sonobe/folding-schemes/src/folding/circuits/cyclefold.rs
folding-schemes/src/folding/circuits/cyclefold.rsRaw
1/// Contains [CycleFold](https://eprint.iacr.org/2023/1192.pdf) related circuits and functions that
2/// are shared across the different folding schemes
3use ark_crypto_primitives::sponge::{Absorb, CryptographicSponge};
4use ark_ec::{AffineRepr, CurveGroup, Group};
5use ark_ff::{BigInteger, Field, PrimeField};
6use ark_r1cs_std::{
7 alloc::{AllocVar, AllocationMode},
8 boolean::Boolean,
9 eq::EqGadget,
10 fields::fp::FpVar,
11 groups::GroupOpsBounds,
12 prelude::CurveVar,
13 ToConstraintFieldGadget,
14};
15use ark_relations::r1cs::{
16 ConstraintSynthesizer, ConstraintSystem, ConstraintSystemRef, Namespace, SynthesisError,
17};
18use ark_std::fmt::Debug;
19use ark_std::rand::RngCore;
20use ark_std::Zero;
21use core::{borrow::Borrow, marker::PhantomData};
22
23use super::{nonnative::uint::NonNativeUintVar, CF1, CF2};
24use crate::arith::r1cs::{extract_w_x, R1CS};
25use crate::commitment::CommitmentScheme;
26use crate::constants::NOVA_N_BITS_RO;
27use crate::folding::nova::nifs::NIFS;
28use crate::transcript::{AbsorbNonNative, AbsorbNonNativeGadget, Transcript, TranscriptVar};
29use crate::Error;
30
31/// Re-export the Nova committed instance as `CycleFoldCommittedInstance` and
32/// witness as `CycleFoldWitness`, for clarity and consistency
33pub use crate::folding::nova::{
34 CommittedInstance as CycleFoldCommittedInstance, Witness as CycleFoldWitness,
35};
36
37/// CycleFoldCommittedInstanceVar is the CycleFold CommittedInstance represented
38/// in folding verifier circuit
39#[derive(Debug, Clone)]
40pub struct CycleFoldCommittedInstanceVar<C: CurveGroup, GC: CurveVar<C, CF2<C>>>
41where
42 for<'a> &'a GC: GroupOpsBounds<'a, C, GC>,
43{
44 pub cmE: GC,
45 pub u: NonNativeUintVar<CF2<C>>,
46 pub cmW: GC,
47 pub x: Vec<NonNativeUintVar<CF2<C>>>,
48}
49impl<C, GC> AllocVar<CycleFoldCommittedInstance<C>, CF2<C>> for CycleFoldCommittedInstanceVar<C, GC>
50where
51 C: CurveGroup,
52 GC: CurveVar<C, CF2<C>>,
53 <C as ark_ec::CurveGroup>::BaseField: ark_ff::PrimeField,
54 for<'a> &'a GC: GroupOpsBounds<'a, C, GC>,
55{
56 fn new_variable<T: Borrow<CycleFoldCommittedInstance<C>>>(
57 cs: impl Into<Namespace<CF2<C>>>,
58 f: impl FnOnce() -> Result<T, SynthesisError>,
59 mode: AllocationMode,
60 ) -> Result<Self, SynthesisError> {
61 f().and_then(|val| {
62 let cs = cs.into();
63
64 let cmE = GC::new_variable(cs.clone(), || Ok(val.borrow().cmE), mode)?;
65 let cmW = GC::new_variable(cs.clone(), || Ok(val.borrow().cmW), mode)?;
66 let u = NonNativeUintVar::new_variable(cs.clone(), || Ok(val.borrow().u), mode)?;
67 let x = Vec::new_variable(cs.clone(), || Ok(val.borrow().x.clone()), mode)?;
68
69 Ok(Self { cmE, u, cmW, x })
70 })
71 }
72}
73
74impl<C: CurveGroup> AbsorbNonNative<C::BaseField> for CycleFoldCommittedInstance<C>
75where
76 C::BaseField: PrimeField + Absorb,
77{
78 // Compatible with the in-circuit `CycleFoldCommittedInstanceVar::to_native_sponge_field_elements`
79 fn to_native_sponge_field_elements(&self, dest: &mut Vec<C::BaseField>) {
80 [self.u].to_native_sponge_field_elements(dest);
81 self.x.to_native_sponge_field_elements(dest);
82 let (cmE_x, cmE_y) = match self.cmE.into_affine().xy() {
83 Some((&x, &y)) => (x, y),
84 None => (C::BaseField::zero(), C::BaseField::zero()),
85 };
86 let (cmW_x, cmW_y) = match self.cmW.into_affine().xy() {
87 Some((&x, &y)) => (x, y),
88 None => (C::BaseField::zero(), C::BaseField::zero()),
89 };
90 cmE_x.to_sponge_field_elements(dest);
91 cmE_y.to_sponge_field_elements(dest);
92 cmW_x.to_sponge_field_elements(dest);
93 cmW_y.to_sponge_field_elements(dest);
94 }
95}
96
97impl<C, GC> AbsorbNonNativeGadget<C::BaseField> for CycleFoldCommittedInstanceVar<C, GC>
98where
99 C: CurveGroup,
100 GC: CurveVar<C, CF2<C>> + ToConstraintFieldGadget<CF2<C>>,
101 <C as ark_ec::CurveGroup>::BaseField: ark_ff::PrimeField + Absorb,
102 for<'a> &'a GC: GroupOpsBounds<'a, C, GC>,
103{
104 /// Extracts the underlying field elements from `CycleFoldCommittedInstanceVar`, in the order
105 /// of `u`, `x`, `cmE.x`, `cmE.y`, `cmW.x`, `cmW.y`, `cmE.is_inf || cmW.is_inf` (|| is for
106 /// concat).
107 fn to_native_sponge_field_elements(&self) -> Result<Vec<FpVar<CF2<C>>>, SynthesisError> {
108 let mut cmE_elems = self.cmE.to_constraint_field()?;
109 let mut cmW_elems = self.cmW.to_constraint_field()?;
110
111 // See `transcript/poseidon.rs: TranscriptVar::absorb_point` for details
112 // why the last element is unnecessary.
113 cmE_elems.pop();
114 cmW_elems.pop();
115
116 Ok([
117 self.u.to_native_sponge_field_elements()?,
118 self.x
119 .iter()
120 .map(|i| i.to_native_sponge_field_elements())
121 .collect::<Result<Vec<_>, _>>()?
122 .concat(),
123 cmE_elems,
124 cmW_elems,
125 ]
126 .concat())
127 }
128}
129
130impl<C: CurveGroup> CycleFoldCommittedInstance<C>
131where
132 <C as ark_ec::CurveGroup>::BaseField: ark_ff::PrimeField + Absorb,
133{
134 /// hash_cyclefold implements the committed instance hash compatible with the
135 /// in-circuit implementation `CycleFoldCommittedInstanceVar::hash`.
136 /// Returns `H(U_i)`, where `U_i` is a `CycleFoldCommittedInstance`.
137 pub fn hash_cyclefold<T: Transcript<C::BaseField>>(
138 &self,
139 sponge: &T,
140 pp_hash: C::BaseField, // public params hash
141 ) -> C::BaseField {
142 let mut sponge = sponge.clone();
143 sponge.absorb(&pp_hash);
144 sponge.absorb_nonnative(self);
145 sponge.squeeze_field_elements(1)[0]
146 }
147}
148
149impl<C, GC> CycleFoldCommittedInstanceVar<C, GC>
150where
151 C: CurveGroup,
152 GC: CurveVar<C, CF2<C>> + ToConstraintFieldGadget<CF2<C>>,
153 <C as ark_ec::CurveGroup>::BaseField: ark_ff::PrimeField + Absorb,
154 for<'a> &'a GC: GroupOpsBounds<'a, C, GC>,
155{
156 /// hash implements the committed instance hash compatible with the native
157 /// implementation `CycleFoldCommittedInstance::hash_cyclefold`.
158 /// Returns `H(U_i)`, where `U` is a `CycleFoldCommittedInstanceVar`.
159 ///
160 /// Additionally it returns the vector of the field elements from the self
161 /// parameters, so they can be reused in other gadgets without recalculating
162 /// (reconstraining) them.
163 #[allow(clippy::type_complexity)]
164 pub fn hash<S: CryptographicSponge, T: TranscriptVar<CF2<C>, S>>(
165 self,
166 sponge: &T,
167 pp_hash: FpVar<CF2<C>>, // public params hash
168 ) -> Result<(FpVar<CF2<C>>, Vec<FpVar<CF2<C>>>), SynthesisError> {
169 let mut sponge = sponge.clone();
170 let U_vec = self.to_native_sponge_field_elements()?;
171 sponge.absorb(&pp_hash)?;
172 sponge.absorb(&U_vec)?;
173 Ok((sponge.squeeze_field_elements(1)?.pop().unwrap(), U_vec))
174 }
175}
176
177/// CommittedInstanceInCycleFoldVar represents the Nova CommittedInstance in the CycleFold circuit,
178/// where the commitments to E and W (cmW and cmW) from the CommittedInstance on the E2,
179/// represented as native points, which are folded on the auxiliary curve constraints field (E2::Fr
180/// = E1::Fq).
181#[derive(Debug, Clone)]
182pub struct CommittedInstanceInCycleFoldVar<C: CurveGroup, GC: CurveVar<C, CF2<C>>>
183where
184 for<'a> &'a GC: GroupOpsBounds<'a, C, GC>,
185{
186 _c: PhantomData<C>,
187 pub cmE: GC,
188 pub cmW: GC,
189}
190
191impl<C, GC> AllocVar<CycleFoldCommittedInstance<C>, CF2<C>>
192 for CommittedInstanceInCycleFoldVar<C, GC>
193where
194 C: CurveGroup,
195 GC: CurveVar<C, CF2<C>>,
196 for<'a> &'a GC: GroupOpsBounds<'a, C, GC>,
197{
198 fn new_variable<T: Borrow<CycleFoldCommittedInstance<C>>>(
199 cs: impl Into<Namespace<CF2<C>>>,
200 f: impl FnOnce() -> Result<T, SynthesisError>,
201 mode: AllocationMode,
202 ) -> Result<Self, SynthesisError> {
203 f().and_then(|val| {
204 let cs = cs.into();
205
206 let cmE = GC::new_variable(cs.clone(), || Ok(val.borrow().cmE), mode)?;
207 let cmW = GC::new_variable(cs.clone(), || Ok(val.borrow().cmW), mode)?;
208
209 Ok(Self {
210 _c: PhantomData,
211 cmE,
212 cmW,
213 })
214 })
215 }
216}
217
218/// In-circuit representation of the Witness associated to the CommittedInstance, but with
219/// non-native representation, since it is used to represent the CycleFold witness. This struct is
220/// used in the Decider circuit.
221#[derive(Debug, Clone)]
222pub struct CycleFoldWitnessVar<C: CurveGroup> {
223 pub E: Vec<NonNativeUintVar<CF2<C>>>,
224 pub rE: NonNativeUintVar<CF2<C>>,
225 pub W: Vec<NonNativeUintVar<CF2<C>>>,
226 pub rW: NonNativeUintVar<CF2<C>>,
227}
228
229impl<C> AllocVar<CycleFoldWitness<C>, CF2<C>> for CycleFoldWitnessVar<C>
230where
231 C: CurveGroup,
232 <C as ark_ec::CurveGroup>::BaseField: PrimeField,
233{
234 fn new_variable<T: Borrow<CycleFoldWitness<C>>>(
235 cs: impl Into<Namespace<CF2<C>>>,
236 f: impl FnOnce() -> Result<T, SynthesisError>,
237 mode: AllocationMode,
238 ) -> Result<Self, SynthesisError> {
239 f().and_then(|val| {
240 let cs = cs.into();
241
242 let E = Vec::new_variable(cs.clone(), || Ok(val.borrow().E.clone()), mode)?;
243 let rE = NonNativeUintVar::new_variable(cs.clone(), || Ok(val.borrow().rE), mode)?;
244
245 let W = Vec::new_variable(cs.clone(), || Ok(val.borrow().W.clone()), mode)?;
246 let rW = NonNativeUintVar::new_variable(cs.clone(), || Ok(val.borrow().rW), mode)?;
247
248 Ok(Self { E, rE, W, rW })
249 })
250 }
251}
252
253/// This is the gadget used in the AugmentedFCircuit to verify the CycleFold instances folding,
254/// which checks the correct RLC of u,x,cmE,cmW (hence the name containing 'Full', since it checks
255/// all the RLC values, not only the native ones). It assumes that ci2.cmE=0, ci2.u=1.
256pub struct NIFSFullGadget<C: CurveGroup, GC: CurveVar<C, CF2<C>>> {
257 _c: PhantomData<C>,
258 _gc: PhantomData<GC>,
259}
260
261impl<C: CurveGroup, GC: CurveVar<C, CF2<C>>> NIFSFullGadget<C, GC>
262where
263 C: CurveGroup,
264 GC: CurveVar<C, CF2<C>>,
265 <C as ark_ec::CurveGroup>::BaseField: ark_ff::PrimeField,
266 for<'a> &'a GC: GroupOpsBounds<'a, C, GC>,
267{
268 pub fn fold_committed_instance(
269 r_bits: Vec<Boolean<CF2<C>>>,
270 cmT: GC,
271 ci1: CycleFoldCommittedInstanceVar<C, GC>,
272 // ci2 is assumed to be always with cmE=0, u=1 (checks done previous to this method)
273 ci2: CycleFoldCommittedInstanceVar<C, GC>,
274 ) -> Result<CycleFoldCommittedInstanceVar<C, GC>, SynthesisError> {
275 // r_nonnat is equal to r_bits just that in a different format
276 let r_nonnat = {
277 let mut bits = r_bits.clone();
278 bits.resize(CF1::<C>::MODULUS_BIT_SIZE as usize, Boolean::FALSE);
279 NonNativeUintVar::from(&bits)
280 };
281 Ok(CycleFoldCommittedInstanceVar {
282 cmE: cmT.scalar_mul_le(r_bits.iter())? + ci1.cmE,
283 cmW: ci1.cmW + ci2.cmW.scalar_mul_le(r_bits.iter())?,
284 u: ci1.u.add_no_align(&r_nonnat).modulo::<CF1<C>>()?,
285 x: ci1
286 .x
287 .iter()
288 .zip(ci2.x)
289 .map(|(a, b)| {
290 a.add_no_align(&r_nonnat.mul_no_align(&b)?)
291 .modulo::<CF1<C>>()
292 })
293 .collect::<Result<Vec<_>, _>>()?,
294 })
295 }
296
297 pub fn verify(
298 // assumes that r_bits is equal to r_nonnat just that in a different format
299 r_bits: Vec<Boolean<CF2<C>>>,
300 cmT: GC,
301 ci1: CycleFoldCommittedInstanceVar<C, GC>,
302 // ci2 is assumed to be always with cmE=0, u=1 (checks done previous to this method)
303 ci2: CycleFoldCommittedInstanceVar<C, GC>,
304 ci3: CycleFoldCommittedInstanceVar<C, GC>,
305 ) -> Result<(), SynthesisError> {
306 let ci = Self::fold_committed_instance(r_bits, cmT, ci1, ci2)?;
307
308 ci.cmE.enforce_equal(&ci3.cmE)?;
309 ci.u.enforce_equal_unaligned(&ci3.u)?;
310 ci.cmW.enforce_equal(&ci3.cmW)?;
311 for (x, y) in ci.x.iter().zip(ci3.x.iter()) {
312 x.enforce_equal_unaligned(y)?;
313 }
314
315 Ok(())
316 }
317}
318
319/// CycleFoldChallengeGadget computes the RO challenge used for the CycleFold instances NIFS, it contains a
320/// rust-native and a in-circuit compatible versions.
321pub struct CycleFoldChallengeGadget<C: CurveGroup, GC: CurveVar<C, CF2<C>>> {
322 _c: PhantomData<C>, // Nova's Curve2, the one used for the CycleFold circuit
323 _gc: PhantomData<GC>,
324}
325impl<C, GC> CycleFoldChallengeGadget<C, GC>
326where
327 C: CurveGroup,
328 GC: CurveVar<C, CF2<C>> + ToConstraintFieldGadget<CF2<C>>,
329 <C as CurveGroup>::BaseField: PrimeField,
330 <C as CurveGroup>::BaseField: Absorb,
331 for<'a> &'a GC: GroupOpsBounds<'a, C, GC>,
332{
333 pub fn get_challenge_native<T: Transcript<C::BaseField>>(
334 transcript: &mut T,
335 pp_hash: C::BaseField, // public params hash
336 U_i: CycleFoldCommittedInstance<C>,
337 u_i: CycleFoldCommittedInstance<C>,
338 cmT: C,
339 ) -> Vec<bool> {
340 transcript.absorb(&pp_hash);
341 transcript.absorb_nonnative(&U_i);
342 transcript.absorb_nonnative(&u_i);
343 transcript.absorb_point(&cmT);
344 transcript.squeeze_bits(NOVA_N_BITS_RO)
345 }
346
347 // compatible with the native get_challenge_native
348 pub fn get_challenge_gadget<S: CryptographicSponge, T: TranscriptVar<C::BaseField, S>>(
349 transcript: &mut T,
350 pp_hash: FpVar<C::BaseField>, // public params hash
351 U_i_vec: Vec<FpVar<C::BaseField>>,
352 u_i: CycleFoldCommittedInstanceVar<C, GC>,
353 cmT: GC,
354 ) -> Result<Vec<Boolean<C::BaseField>>, SynthesisError> {
355 transcript.absorb(&pp_hash)?;
356 transcript.absorb(&U_i_vec)?;
357 transcript.absorb_nonnative(&u_i)?;
358 transcript.absorb_point(&cmT)?;
359 transcript.squeeze_bits(NOVA_N_BITS_RO)
360 }
361}
362
363pub trait CycleFoldConfig {
364 /// `N_INPUT_POINTS` specifies the number of input points that are folded in
365 /// [`CycleFoldCircuit`] via random linear combinations.
366 const N_INPUT_POINTS: usize;
367 /// `RANDOMNESS_BIT_LENGTH` is the (maximum) bit length of randomness `r`.
368 const RANDOMNESS_BIT_LENGTH: usize;
369 /// `FIELD_CAPACITY` is the maximum number of bits that can be stored in a
370 /// field element.
371 ///
372 /// E.g., given a randomness `r` with `RANDOMNESS_BIT_LENGTH` bits, we need
373 /// `RANDOMNESS_BIT_LENGTH / FIELD_CAPACITY` field elements to represent `r`
374 /// compactly in-circuit.
375 const FIELD_CAPACITY: usize = CF2::<Self::C>::MODULUS_BIT_SIZE as usize - 1;
376
377 /// Public inputs length for the CycleFoldCircuit.
378 /// * For Nova this is: `|[r, p1.x,y, p2.x,y, p3.x,y]|`
379 /// * In general, `|[r, (p_i.x,y)*n_points, p_folded.x,y]|`.
380 ///
381 /// Thus, `IO_LEN` is:
382 /// `RANDOMNESS_BIT_LENGTH / FIELD_CAPACITY + 2 * N_INPUT_POINTS + 2`
383 const IO_LEN: usize = {
384 Self::RANDOMNESS_BIT_LENGTH.div_ceil(Self::FIELD_CAPACITY) + 2 * Self::N_INPUT_POINTS + 2
385 };
386
387 type F: Field;
388 type C: CurveGroup<BaseField = Self::F>;
389}
390
391/// CycleFoldCircuit contains the constraints that check the correct fold of the committed
392/// instances from Curve1. Namely, it checks the random linear combinations of the elliptic curve
393/// (Curve1) points of u_i, U_i leading to U_{i+1}
394#[derive(Debug, Clone)]
395pub struct CycleFoldCircuit<CFG: CycleFoldConfig, GC: CurveVar<CFG::C, CFG::F>> {
396 pub _gc: PhantomData<GC>,
397 /// r_bits is the bit representation of the r whose powers are used in the
398 /// random-linear-combination inside the CycleFoldCircuit
399 pub r_bits: Option<Vec<bool>>,
400 /// points to be folded in the CycleFoldCircuit
401 pub points: Option<Vec<CFG::C>>,
402 /// public inputs (cf_u_{i+1}.x)
403 pub x: Option<Vec<CFG::F>>,
404}
405
406impl<CFG: CycleFoldConfig, GC: CurveVar<CFG::C, CFG::F>> CycleFoldCircuit<CFG, GC> {
407 /// n_points indicates the number of points being folded in the CycleFoldCircuit
408 pub fn empty() -> Self {
409 Self {
410 _gc: PhantomData,
411 r_bits: None,
412 points: None,
413 x: None,
414 }
415 }
416}
417
418impl<CFG: CycleFoldConfig, GC: CurveVar<CFG::C, CFG::F>> ConstraintSynthesizer<CFG::F>
419 for CycleFoldCircuit<CFG, GC>
420where
421 GC: ToConstraintFieldGadget<CFG::F>,
422 CFG::F: PrimeField,
423 for<'a> &'a GC: GroupOpsBounds<'a, CFG::C, GC>,
424{
425 fn generate_constraints(self, cs: ConstraintSystemRef<CFG::F>) -> Result<(), SynthesisError> {
426 let r_bits = Vec::<Boolean<CFG::F>>::new_witness(cs.clone(), || {
427 Ok(self
428 .r_bits
429 .unwrap_or(vec![false; CFG::RANDOMNESS_BIT_LENGTH]))
430 })?;
431 let points = Vec::<GC>::new_witness(cs.clone(), || {
432 Ok(self
433 .points
434 .unwrap_or(vec![CFG::C::zero(); CFG::N_INPUT_POINTS]))
435 })?;
436
437 #[cfg(test)]
438 {
439 assert_eq!(CFG::N_INPUT_POINTS, points.len());
440 assert_eq!(CFG::RANDOMNESS_BIT_LENGTH, r_bits.len());
441 }
442
443 // Fold the original points of the instances natively in CycleFold.
444 // In Nova,
445 // - for the cmW we're computing: U_i1.cmW = U_i.cmW + r * u_i.cmW
446 // - for the cmE we're computing: U_i1.cmE = U_i.cmE + r * cmT + r^2 * u_i.cmE, where u_i.cmE
447 // is assumed to be 0, so, U_i1.cmE = U_i.cmE + r * cmT
448 // We want to compute
449 // P_folded = p_0 + r * P_1 + r^2 * P_2 + r^3 * P_3 + ... + r^{n-2} * P_{n-2} + r^{n-1} * P_{n-1}
450 // so in order to do it more efficiently (less constraints) we do
451 // P_folded = (((P_{n-1} * r + P_{n-2}) * r + P_{n-3})... ) * r + P_0
452 let mut p_folded: GC = points[CFG::N_INPUT_POINTS - 1].clone();
453 for i in (0..CFG::N_INPUT_POINTS - 1).rev() {
454 p_folded = p_folded.scalar_mul_le(r_bits.iter())? + points[i].clone();
455 }
456
457 let x = Vec::<FpVar<CFG::F>>::new_input(cs.clone(), || {
458 Ok(self.x.unwrap_or(vec![CFG::F::zero(); CFG::IO_LEN]))
459 })?;
460 #[cfg(test)]
461 assert_eq!(x.len(), CFG::IO_LEN); // non-constrained sanity check
462
463 // Check that the points coordinates are placed as the public input x:
464 // In Nova, this is: x == [r, p1, p2, p3] (wheere p3 is the p_folded).
465 // In multifolding schemes such as HyperNova, this is:
466 // computed_x = [r, p_0, p_1, p_2, ..., p_n, p_folded],
467 // where each p_i is in fact p_i.to_constraint_field()
468 let r_fp = Boolean::le_bits_to_fp_var(&r_bits)?;
469 let points_aux: Vec<FpVar<CFG::F>> = points
470 .iter()
471 .map(|p_i| Ok(p_i.to_constraint_field()?[..2].to_vec()))
472 .collect::<Result<Vec<_>, SynthesisError>>()?
473 .into_iter()
474 .flatten()
475 .collect();
476
477 let computed_x: Vec<FpVar<CFG::F>> = [
478 vec![r_fp],
479 points_aux,
480 p_folded.to_constraint_field()?[..2].to_vec(),
481 ]
482 .concat();
483 computed_x.enforce_equal(&x)?;
484
485 Ok(())
486 }
487}
488
489/// Folds the given cyclefold circuit and its instances. This method is abstracted from any folding
490/// scheme struct because it is used both by Nova & HyperNova's CycleFold.
491#[allow(clippy::type_complexity)]
492#[allow(clippy::too_many_arguments)]
493pub fn fold_cyclefold_circuit<CFG, C1, GC1, C2, GC2, CS2, const H: bool>(
494 transcript: &mut impl Transcript<C1::ScalarField>,
495 cf_r1cs: R1CS<C2::ScalarField>,
496 cf_cs_params: CS2::ProverParams,
497 pp_hash: C1::ScalarField, // public params hash
498 cf_W_i: CycleFoldWitness<C2>, // witness of the running instance
499 cf_U_i: CycleFoldCommittedInstance<C2>, // running instance
500 cf_u_i_x: Vec<C2::ScalarField>,
501 cf_circuit: CycleFoldCircuit<CFG, GC1>,
502 mut rng: impl RngCore,
503) -> Result<
504 (
505 CycleFoldWitness<C2>,
506 CycleFoldCommittedInstance<C2>, // u_i
507 CycleFoldWitness<C2>, // W_i1
508 CycleFoldCommittedInstance<C2>, // U_i1
509 C2, // cmT
510 C2::ScalarField, // r_Fq
511 ),
512 Error,
513>
514where
515 CFG: CycleFoldConfig<C = C1, F = CF2<C1>>,
516 C1: CurveGroup,
517 GC1: CurveVar<C1, CF2<C1>> + ToConstraintFieldGadget<CF2<C1>>,
518 C2: CurveGroup,
519 GC2: CurveVar<C2, CF2<C2>> + ToConstraintFieldGadget<CF2<C2>>,
520 CS2: CommitmentScheme<C2, H>,
521 <C1 as CurveGroup>::BaseField: PrimeField,
522 <C2 as CurveGroup>::BaseField: PrimeField,
523 <C1 as Group>::ScalarField: Absorb,
524 <C2 as Group>::ScalarField: Absorb,
525 C1: CurveGroup<BaseField = C2::ScalarField, ScalarField = C2::BaseField>,
526 for<'a> &'a GC1: GroupOpsBounds<'a, C1, GC1>,
527 for<'a> &'a GC2: GroupOpsBounds<'a, C2, GC2>,
528{
529 let cs2 = ConstraintSystem::<C1::BaseField>::new_ref();
530 cf_circuit.generate_constraints(cs2.clone())?;
531
532 let cs2 = cs2.into_inner().ok_or(Error::NoInnerConstraintSystem)?;
533 let (cf_w_i, cf_x_i) = extract_w_x::<C1::BaseField>(&cs2);
534 if cf_x_i != cf_u_i_x {
535 return Err(Error::NotEqual);
536 }
537
538 #[cfg(test)]
539 assert_eq!(cf_x_i.len(), CFG::IO_LEN);
540
541 // fold cyclefold instances
542 let cf_w_i = CycleFoldWitness::<C2>::new::<H>(cf_w_i.clone(), cf_r1cs.A.n_rows, &mut rng);
543 let cf_u_i: CycleFoldCommittedInstance<C2> =
544 cf_w_i.commit::<CS2, H>(&cf_cs_params, cf_x_i.clone())?;
545
546 // compute T* and cmT* for CycleFoldCircuit
547 let (cf_T, cf_cmT) = NIFS::<C2, CS2, H>::compute_cyclefold_cmT(
548 &cf_cs_params,
549 &cf_r1cs,
550 &cf_w_i,
551 &cf_u_i,
552 &cf_W_i,
553 &cf_U_i,
554 )?;
555
556 let cf_r_bits = CycleFoldChallengeGadget::<C2, GC2>::get_challenge_native(
557 transcript,
558 pp_hash,
559 cf_U_i.clone(),
560 cf_u_i.clone(),
561 cf_cmT,
562 );
563 let cf_r_Fq = C1::BaseField::from_bigint(BigInteger::from_bits_le(&cf_r_bits))
564 .expect("cf_r_bits out of bounds");
565
566 let (cf_W_i1, cf_U_i1) = NIFS::<C2, CS2, H>::fold_instances(
567 cf_r_Fq, &cf_W_i, &cf_U_i, &cf_w_i, &cf_u_i, &cf_T, cf_cmT,
568 )?;
569 Ok((cf_w_i, cf_u_i, cf_W_i1, cf_U_i1, cf_cmT, cf_r_Fq))
570}
571
572#[cfg(test)]
573pub mod tests {
574 use ark_bn254::{constraints::GVar, Fq, Fr, G1Projective as Projective};
575 use ark_crypto_primitives::sponge::{
576 constraints::CryptographicSpongeVar,
577 poseidon::{constraints::PoseidonSpongeVar, PoseidonSponge},
578 };
579 use ark_r1cs_std::R1CSVar;
580 use ark_std::UniformRand;
581
582 use super::*;
583 use crate::folding::nova::nifs::tests::prepare_simple_fold_inputs;
584 use crate::transcript::poseidon::poseidon_canonical_config;
585 use crate::utils::get_cm_coordinates;
586
587 struct TestCycleFoldConfig<C: CurveGroup, const N: usize> {
588 _c: PhantomData<C>,
589 }
590
591 impl<C: CurveGroup, const N: usize> CycleFoldConfig for TestCycleFoldConfig<C, N> {
592 const RANDOMNESS_BIT_LENGTH: usize = NOVA_N_BITS_RO;
593 const N_INPUT_POINTS: usize = N;
594 type C = C;
595 type F = C::BaseField;
596 }
597
598 #[test]
599 fn test_committed_instance_cyclefold_var() {
600 let mut rng = ark_std::test_rng();
601
602 let ci = CycleFoldCommittedInstance::<Projective> {
603 cmE: Projective::rand(&mut rng),
604 u: Fr::rand(&mut rng),
605 cmW: Projective::rand(&mut rng),
606 x: vec![Fr::rand(&mut rng); 1],
607 };
608
609 // check the instantiation of the CycleFold side:
610 let cs = ConstraintSystem::<Fq>::new_ref();
611 let ciVar =
612 CommittedInstanceInCycleFoldVar::<Projective, GVar>::new_witness(cs.clone(), || {
613 Ok(ci.clone())
614 })
615 .unwrap();
616 assert_eq!(ciVar.cmE.value().unwrap(), ci.cmE);
617 assert_eq!(ciVar.cmW.value().unwrap(), ci.cmW);
618 }
619
620 #[test]
621 fn test_CycleFoldCircuit_n_points_constraints() {
622 const n: usize = 16;
623 let mut rng = ark_std::test_rng();
624
625 // points to random-linear-combine
626 let points: Vec<Projective> = std::iter::repeat_with(|| Projective::rand(&mut rng))
627 .take(n)
628 .collect();
629
630 use std::ops::Mul;
631 let rho_raw = Fq::rand(&mut rng);
632 let rho_bits = rho_raw.into_bigint().to_bits_le()[..NOVA_N_BITS_RO].to_vec();
633 let rho_Fq = Fq::from_bigint(BigInteger::from_bits_le(&rho_bits)).unwrap();
634 let rho_Fr = Fr::from_bigint(BigInteger::from_bits_le(&rho_bits)).unwrap();
635 let mut res = Projective::zero();
636 use ark_std::One;
637 let mut rho_i = Fr::one();
638 for point_i in points.iter() {
639 res += point_i.mul(rho_i);
640 rho_i *= rho_Fr;
641 }
642
643 // cs is the Constraint System on the Curve Cycle auxiliary curve constraints field
644 // (E1::Fq=E2::Fr)
645 let cs = ConstraintSystem::<Fq>::new_ref();
646
647 let x: Vec<Fq> = [
648 vec![rho_Fq],
649 points.iter().flat_map(get_cm_coordinates).collect(),
650 get_cm_coordinates(&res),
651 ]
652 .concat();
653 let cf_circuit = CycleFoldCircuit::<TestCycleFoldConfig<Projective, n>, GVar> {
654 _gc: PhantomData,
655 r_bits: Some(rho_bits),
656 points: Some(points),
657 x: Some(x.clone()),
658 };
659 cf_circuit.generate_constraints(cs.clone()).unwrap();
660 assert!(cs.is_satisfied().unwrap());
661 }
662
663 #[test]
664 fn test_nifs_full_gadget() {
665 let (_, _, _, _, ci1, _, ci2, _, ci3, _, cmT, r_bits, _) = prepare_simple_fold_inputs();
666
667 let cs = ConstraintSystem::<Fq>::new_ref();
668
669 let r_bitsVar = Vec::<Boolean<Fq>>::new_witness(cs.clone(), || Ok(r_bits)).unwrap();
670
671 let ci1Var =
672 CycleFoldCommittedInstanceVar::<Projective, GVar>::new_witness(cs.clone(), || {
673 Ok(ci1.clone())
674 })
675 .unwrap();
676 let ci2Var =
677 CycleFoldCommittedInstanceVar::<Projective, GVar>::new_witness(cs.clone(), || {
678 Ok(ci2.clone())
679 })
680 .unwrap();
681 let ci3Var =
682 CycleFoldCommittedInstanceVar::<Projective, GVar>::new_witness(cs.clone(), || {
683 Ok(ci3.clone())
684 })
685 .unwrap();
686 let cmTVar = GVar::new_witness(cs.clone(), || Ok(cmT)).unwrap();
687
688 NIFSFullGadget::<Projective, GVar>::verify(r_bitsVar, cmTVar, ci1Var, ci2Var, ci3Var)
689 .unwrap();
690 assert!(cs.is_satisfied().unwrap());
691 }
692
693 #[test]
694 fn test_cyclefold_challenge_gadget() {
695 let mut rng = ark_std::test_rng();
696 let poseidon_config = poseidon_canonical_config::<Fq>();
697 let mut transcript = PoseidonSponge::<Fq>::new(&poseidon_config);
698
699 let u_i = CycleFoldCommittedInstance::<Projective> {
700 cmE: Projective::zero(), // zero on purpose, so we test also the zero point case
701 u: Fr::zero(),
702 cmW: Projective::rand(&mut rng),
703 x: std::iter::repeat_with(|| Fr::rand(&mut rng))
704 .take(TestCycleFoldConfig::<Projective, 2>::IO_LEN)
705 .collect(),
706 };
707 let U_i = CycleFoldCommittedInstance::<Projective> {
708 cmE: Projective::rand(&mut rng),
709 u: Fr::rand(&mut rng),
710 cmW: Projective::rand(&mut rng),
711 x: std::iter::repeat_with(|| Fr::rand(&mut rng))
712 .take(TestCycleFoldConfig::<Projective, 2>::IO_LEN)
713 .collect(),
714 };
715 let cmT = Projective::rand(&mut rng);
716
717 // compute the challenge natively
718 let pp_hash = Fq::from(42u32); // only for test
719 let r_bits = CycleFoldChallengeGadget::<Projective, GVar>::get_challenge_native(
720 &mut transcript,
721 pp_hash,
722 U_i.clone(),
723 u_i.clone(),
724 cmT,
725 );
726
727 let cs = ConstraintSystem::<Fq>::new_ref();
728 let u_iVar =
729 CycleFoldCommittedInstanceVar::<Projective, GVar>::new_witness(cs.clone(), || {
730 Ok(u_i.clone())
731 })
732 .unwrap();
733 let U_iVar =
734 CycleFoldCommittedInstanceVar::<Projective, GVar>::new_witness(cs.clone(), || {
735 Ok(U_i.clone())
736 })
737 .unwrap();
738 let cmTVar = GVar::new_witness(cs.clone(), || Ok(cmT)).unwrap();
739 let mut transcript_var =
740 PoseidonSpongeVar::<Fq>::new(ConstraintSystem::<Fq>::new_ref(), &poseidon_config);
741
742 let pp_hashVar = FpVar::<Fq>::new_witness(cs.clone(), || Ok(pp_hash)).unwrap();
743 let r_bitsVar = CycleFoldChallengeGadget::<Projective, GVar>::get_challenge_gadget(
744 &mut transcript_var,
745 pp_hashVar,
746 U_iVar.to_native_sponge_field_elements().unwrap(),
747 u_iVar,
748 cmTVar,
749 )
750 .unwrap();
751 assert!(cs.is_satisfied().unwrap());
752
753 // check that the natively computed and in-circuit computed hashes match
754 let rVar = Boolean::le_bits_to_fp_var(&r_bitsVar).unwrap();
755 let r = Fq::from_bigint(BigInteger::from_bits_le(&r_bits)).unwrap();
756 assert_eq!(rVar.value().unwrap(), r);
757 assert_eq!(r_bitsVar.value().unwrap(), r_bits);
758 }
759
760 #[test]
761 fn test_cyclefold_hash_gadget() {
762 let mut rng = ark_std::test_rng();
763 let poseidon_config = poseidon_canonical_config::<Fq>();
764 let sponge = PoseidonSponge::<Fq>::new(&poseidon_config);
765
766 let U_i = CycleFoldCommittedInstance::<Projective> {
767 cmE: Projective::rand(&mut rng),
768 u: Fr::rand(&mut rng),
769 cmW: Projective::rand(&mut rng),
770 x: std::iter::repeat_with(|| Fr::rand(&mut rng))
771 .take(TestCycleFoldConfig::<Projective, 2>::IO_LEN)
772 .collect(),
773 };
774 let pp_hash = Fq::from(42u32); // only for test
775 let h = U_i.hash_cyclefold(&sponge, pp_hash);
776
777 let cs = ConstraintSystem::<Fq>::new_ref();
778 let U_iVar =
779 CycleFoldCommittedInstanceVar::<Projective, GVar>::new_witness(cs.clone(), || {
780 Ok(U_i.clone())
781 })
782 .unwrap();
783 let pp_hashVar = FpVar::<Fq>::new_witness(cs.clone(), || Ok(pp_hash)).unwrap();
784 let (hVar, _) = U_iVar
785 .hash(
786 &PoseidonSpongeVar::new(cs.clone(), &poseidon_config),
787 pp_hashVar,
788 )
789 .unwrap();
790 hVar.enforce_equal(&FpVar::new_witness(cs.clone(), || Ok(h)).unwrap())
791 .unwrap();
792 assert!(cs.is_satisfied().unwrap());
793 }
794}