate(&unitVar, &x)?;
712 comp_y.0.enforce_equal(&y)?;
713 Ok(())
714 }
715 }
716 #[test]
717 fn test_relaxed_r1cs_medium_gadget_arkworks() {
718 let x = Fr::from(5_u32).into_bigint().to_bytes_le();
719 let y = <Sha256 as CRHScheme>::evaluate(&(), x.clone()).unwrap();
720
721 let circuit = Sha256TestCircuit::<Fr> {
722 _f: PhantomData,
723 x,
724 y,
725 };
726 test_relaxed_r1cs_gadget(circuit);
727 }
728
729 #[test]
730 fn test_relaxed_r1cs_custom_circuit() {
731 let n_constraints = 10_000;
732 let custom_circuit = CustomFCircuit::<Fr>::new(n_constraints).unwrap();
733 let z_i = vec![Fr::from(5_u32)];
734 let circuit = WrapperCircuit::<Fr, CustomFCircuit<Fr>> {
735 FC: custom_circuit,
736 z_i: Some(z_i.clone()),
737 z_i1: Some(custom_circuit.step_native(0, z_i, vec![]).unwrap()),
738 };
739 test_relaxed_r1cs_gadget(circuit);
740 }
741
742 #[test]
743 fn test_relaxed_r1cs_nonnative_circuit() {
744 let cs = ConstraintSystem::<Fq>::new_ref();
745 // in practice we would use CycleFoldCircuit, but is a very big circuit (when computed
746 // non-natively inside the RelaxedR1CS circuit), so in order to have a short test we use a
747 // custom circuit.
748 let custom_circuit = CustomFCircuit::<Fq>::new(10).unwrap();
749 let z_i = vec![Fq::from(5_u32)];
750 let circuit = WrapperCircuit::<Fq, CustomFCircuit<Fq>> {
751 FC: custom_circuit,
752 z_i: Some(z_i.clone()),
753 z_i1: Some(custom_circuit.step_native(0, z_i, vec![]).unwrap()),
754 };
755 circuit.generate_constraints(cs.clone()).unwrap();
756 cs.finalize();
757 let cs = cs.into_inner().unwrap();
758 let r1cs = extract_r1cs::<Fq>(&cs);
759 let (w, x) = extract_w_x::<Fq>(&cs);
760 let z = [vec![Fq::one()], x, w].concat();
761
762 let relaxed_r1cs = r1cs.clone().relax();
763
764 // natively
765 let cs = ConstraintSystem::<Fq>::new_ref();
766 let zVar = Vec::<FpVar<Fq>>::new_witness(cs.clone(), || Ok(z.clone())).unwrap();
767 let EVar =
768 Vec::<FpVar<Fq>>::new_witness(cs.clone(), || Ok(relaxed_r1cs.clone().E)).unwrap();
769 let uVar = FpVar::<Fq>::new_witness(cs.clone(), || Ok(relaxed_r1cs.u)).unwrap();
770 let r1csVar =
771 R1CSVar::<Fq, Fq, FpVar<Fq>>::new_witness(cs.clone(), || Ok(r1cs.clone())).unwrap();
772 RelaxedR1CSGadget::check_native(r1csVar, EVar, uVar, zVar).unwrap();
773
774 // non-natively
775 let cs = ConstraintSystem::<Fr>::new_ref();
776 let zVar = Vec::new_witness(cs.clone(), || Ok(z)).unwrap();
777 let EVar = Vec::new_witness(cs.clone(), || Ok(relaxed_r1cs.E)).unwrap();
778 let uVar = NonNativeUintVar::<Fr>::new_witness(cs.clone(), || Ok(relaxed_r1cs.u)).unwrap();
779 let r1csVar =
780 R1CSVar::<Fq, Fr, NonNativeUintVar<Fr>>::new_witness(cs.clone(), || Ok(r1cs)).unwrap();
781 RelaxedR1CSGadget::check_nonnative(r1csVar, EVar, uVar, zVar).unwrap();
782 }
783
784 #[test]
785 fn test_decider_circuit() {
786 let mut rng = ark_std::test_rng();
787 let poseidon_config = poseidon_canonical_config::<Fr>();
788
789 let F_circuit = CubicFCircuit::<Fr>::new(()).unwrap();
790 let z_0 = vec![Fr::from(3_u32)];
791
792 type N = Nova<
793 Projective,
794 GVar,
795 Projective2,
796 GVar2,
797 CubicFCircuit<Fr>,
798 Pedersen<Projective>,
799 Pedersen<Projective2>,
800 >;
801
802 let prep_param = PreprocessorParam::<
803 Projective,
804 Projective2,
805 CubicFCircuit<Fr>,
806 Pedersen<Projective>,
807 Pedersen<Projective2>,
808 >::new(poseidon_config, F_circuit);
809 let (prover_params, verifier_params) = N::preprocess(&mut rng, &prep_param).unwrap();
810
811 // generate a Nova instance and do a step of it
812 let mut nova = N::init(
813 (prover_params, verifier_params.clone()),
814 F_circuit,
815 z_0.clone(),
816 )
817 .unwrap();
818 nova.prove_step(&mut rng, vec![]).unwrap();
819 let ivc_v = nova.clone();
820 let (running_instance, incoming_instance, cyclefold_instance) = ivc_v.instances();
821 N::verify(
822 verifier_params,
823 z_0,
824 ivc_v.z_i,
825 Fr::one(),
826 running_instance,
827 incoming_instance,
828 cyclefold_instance,
829 )
830 .unwrap();
831
832 // load the DeciderEthCircuit from the generated Nova instance
833 let decider_circuit = DeciderEthCircuit::<
834 Projective,
835 GVar,
836 Projective2,
837 GVar2,
838 Pedersen<Projective>,
839 Pedersen<Projective2>,
840 >::from_nova(nova)
841 .unwrap();
842
843 let cs = ConstraintSystem::<Fr>::new_ref();
844
845 // generate the constraints and check that are satisfied by the inputs
846 decider_circuit.generate_constraints(cs.clone()).unwrap();
847 assert!(cs.is_satisfied().unwrap());
848 }
849
850 // checks that the gadget and native implementations of the challenge computation match
851 #[test]
852 fn test_kzg_challenge_gadget() {
853 let mut rng = ark_std::test_rng();
854 let poseidon_config = poseidon_canonical_config::<Fr>();
855
856 let U_i = CommittedInstance::<Projective> {
857 cmE: Projective::rand(&mut rng),
858 u: Fr::rand(&mut rng),
859 cmW: Projective::rand(&mut rng),
860 x: vec![Fr::rand(&mut rng); 1],
861 };
862
863 // compute the challenge natively
864 let (challenge_W, challenge_E) =
865 KZGChallengesGadget::<Projective>::get_challenges_native(&poseidon_config, U_i.clone())
866 .unwrap();
867
868 let cs = ConstraintSystem::<Fr>::new_ref();
869 let U_iVar =
870 CommittedInstanceVar::<Projective>::new_witness(cs.clone(), || Ok(U_i.clone()))
871 .unwrap();
872
873 let (challenge_W_Var, challenge_E_Var) =
874 KZGChallengesGadget::<Projective>::get_challenges_gadget(
875 cs.clone(),
876 &poseidon_config,
877 U_iVar,
878 )
879 .unwrap();
880 assert!(cs.is_satisfied().unwrap());
881
882 // check that the natively computed and in-circuit computed hashes match
883 use ark_r1cs_std::R1CSVar;
884 assert_eq!(challenge_W_Var.value().unwrap(), challenge_W);
885 assert_eq!(challenge_E_Var.value().unwrap(), challenge_E);
886 }
887
888 // The test test_polynomial_interpolation is temporary disabled due
889 // https://github.com/privacy-scaling-explorations/sonobe/issues/80
890 // for n<=11 it will work, but for n>11 it will fail with stack overflow.
891 #[ignore]
892 #[test]
893 fn test_polynomial_interpolation() {
894 let mut rng = ark_std::test_rng();
895 let n = 12;
896 let l = 1 << n;
897
898 let v: Vec<Fr> = std::iter::repeat_with(|| Fr::rand(&mut rng))
899 .take(l)
900 .collect();
901 let challenge = Fr::rand(&mut rng);
902
903 use ark_poly::Polynomial;
904 let polynomial = poly_from_vec(v.to_vec()).unwrap();
905 let eval = polynomial.evaluate(&challenge);
906
907 let cs = ConstraintSystem::<Fr>::new_ref();
908 let vVar = Vec::<FpVar<Fr>>::new_witness(cs.clone(), || Ok(v)).unwrap();
909 let challengeVar = FpVar::<Fr>::new_witness(cs.clone(), || Ok(challenge)).unwrap();
910
911 let evalVar = evaluate_gadget::<Fr>(vVar, challengeVar).unwrap();
912
913 use ark_r1cs_std::R1CSVar;
914 assert_eq!(evalVar.value().unwrap(), eval);
915 assert!(cs.is_satisfied().unwrap());
916 }
917}