1use crate::{
25 fft::{DensePolynomial, Polynomial},
26 msm::VariableBase,
27 polycommit::PCError,
28};
29use snarkvm_curves::traits::{AffineCurve, PairingCurve, PairingEngine, ProjectiveCurve};
30use snarkvm_fields::{One, PrimeField, Zero};
31use snarkvm_utilities::{BitIteratorBE, cfg_iter, cfg_iter_mut, rand::Uniform};
32
33use anyhow::{Result, anyhow, ensure};
34use core::{marker::PhantomData, ops::Mul};
35use itertools::Itertools;
36use rand::Rng;
37
38#[cfg(not(feature = "serial"))]
39use rayon::prelude::*;
40
41mod data_structures;
42pub use data_structures::*;
43
44use super::sonic_pc::LabeledPolynomialWithBasis;
45
46#[derive(Debug, PartialEq, Eq)]
47pub enum KZGDegreeBounds {
48 All,
49 Varuna,
50 List(Vec<usize>),
51 None,
52}
53
54impl KZGDegreeBounds {
55 pub fn get_list<F: PrimeField>(&self, max_degree: usize) -> Vec<usize> {
56 match self {
57 KZGDegreeBounds::All => (0..max_degree).collect(),
58 KZGDegreeBounds::Varuna => {
59 let mut radix_2_possible_domain_sizes = vec![];
67
68 let mut cur = 2usize;
69 while cur - 2 <= max_degree {
70 radix_2_possible_domain_sizes.push(cur - 2);
71 cur *= 2;
72 }
73
74 radix_2_possible_domain_sizes
75 }
76 KZGDegreeBounds::List(v) => v.clone(),
77 KZGDegreeBounds::None => vec![],
78 }
79 }
80}
81
82#[derive(Clone, Debug)]
87pub struct KZG10<E: PairingEngine>(PhantomData<E>);
88
89impl<E: PairingEngine> KZG10<E> {
90 pub fn load_srs(max_degree: usize) -> Result<UniversalParams<E>, PCError> {
93 let params = UniversalParams::load()?;
94 params.download_powers_for(0..(max_degree + 1))?;
95 Ok(params)
96 }
97
98 pub fn commit(
100 powers: &Powers<E>,
101 polynomial: &Polynomial<'_, E::Fr>,
102 hiding_bound: Option<usize>,
103 rng: Option<&mut dyn Rng>,
104 ) -> Result<(KZGCommitment<E>, KZGRandomness<E>), PCError> {
105 Self::check_degree_is_too_large(polynomial.degree(), powers.size())?;
106
107 let commit_time = start_timer!(|| format!(
108 "Committing to polynomial of degree {} with hiding_bound: {:?}",
109 polynomial.degree(),
110 hiding_bound,
111 ));
112
113 let mut commitment = match polynomial {
114 Polynomial::Dense(polynomial) => {
115 let (num_leading_zeros, plain_coeffs) = skip_leading_zeros_and_convert_to_bigints(polynomial);
116
117 let bases = &powers.powers_of_beta_g[num_leading_zeros..(num_leading_zeros + plain_coeffs.len())];
118
119 let msm_time = start_timer!(|| "MSM to compute commitment to plaintext poly");
120 let commitment = VariableBase::msm(bases, &plain_coeffs);
121 end_timer!(msm_time);
122
123 commitment
124 }
125 Polynomial::Sparse(polynomial) => polynomial
126 .coeffs()
127 .map(|(i, coeff)| {
128 powers.powers_of_beta_g[*i].mul_bits(BitIteratorBE::new_without_leading_zeros(coeff.to_bigint()))
129 })
130 .sum(),
131 };
132
133 let mut randomness = KZGRandomness::empty();
134 if let Some(hiding_degree) = hiding_bound {
135 let mut rng = rng.ok_or(PCError::MissingRng)?;
136 let sample_random_poly_time =
137 start_timer!(|| format!("Sampling a random polynomial of degree {hiding_degree}"));
138
139 randomness = KZGRandomness::rand(hiding_degree, false, &mut rng);
140 Self::check_hiding_bound(
141 randomness.blinding_polynomial.degree(),
142 powers.powers_of_beta_times_gamma_g.len(),
143 )?;
144 end_timer!(sample_random_poly_time);
145 }
146
147 let random_ints = convert_to_bigints(&randomness.blinding_polynomial.coeffs);
148 let msm_time = start_timer!(|| "MSM to compute commitment to random poly");
149 let random_commitment =
150 VariableBase::msm(&powers.powers_of_beta_times_gamma_g, random_ints.as_slice()).to_affine();
151 end_timer!(msm_time);
152
153 commitment.add_assign_mixed(&random_commitment);
154
155 end_timer!(commit_time);
156 Ok((KZGCommitment(commitment.into()), randomness))
157 }
158
159 pub fn commit_lagrange(
161 lagrange_basis: &LagrangeBasis<E>,
162 evaluations: &[E::Fr],
163 hiding_bound: Option<usize>,
164 rng: Option<&mut dyn Rng>,
165 ) -> Result<(KZGCommitment<E>, KZGRandomness<E>), PCError> {
166 Self::check_degree_is_too_large(evaluations.len() - 1, lagrange_basis.size())?;
167 assert_eq!(
168 evaluations.len().checked_next_power_of_two().ok_or(PCError::LagrangeBasisSizeIsTooLarge)?,
169 lagrange_basis.size()
170 );
171
172 let commit_time = start_timer!(|| format!(
173 "Committing to polynomial of degree {} with hiding_bound: {:?}",
174 evaluations.len() - 1,
175 hiding_bound,
176 ));
177
178 let evaluations = evaluations.iter().map(|e| e.to_bigint()).collect::<Vec<_>>();
179 let msm_time = start_timer!(|| "MSM to compute commitment to plaintext poly");
180 let mut commitment = VariableBase::msm(&lagrange_basis.lagrange_basis_at_beta_g, &evaluations);
181 end_timer!(msm_time);
182
183 let mut randomness = KZGRandomness::empty();
184 if let Some(hiding_degree) = hiding_bound {
185 let mut rng = rng.ok_or(PCError::MissingRng)?;
186 let sample_random_poly_time =
187 start_timer!(|| format!("Sampling a random polynomial of degree {hiding_degree}"));
188
189 randomness = KZGRandomness::rand(hiding_degree, false, &mut rng);
190 Self::check_hiding_bound(
191 randomness.blinding_polynomial.degree(),
192 lagrange_basis.powers_of_beta_times_gamma_g.len(),
193 )?;
194 end_timer!(sample_random_poly_time);
195 }
196
197 let random_ints = convert_to_bigints(&randomness.blinding_polynomial.coeffs);
198 let msm_time = start_timer!(|| "MSM to compute commitment to random poly");
199 let random_commitment =
200 VariableBase::msm(&lagrange_basis.powers_of_beta_times_gamma_g, random_ints.as_slice()).to_affine();
201 end_timer!(msm_time);
202
203 commitment.add_assign_mixed(&random_commitment);
204
205 end_timer!(commit_time);
206 Ok((KZGCommitment(commitment.into()), randomness))
207 }
208
209 pub fn compute_witness_polynomial(
216 polynomial: &DensePolynomial<E::Fr>,
217 point: E::Fr,
218 randomness: &KZGRandomness<E>,
219 ) -> Result<(DensePolynomial<E::Fr>, Option<DensePolynomial<E::Fr>>), PCError> {
220 let witness_time = start_timer!(|| "Computing witness polynomial");
221 let (witness_polynomial, _) = polynomial.divide_by_monic_linear(point);
222 end_timer!(witness_time);
223
224 let random_witness_polynomial = if randomness.is_hiding() {
225 let random_p = &randomness.blinding_polynomial;
226
227 let witness_time = start_timer!(|| "Computing random witness polynomial");
228 let (random_witness_polynomial, _) = random_p.divide_by_monic_linear(point);
229 end_timer!(witness_time);
230 Some(random_witness_polynomial)
231 } else {
232 None
233 };
234
235 Ok((witness_polynomial, random_witness_polynomial))
236 }
237
238 pub(crate) fn open_with_witness_polynomial(
239 powers: &Powers<E>,
240 point: E::Fr,
241 randomness: &KZGRandomness<E>,
242 witness_polynomial: &DensePolynomial<E::Fr>,
243 hiding_witness_polynomial: Option<&DensePolynomial<E::Fr>>,
244 ) -> Result<KZGProof<E>, PCError> {
245 Self::check_degree_is_too_large(witness_polynomial.degree(), powers.size())?;
246 let (num_leading_zeros, witness_coeffs) = skip_leading_zeros_and_convert_to_bigints(witness_polynomial);
247
248 let bases = &powers.powers_of_beta_g[num_leading_zeros..(num_leading_zeros + witness_coeffs.len())];
249
250 let witness_comm_time = start_timer!(|| "Computing commitment to witness polynomial");
251 let mut w = VariableBase::msm(bases, &witness_coeffs);
252 end_timer!(witness_comm_time);
253
254 let random_v = if let Some(hiding_witness_polynomial) = hiding_witness_polynomial {
255 let blinding_p = &randomness.blinding_polynomial;
256 let blinding_eval_time = start_timer!(|| "Evaluating random polynomial");
257 let blinding_evaluation = blinding_p.evaluate(point);
258 end_timer!(blinding_eval_time);
259
260 let random_witness_coeffs = convert_to_bigints(&hiding_witness_polynomial.coeffs);
261 let witness_comm_time = start_timer!(|| "Computing commitment to random witness polynomial");
262 w += &VariableBase::msm(&powers.powers_of_beta_times_gamma_g, &random_witness_coeffs);
263 end_timer!(witness_comm_time);
264 Some(blinding_evaluation)
265 } else {
266 None
267 };
268
269 Ok(KZGProof { w: w.to_affine(), random_v })
270 }
271
272 pub fn open_lagrange(
275 lagrange_basis: &LagrangeBasis<E>,
276 domain_elements: &[E::Fr],
277 evaluations: &[E::Fr],
278 point: E::Fr,
279 evaluation_at_point: E::Fr,
280 ) -> Result<KZGProof<E>> {
281 Self::check_degree_is_too_large(evaluations.len() - 1, lagrange_basis.size())?;
282 if lagrange_basis.domain.evaluate_vanishing_polynomial(point).is_zero() {
284 Err(anyhow!("Point cannot be in the domain"))?;
285 }
286 if evaluations.len().checked_next_power_of_two().ok_or_else(|| anyhow!("Evaluations length is too large"))?
287 != lagrange_basis.size()
288 {
289 Err(anyhow!("`evaluations.len()` must equal `domain.size()`"))?;
290 }
291
292 let mut divisor_evals = cfg_iter!(domain_elements).map(|&e| e - point).collect::<Vec<_>>();
293 snarkvm_fields::batch_inversion(&mut divisor_evals);
294 ensure!(divisor_evals.len() == evaluations.len());
295 cfg_iter_mut!(divisor_evals).zip_eq(evaluations).for_each(|(divisor_eval, &eval)| {
296 *divisor_eval *= eval - evaluation_at_point;
297 });
298 let (witness_comm, _) = Self::commit_lagrange(lagrange_basis, &divisor_evals, None, None)?;
299
300 Ok(KZGProof { w: witness_comm.0, random_v: None })
301 }
302
303 pub fn open(
306 powers: &Powers<E>,
307 polynomial: &DensePolynomial<E::Fr>,
308 point: E::Fr,
309 rand: &KZGRandomness<E>,
310 ) -> Result<KZGProof<E>, PCError> {
311 Self::check_degree_is_too_large(polynomial.degree(), powers.size())?;
312 let open_time = start_timer!(|| format!("Opening polynomial of degree {}", polynomial.degree()));
313
314 let witness_time = start_timer!(|| "Computing witness polynomials");
315 let (witness_poly, hiding_witness_poly) = Self::compute_witness_polynomial(polynomial, point, rand)?;
316 end_timer!(witness_time);
317
318 let proof =
319 Self::open_with_witness_polynomial(powers, point, rand, &witness_poly, hiding_witness_poly.as_ref());
320
321 end_timer!(open_time);
322 proof
323 }
324
325 pub fn check(
328 vk: &VerifierKey<E>,
329 commitment: &KZGCommitment<E>,
330 point: E::Fr,
331 value: E::Fr,
332 proof: &KZGProof<E>,
333 ) -> Result<bool, PCError> {
334 let check_time = start_timer!(|| "Checking evaluation");
335 let mut inner = commitment.0.to_projective() - vk.g.to_projective().mul(value);
336 if let Some(random_v) = proof.random_v {
337 inner -= &vk.gamma_g.mul(random_v);
338 }
339 let lhs = E::pairing(inner, vk.h);
340
341 let inner = vk.beta_h.to_projective() - vk.h.mul(point);
342 let rhs = E::pairing(proof.w, inner);
343
344 end_timer!(check_time, || format!("Result: {}", lhs == rhs));
345 Ok(lhs == rhs)
346 }
347
348 pub fn batch_check<R: Rng>(
351 vk: &VerifierKey<E>,
352 commitments: &[KZGCommitment<E>],
353 points: &[E::Fr],
354 values: &[E::Fr],
355 proofs: &[KZGProof<E>],
356 rng: &mut R,
357 ) -> Result<bool> {
358 let check_time = start_timer!(|| format!("Checking {} evaluation proofs", commitments.len()));
359 let g = vk.g.to_projective();
360 let gamma_g = vk.gamma_g.to_projective();
361
362 let mut total_c = <E::G1Projective>::zero();
363 let mut total_w = <E::G1Projective>::zero();
364
365 let combination_time = start_timer!(|| "Combining commitments and proofs");
366 let mut randomizer = E::Fr::one();
367 let mut g_multiplier = E::Fr::zero();
370 let mut gamma_g_multiplier = E::Fr::zero();
371 ensure!(commitments.len() == points.len());
372 ensure!(commitments.len() == values.len());
373 ensure!(commitments.len() == proofs.len());
374 for (((c, z), v), proof) in commitments.iter().zip_eq(points).zip_eq(values).zip_eq(proofs) {
375 let w = proof.w;
376 let mut temp = w.mul(*z);
377 temp.add_assign_mixed(&c.0);
378 let c = temp;
379 g_multiplier += &(randomizer * v);
380 if let Some(random_v) = proof.random_v {
381 gamma_g_multiplier += &(randomizer * random_v);
382 }
383 total_c += &c.mul(randomizer);
384 total_w += &w.mul(randomizer);
385 randomizer = u128::rand(rng).into();
388 }
389 total_c -= &g.mul(g_multiplier);
390 total_c -= &gamma_g.mul(gamma_g_multiplier);
391 end_timer!(combination_time);
392
393 let to_affine_time = start_timer!(|| "Converting results to affine for pairing");
394 let affine_points = E::G1Projective::batch_normalization_into_affine(vec![-total_w, total_c]);
395 let (total_w, total_c) = (affine_points[0], affine_points[1]);
396 end_timer!(to_affine_time);
397
398 let pairing_time = start_timer!(|| "Performing product of pairings");
399 let result = E::product_of_pairings(
400 [(&total_w.prepare(), &vk.prepared_beta_h), (&total_c.prepare(), &vk.prepared_h)].iter().copied(),
401 )
402 .is_one();
403 end_timer!(pairing_time);
404 end_timer!(check_time, || format!("Result: {result}"));
405 Ok(result)
406 }
407
408 pub(crate) fn check_degree_is_too_large(degree: usize, num_powers: usize) -> Result<(), PCError> {
409 let num_coefficients = degree + 1;
410 if num_coefficients > num_powers {
411 Err(PCError::TooManyCoefficients { num_coefficients, num_powers })
412 } else {
413 Ok(())
414 }
415 }
416
417 pub(crate) fn check_hiding_bound(hiding_poly_degree: usize, num_powers: usize) -> Result<(), PCError> {
418 if hiding_poly_degree == 0 {
419 Err(PCError::HidingBoundIsZero)
420 } else if hiding_poly_degree >= num_powers {
421 Err(PCError::HidingBoundToolarge { hiding_poly_degree, num_powers })
424 } else {
425 Ok(())
426 }
427 }
428
429 pub(crate) fn check_degrees_and_bounds<'a>(
430 max_degree: usize,
431 enforced_degree_bounds: Option<&[usize]>,
432 p: impl Into<LabeledPolynomialWithBasis<'a, E::Fr>>,
433 ) -> Result<(), PCError> {
434 let p = p.into();
435 if let Some(bound) = p.degree_bound() {
436 let enforced_degree_bounds = enforced_degree_bounds.ok_or(PCError::UnsupportedDegreeBound(bound))?;
437
438 if enforced_degree_bounds.binary_search(&bound).is_err() {
439 Err(PCError::UnsupportedDegreeBound(bound))
440 } else if bound < p.degree() || bound > max_degree {
441 Err(PCError::IncorrectDegreeBound {
442 poly_degree: p.degree(),
443 degree_bound: p.degree_bound().unwrap(),
444 max_degree,
445 label: p.label().to_string(),
446 })
447 } else {
448 Ok(())
449 }
450 } else {
451 Ok(())
452 }
453 }
454}
455
456fn skip_leading_zeros_and_convert_to_bigints<F: PrimeField>(p: &DensePolynomial<F>) -> (usize, Vec<F::BigInteger>) {
457 if p.coeffs.is_empty() {
458 (0, vec![])
459 } else {
460 let num_leading_zeros = p.coeffs.iter().take_while(|c| c.is_zero()).count();
461 let coeffs = if num_leading_zeros == p.coeffs.len() {
462 vec![]
463 } else {
464 convert_to_bigints(&p.coeffs[num_leading_zeros..])
465 };
466 (num_leading_zeros, coeffs)
467 }
468}
469
470fn convert_to_bigints<F: PrimeField>(p: &[F]) -> Vec<F::BigInteger> {
471 let to_bigint_time = start_timer!(|| "Converting polynomial coeffs to bigints");
472 let coeffs = p.iter().map(|s| s.to_bigint()).collect::<Vec<_>>();
473 end_timer!(to_bigint_time);
474 coeffs
475}
476
477#[cfg(test)]
478mod tests {
479 #![allow(non_camel_case_types)]
480 #![allow(clippy::needless_borrow)]
481 use super::*;
482 use snarkvm_curves::bls12_377::{Bls12_377, Fr};
483 use snarkvm_utilities::{FromBytes, ToBytes, rand::TestRng};
484
485 use rand::RngExt;
486 use std::borrow::Cow;
487
488 type KZG_Bls12_377 = KZG10<Bls12_377>;
489
490 impl<E: PairingEngine> KZG10<E> {
491 pub(crate) fn trim(
494 pp: &UniversalParams<E>,
495 mut supported_degree: usize,
496 hiding_bound: Option<usize>,
497 ) -> (Powers<'_, E>, VerifierKey<E>) {
498 if supported_degree == 1 {
499 supported_degree += 1;
500 }
501 let powers_of_beta_g = pp.powers_of_beta_g(0, supported_degree + 1).unwrap().to_vec();
502
503 let powers_of_beta_times_gamma_g = if let Some(hiding_bound) = hiding_bound {
504 (0..=(hiding_bound + 1)).map(|i| pp.powers_of_beta_times_gamma_g()[&i]).collect()
505 } else {
506 vec![]
507 };
508
509 let powers = Powers {
510 powers_of_beta_g: Cow::Owned(powers_of_beta_g),
511 powers_of_beta_times_gamma_g: Cow::Owned(powers_of_beta_times_gamma_g),
512 };
513 let vk = VerifierKey {
514 g: pp.power_of_beta_g(0).unwrap(),
515 gamma_g: pp.powers_of_beta_times_gamma_g()[&0],
516 h: pp.h,
517 beta_h: pp.beta_h(),
518 prepared_h: pp.prepared_h.clone(),
519 prepared_beta_h: pp.prepared_beta_h.clone(),
520 };
521 (powers, vk)
522 }
523 }
524
525 #[test]
526 fn test_kzg10_universal_params_serialization() {
527 let degree = 4;
528 let pp = KZG_Bls12_377::load_srs(degree).unwrap();
529
530 let pp_bytes = pp.to_bytes_le().unwrap();
531 let pp_recovered: UniversalParams<Bls12_377> = FromBytes::read_le(&pp_bytes[..]).unwrap();
532 let pp_recovered_bytes = pp_recovered.to_bytes_le().unwrap();
533
534 assert_eq!(&pp_bytes, &pp_recovered_bytes);
535 }
536
537 fn end_to_end_test_template<E: PairingEngine>() -> Result<(), PCError> {
538 let rng = &mut TestRng::default();
539 for _ in 0..100 {
540 let degree = rng.random_range(2..20);
541 let pp = KZG10::<E>::load_srs(degree)?;
542 let hiding_bound = Some(1);
543 let (ck, vk) = KZG10::trim(&pp, degree, hiding_bound);
544 let p = DensePolynomial::rand(degree, rng);
545 let (comm, rand) = KZG10::<E>::commit(&ck, &(&p).into(), hiding_bound, Some(rng))?;
546 let point = E::Fr::rand(rng);
547 let value = p.evaluate(point);
548 let proof = KZG10::<E>::open(&ck, &p, point, &rand)?;
549 assert!(
550 KZG10::<E>::check(&vk, &comm, point, value, &proof)?,
551 "proof was incorrect for max_degree = {}, polynomial_degree = {}, hiding_bound = {:?}",
552 degree,
553 p.degree(),
554 hiding_bound,
555 );
556 }
557 Ok(())
558 }
559
560 fn linear_polynomial_test_template<E: PairingEngine>() -> Result<(), PCError> {
561 let rng = &mut TestRng::default();
562 for _ in 0..100 {
563 let degree = 50;
564 let pp = KZG10::<E>::load_srs(degree)?;
565 let hiding_bound = Some(1);
566 let (ck, vk) = KZG10::trim(&pp, 2, hiding_bound);
567 let p = DensePolynomial::rand(1, rng);
568 let (comm, rand) = KZG10::<E>::commit(&ck, &(&p).into(), hiding_bound, Some(rng))?;
569 let point = E::Fr::rand(rng);
570 let value = p.evaluate(point);
571 let proof = KZG10::<E>::open(&ck, &p, point, &rand)?;
572 assert!(
573 KZG10::<E>::check(&vk, &comm, point, value, &proof)?,
574 "proof was incorrect for max_degree = {}, polynomial_degree = {}, hiding_bound = {:?}",
575 degree,
576 p.degree(),
577 hiding_bound,
578 );
579 }
580 Ok(())
581 }
582
583 fn batch_check_test_template<E: PairingEngine>() -> Result<(), PCError> {
584 let rng = &mut TestRng::default();
585 for _ in 0..10 {
586 let hiding_bound = Some(1);
587 let degree = rng.random_range(2..20);
588 let pp = KZG10::<E>::load_srs(degree)?;
589 let (ck, vk) = KZG10::trim(&pp, degree, hiding_bound);
590
591 let mut comms = Vec::new();
592 let mut values = Vec::new();
593 let mut points = Vec::new();
594 let mut proofs = Vec::new();
595
596 for _ in 0..10 {
597 let p = DensePolynomial::rand(degree, rng);
598 let (comm, rand) = KZG10::<E>::commit(&ck, &(&p).into(), hiding_bound, Some(rng))?;
599 let point = E::Fr::rand(rng);
600 let value = p.evaluate(point);
601 let proof = KZG10::<E>::open(&ck, &p, point, &rand)?;
602
603 assert!(KZG10::<E>::check(&vk, &comm, point, value, &proof)?);
604 comms.push(comm);
605 values.push(value);
606 points.push(point);
607 proofs.push(proof);
608 }
609 assert!(KZG10::<E>::batch_check(&vk, &comms, &points, &values, &proofs, rng)?);
610 }
611 Ok(())
612 }
613
614 #[test]
615 fn test_end_to_end() {
616 end_to_end_test_template::<Bls12_377>().expect("test failed for bls12-377");
617 }
618
619 #[test]
620 fn test_linear_polynomial() {
621 linear_polynomial_test_template::<Bls12_377>().expect("test failed for bls12-377");
622 }
623
624 #[test]
625 fn test_batch_check() {
626 batch_check_test_template::<Bls12_377>().expect("test failed for bls12-377");
627 }
628
629 #[test]
630 fn test_degree_is_too_large() {
631 let rng = &mut TestRng::default();
632
633 let max_degree = 123;
634 let pp = KZG_Bls12_377::load_srs(max_degree).unwrap();
635 let (powers, _) = KZG_Bls12_377::trim(&pp, max_degree, None);
636
637 let p = DensePolynomial::<Fr>::rand(max_degree + 1, rng);
638 assert!(p.degree() > max_degree);
639 assert!(KZG_Bls12_377::check_degree_is_too_large(p.degree(), powers.size()).is_err());
640 }
641}