Separate prover and verifier keys in CompressedSNARK (#145)

* checkpoint

* simplify further

* checkpoint

* gens --> ck

* update benches

* address clippy

* cleanup

* update version

src/traits/commitment.rs

@@ -12,7 +12,7 @@ use serde::{Deserialize, Serialize};
 
 /// This trait defines the behavior of commitment key
 #[allow(clippy::len_without_is_empty)]
-pub trait CommitmentGensTrait<G: Group>:
+pub trait CommitmentKeyTrait<G: Group>:
   Clone + Debug + Send + Sync + Serialize + for<'de> Deserialize<'de>
 {
   /// Holds the type of the commitment that can be produced
@@ -99,11 +99,11 @@ pub trait CommitmentEngineTrait<G: Group>:
   Clone + Send + Sync + Serialize + for<'de> Deserialize<'de>
 {
   /// Holds the type of the commitment key
-  type CommitmentGens: CommitmentGensTrait<G, Commitment = Self::Commitment>;
+  type CommitmentKey: CommitmentKeyTrait<G, Commitment = Self::Commitment>;
 
   /// Holds the type of the commitment
   type Commitment: CommitmentTrait<G>;
 
   /// Commits to the provided vector using the provided generators
-  fn commit(gens: &Self::CommitmentGens, v: &[G::Scalar]) -> Self::Commitment;
+  fn commit(ck: &Self::CommitmentKey, v: &[G::Scalar]) -> Self::Commitment;
 }

src/traits/evaluation.rs

@@ -14,18 +14,24 @@ pub trait EvaluationEngineTrait<G: Group>:
   /// A type that holds the associated commitment engine
   type CE: CommitmentEngineTrait<G>;
 
-  /// A type that holds generators
-  type EvaluationGens: Clone + Send + Sync + Serialize + for<'de> Deserialize<'de>;
+  /// A type that holds the prover key
+  type ProverKey: Clone + Send + Sync + Serialize + for<'de> Deserialize<'de>;
+
+  /// A type that holds the verifier key
+  type VerifierKey: Clone + Send + Sync + Serialize + for<'de> Deserialize<'de>;
 
   /// A type that holds the evaluation argument
   type EvaluationArgument: Clone + Send + Sync + Serialize + for<'de> Deserialize<'de>;
 
   /// A method to perform any additional setup needed to produce proofs of evaluations
-  fn setup(gens: &<Self::CE as CommitmentEngineTrait<G>>::CommitmentGens) -> Self::EvaluationGens;
+  fn setup(
+    ck: &<Self::CE as CommitmentEngineTrait<G>>::CommitmentKey,
+  ) -> (Self::ProverKey, Self::VerifierKey);
 
   /// A method to prove the evaluation of a multilinear polynomial
   fn prove(
-    gens: &Self::EvaluationGens,
+    ck: &<Self::CE as CommitmentEngineTrait<G>>::CommitmentKey,
+    pk: &Self::ProverKey,
     transcript: &mut G::TE,
     comm: &<Self::CE as CommitmentEngineTrait<G>>::Commitment,
     poly: &[G::Scalar],
@@ -35,7 +41,7 @@ pub trait EvaluationEngineTrait<G: Group>:
 
   /// A method to verify the purported evaluation of a multilinear polynomials
   fn verify(
-    gens: &Self::EvaluationGens,
+    vk: &Self::VerifierKey,
     transcript: &mut G::TE,
     comm: &<Self::CE as CommitmentEngineTrait<G>>::Commitment,
     point: &[G::Scalar],

src/traits/snark.rs

@@ -1,46 +1,29 @@
 //! This module defines a collection of traits that define the behavior of a zkSNARK for RelaxedR1CS
 use crate::{
   errors::NovaError,
-  r1cs::{R1CSGens, R1CSShape, RelaxedR1CSInstance, RelaxedR1CSWitness},
+  r1cs::{R1CSShape, RelaxedR1CSInstance, RelaxedR1CSWitness},
   traits::Group,
+  CommitmentKey,
 };
 
 use serde::{Deserialize, Serialize};
 
-/// A trait that defines the behavior of a zkSNARK's prover key
-pub trait ProverKeyTrait<G: Group>: Send + Sync {
-  /// Produces a new prover's key
-  fn new(gens: &R1CSGens<G>, S: &R1CSShape<G>) -> Self;
-}
-
-/// A trait that defines the behavior of a zkSNARK's verifier key
-pub trait VerifierKeyTrait<G: Group>: Send + Sync {
-  /// Produces a new verifier's key
-  fn new(gens: &R1CSGens<G>, S: &R1CSShape<G>) -> Self;
-}
-
 /// A trait that defines the behavior of a zkSNARK
 pub trait RelaxedR1CSSNARKTrait<G: Group>:
   Sized + Send + Sync + Serialize + for<'de> Deserialize<'de>
 {
   /// A type that represents the prover's key
-  type ProverKey: ProverKeyTrait<G> + Serialize + for<'de> Deserialize<'de>;
+  type ProverKey: Send + Sync + Serialize + for<'de> Deserialize<'de>;
 
   /// A type that represents the verifier's key
-  type VerifierKey: VerifierKeyTrait<G> + Serialize + for<'de> Deserialize<'de>;
+  type VerifierKey: Send + Sync + Serialize + for<'de> Deserialize<'de>;
 
-  /// Produces a prover key
-  fn prover_key(gens: &R1CSGens<G>, S: &R1CSShape<G>) -> Self::ProverKey {
-    Self::ProverKey::new(gens, S)
-  }
-
-  /// Produces a verifier key
-  fn verifier_key(gens: &R1CSGens<G>, S: &R1CSShape<G>) -> Self::VerifierKey {
-    Self::VerifierKey::new(gens, S)
-  }
+  /// Produces the keys for the prover and the verifier
+  fn setup(ck: &CommitmentKey<G>, S: &R1CSShape<G>) -> (Self::ProverKey, Self::VerifierKey);
 
   /// Produces a new SNARK for a relaxed R1CS
   fn prove(
+    ck: &CommitmentKey<G>,
     pk: &Self::ProverKey,
     U: &RelaxedR1CSInstance<G>,
     W: &RelaxedR1CSWitness<G>,