上篇?章中,我们研读了?ZKSync?中?better_cs?如何?成?single proof、aggregation proof?的电路逻辑等实现。在这篇?章中,我们继续研读?ZKSync?的聚合证明,我们重点关注?better_better_cs?如何?成聚合证明。 还是?上?篇的这张代码调?图,我们这篇着重讲?create_proof。 我们分析的?bellman_ce?代码版本是?beta?分?,commit id?为48441155ec7006bf7bfac553b5fb7d466d7fcd00?。 aggregation_proof?的?成create_proof?这个函数在?bellman_ce/src/plonk/better_better_cs/proof/mod.rs?中,将近?2000??代码。 ?体上,分为以下?个步骤: 1.?基本的?些检查和预计算// ... for?idx?in?0..num_state_polys?{ let?key?=?PolyIdentifier::PermutationPolynomial(idx); let?vals?=?setup.permutation_monomials[idx].clone().fft_using_bitreversed_ntt( &worker, &omegas_bitreversed, &E::Fr::one() )?.into_coeffs(); let?poly?=?Polynomial::from_values_unpadded(vals)?; let?poly?=?PolynomialProxy::from_owned(poly); values_storage.setup_map.insert(key,?poly); } 2.??成?state?多项式状态和?witness?多项式状态,且为lookup table?参数?成排序好的多项式 // ... proof.state_polys_commitments.push(commitment); // ... proof.witness_polys_commitments.push(commitment); 3.?构造?lookupdataholder,?于后续计算 // ... let?data?=?data_structures::LookupDataHolder::<E>?{ eta, f_poly_unpadded_values:?Some(f_poly_values_aggregated), t_poly_unpadded_values:?Some(t_poly_values), t_shifted_unpadded_values:?Some(t_poly_values_shifted), s_poly_unpadded_values:?Some(s_poly_unpadded_values), s_shifted_unpadded_values:?Some(s_shifted_unpadded_values), t_poly_monomial:?Some(t_poly_monomial), s_poly_monomial:?Some(s_poly_monomial), selector_poly_monomial:?Some(selector_poly), table_type_poly_monomial:?Some(table_type_mononial), }; 4.?对置换多项式进?乘积(grand product)计算 // ... let mut?z_2?=?grand_products_proto_it.next().unwrap(); z_2.add_assign_scaled(&worker,?permutation_polys_it.next().unwrap(), &beta_for_copy_permutation); for?(mut p,?perm)?in?grand_products_proto_it.zip(permutation_polys_it) { p.add_assign_scaled(&worker, &perm, &beta_for_copy_permutation); z_2.mul_assign(&worker, &p); } z_2.batch_inversion(&worker)?; 5.?对商多项式进?计算 // ... let mut?t?=?gate.contribute_into_quotient_for_public_inputs( required_domain_size, &input_values, &mut ldes_storage, &monomials_storage, for_gate, &omegas_bitreversed, &omegas_inv_bitreversed, &worker )?; // ... transcript.commit_field_element(&quotient_at_z); proof.quotient_poly_opening_at_z?=?quotient_at_z; 6.?根据?lookup table?进?线性化 let?queries_with_linearization?=?sort_queries_for_linearization(&self.sorted_gates, MAX_DILATION); // ... for?(dilation_value,?ids)?in queries_with_linearization.state_polys.iter().enumerate() {...} for?(dilation_value,?ids)?in queries_with_linearization.witness_polys.iter().enumerate() {...} for?(gate_idx,?queries)?in queries_with_linearization.gate_setup_polys.iter().enumerate() {...} 7.?对多项式的?selectors?进??open?取值 let mut?selector_values?=?vec![]; for?s?in?queries_with_linearization.gate_selectors.iter() { let?gate_index?=?self.sorted_gates.iter().position(|r|?r?==?s).unwrap(); let?key?=?PolyIdentifier::GateSelector(s.name()); let?poly_ref?=?monomials_storage.gate_selectors.get(&key).unwrap().as_ref(); let?value?=?poly_ref.evaluate_at(&worker,?z); transcript.commit_field_element(&value); proof.gate_selectors_openings_at_z.push((gate_index,?value)); selector_values.push(value); } 8.?增加拷?置换多项式、lookup置换的优化结果// ... r_poly.add_assign_scaled(&worker, &copy_permutation_z_in_monomial_form, &factor); r_poly.sub_assign_scaled(&worker,?last_permutation_poly_ref, &factor); r_poly.add_assign_scaled(&worker, &copy_permutation_z_in_monomial_form, &factor); 9.?使??lookup?进??query let?query?=?LookupQuery::<E>?{ s_at_z_omega, grand_product_at_z_omega, t_at_z, t_at_z_omega, selector_at_z, table_type_at_z, }; 10.?对多项式的?selectors?在?z?进??open?取值 for?s?in?queries_with_linearization.gate_selectors.iter() { multiopening_challenge.mul_assign(&v); let?key?=?PolyIdentifier::GateSelector(s.name()); let?poly_ref?=?monomials_storage.get_poly(key); poly_to_divide_at_z.add_assign_scaled(&worker,?poly_ref, &multiopening_challenge); } 11.?将最终的?lookup?值放?proof中 if let?Some(data)?=?lookup_data.as_ref() { // we need to add t(x), selector(x) and table type(x) multiopening_challenge.mul_assign(&v); let?poly_ref?=?data.t_poly_monomial.as_ref().unwrap().as_ref(); poly_to_divide_at_z.add_assign_scaled(&worker,?poly_ref, &multiopening_challenge); multiopening_challenge.mul_assign(&v); let?poly_ref?=?data.selector_poly_monomial.as_ref().unwrap().as_ref(); poly_to_divide_at_z.add_assign_scaled(&worker,?poly_ref, &multiopening_challenge); multiopening_challenge.mul_assign(&v); let?poly_ref?=?data.table_type_poly_monomial.as_ref().unwrap().as_ref(); poly_to_divide_at_z.add_assign_scaled(&worker,?poly_ref, &multiopening_challenge); } 12.?计算?z、z_omega?处的?open?值,最后组装?proof?在这个函数中,我们看到了熟悉的?MainGate?函数,从上?版如何实现聚合中,我们知道这个?于?的 设计,可以实现?custom gate,达到优化电路的?的。?除开?custom gate,ZKSync?中还使?了 plonkup(即?plonk + lookup table) 来提升效率。 我们在之前的?章中,已经讲解过plonkup的原理了,简单来说,就是预计算有效的input/output组成 lookup table,prover需要证明witness在这个table?,详细内容请参?ZKSwap团队解读Plookup原理。 ZKSync?对?plonkup?的实现,并不是将?custom gate?和?plonkup?分开的,?是结合在?起来优化电路设计的。 我们下?看看,MainGate trait?中的接?,是如何和?plonkup?结合的。 lookup?的使? 在上?节的?create_proof?函数中,线性化?到了?gate?的 contribute_into_linearization_for_public_inputs?函数,我们以它为例,来看看?lookup?的使?。这个代码在?bellman_ce/src/plonk/better_better_cs/cs.rs?中。 let?open_at_z_omega?=?polys.pop().unwrap().0; let?open_at_z?=?polys.pop().unwrap().0; let?opening_at_z?=?commit_using_monomials( &open_at_z, &mon_crs, &worker )?; let?opening_at_z_omega?=?commit_using_monomials( &open_at_z_omega, &mon_crs, &worker )?; proof.opening_proof_at_z?=?opening_at_z; proof.opening_proof_at_z_omega?=?opening_at_z_omega;fn?contribute_into_linearization_for_public_inputs( &self, _domain_size:?usize, _public_inputs: &[E::Fr], _at:?E::Fr, queried_values: &std::collections::HashMap<PolynomialInConstraint,?E::Fr>, monomials_storage: &?AssembledPolynomialStorageForMonomialForms<E>, challenges: &[E::Fr], worker: &Worker )?->?Result<Polynomial<E::Fr,?Coefficients>,?SynthesisError>?{} ?到的传?参数有?hashmap?格式的?queried_values、单项式缓存值、随机数数组。queried_values?这个参数是在?create_proof?时,根据排序的query?列表?成的,key?是多项式,value是?Fr?值。query?列表的排序规则是先witness、gate?的selector?次之、gate?的setup?再次之,这个?SortedGateQueries?的结构是: pub struct?SortedGateQueries<E:?Engine>{ pub?state_polys:?Vec<Vec<PolyIdentifier>>,?// state?多项式 pub?witness_polys:?Vec<Vec<PolyIdentifier>>,?// witness?多项式 pub?gate_selectors:?Vec<Box<dyn GateInternal<E>>>,?// gate?的selectors pub?gate_setup_polys:?Vec<Vec<Vec<PolyIdentifier>>>,?// gate setup?多项式 } 代码中,调??sort_queries_for_linearization?函数来?成?SortedGateQueries?,这个函数也在当 前?mod.rs??件中。这个函数输?参数是?gate?数组,输出即为?SortedGateQueries?。 fn?sort_queries_for_linearization<E:?Engine>(gates: &?Vec<Box<dyn GateInternal<E>>>, max_dilation:?usize) ->?SortedGateQueries<E>?{ } 函数会对传?的?gate?数组遍历,根据gate返回的多项式数组,将其按照?VariablesPolynomial?, WitnessPolynomial?,?GateSetupPolynomial?的不同类型,将多项式存??SortedGateQueries?中。 回到?contribute_into_linearization_for_public_inputs?函数,可以看到,它会从queried_values 中,获取?a/b/c/d?的值。??Q_a/Q_b/Q_c/Q_d/Q_m的值,都是从?create_proof?刚开始?成的单项式缓存数据中取到的,也是?个lookup table?的概念 这个单项式缓存的值是从电路的setup?获得的,即电路确定了,那么电路的?就确定了,则在?成proof时,这些数据都已经有了,可以直接将setup?预计算的结果,放??lookup table?中,查询使?数据。let mut?monomials_storage?=?Self::create_monomial_storage( &worker, &omegas_inv_bitreversed, &values_storage, true )?; monomials_storage.extend_from_setup(setup)?; 最后,结合a/b/c/d和Q_a/Q_b/Q_c/Q_d,可以?常?便的构造出多项式。 //?可以看到,?常?效的get取到了数据 let?a_value?= *queried_values.get(&PolynomialInConstraint::from_id(PolyIdentifier::VariablesPolynomia l(0))) .ok_or(SynthesisError::AssignmentMissing)?; let?b_value?= *queried_values.get(&PolynomialInConstraint::from_id(PolyIdentifier::VariablesPolynomia l(1))) .ok_or(SynthesisError::AssignmentMissing)?; let?c_value?= *queried_values.get(&PolynomialInConstraint::from_id(PolyIdentifier::VariablesPolynomia l(2))) .ok_or(SynthesisError::AssignmentMissing)?; let?d_value?= *queried_values.get(&PolynomialInConstraint::from_id(PolyIdentifier::VariablesPolynomia l(3))) .ok_or(SynthesisError::AssignmentMissing)?; let?d_next_value?= *queried_values.get(&PolynomialInConstraint::from_id_and_dilation(PolyIdentifier::Varia blesPolynomial(3),?1)) .ok_or(SynthesisError::AssignmentMissing)?; let?name?= <Self?as?GateInternal<E>>::name(&self); // get_ploy?也是查找table的?式获取多项式 // Q_a * A let mut?result?=?monomials_storage.get_poly(PolyIdentifier::GateSetupPolynomial(name, 0)).clone(); result.scale(&worker,?a_value); // Q_b * B let?poly_ref?=?monomials_storage.get_poly(PolyIdentifier::GateSetupPolynomial(name, 1)); result.add_assign_scaled(&worker,?poly_ref, &b_value); // Q_c * Clet?poly_ref?=?monomials_storage.get_poly(PolyIdentifier::GateSetupPolynomial(name, 2)); result.add_assign_scaled(&worker,?poly_ref, &c_value); // Q_d * D let?poly_ref?=?monomials_storage.get_poly(PolyIdentifier::GateSetupPolynomial(name, 3)); result.add_assign_scaled(&worker,?poly_ref, &d_value); // Q_m * A*B let mut?tmp?=?a_value; tmp.mul_assign(&b_value); let?poly_ref?=?monomials_storage.get_poly(PolyIdentifier::GateSetupPolynomial(name, 4)); result.add_assign_scaled(&worker,?poly_ref, &tmp); // Q_const let?poly_ref?=?monomials_storage.get_poly(PolyIdentifier::GateSetupPolynomial(name, 5)); result.add_assign(&worker,?poly_ref); // Q_dNext * D_next let?poly_ref?=?monomials_storage.get_poly(PolyIdentifier::GateSetupPolynomial(name, 6)); result.add_assign_scaled(&worker,?poly_ref, &d_next_value); result.scale(&worker,?challenges[0]); //?结果都存?result中 Ok(result) 另外?个?MainGate??的接?函数,都是?样的,结合lookup table,?常容易的计算出多项式。 综上,ZKSync?将witness、gate?的?selector、setup?放?lookup table?中,在?成?proof?时,使?lookup table,直接查询?不是再次计算,加快?成速度,提升?prover?效率。 —- 编译者/作者:ZKSwap 玩币族申明:玩币族作为开放的资讯翻译/分享平台,所提供的所有资讯仅代表作者个人观点,与玩币族平台立场无关,且不构成任何投资理财建议。文章版权归原作者所有。 |
ZKSync中better_better_cs如何实现聚合证明(?)
2021-06-08 ZKSwap 来源:区块链网络
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