Adds Absorb and AbsorbGadget impl for Groth Verification Key & Var (#53)

Co-authored-by: Pratyush Mishra <pratyushmishra@berkeley.edu>
arkworks-rs · Jan 17, 2024 · 8e5c347 · 8e5c347
1 parent 596d91f
commit 8e5c347
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Showing 3 changed files with 80 additions and 13 deletions.
diff --git a/Cargo.toml b/Cargo.toml
@@ -21,7 +21,7 @@ ark-serialize = { version = "0.4.0", default-features = false, features = [ "der
 ark-poly = { version = "0.4.0", default-features = false }
 ark-std = { version = "0.4.0", default-features = false }
 ark-relations = { version = "0.4.0", default-features = false }
-ark-crypto-primitives = { version = "0.4.0", default-features = false, features = ["snark"] }
+ark-crypto-primitives = { version = "0.4.0", default-features = false, features = ["snark", "sponge"] }
 ark-r1cs-std = { version = "0.4.0", default-features = false, optional = true }
 
 tracing = { version = "0.1", default-features = false, features = [ "attributes" ], optional = true }

diff --git a/src/constraints.rs b/src/constraints.rs
@@ -2,16 +2,22 @@ use crate::{
     r1cs_to_qap::{LibsnarkReduction, R1CSToQAP},
     Groth16, PreparedVerifyingKey, Proof, VerifyingKey,
 };
-use ark_crypto_primitives::snark::constraints::{CircuitSpecificSetupSNARKGadget, SNARKGadget};
-use ark_crypto_primitives::snark::{BooleanInputVar, SNARK};
+use ark_crypto_primitives::{
+    snark::{
+        constraints::{CircuitSpecificSetupSNARKGadget, SNARKGadget},
+        BooleanInputVar, SNARK,
+    },
+    sponge::constraints::AbsorbGadget,
+};
 use ark_ec::{pairing::Pairing, AffineRepr};
 use ark_ff::Field;
-use ark_r1cs_std::groups::CurveVar;
 use ark_r1cs_std::{
     alloc::{AllocVar, AllocationMode},
     boolean::Boolean,
     convert::{ToBitsGadget, ToBytesGadget},
     eq::EqGadget,
+    fields::fp::FpVar,
+    groups::CurveVar,
     pairing::PairingVar,
     uint8::UInt8,
 };
@@ -69,7 +75,42 @@ impl<E: Pairing, P: PairingVar<E>> VerifyingKeyVar<E, P> {
     }
 }
 
-/// Preprocessed verification key parameters variable for the Groth16 construction
+impl<E, P> AbsorbGadget<E::BaseField> for VerifyingKeyVar<E, P>
+where
+    E: Pairing,
+    P: PairingVar<E>,
+    P::G1Var: AbsorbGadget<E::BaseField>,
+    P::G2Var: AbsorbGadget<E::BaseField>,
+{
+    fn to_sponge_bytes(&self) -> Result<Vec<UInt8<<E as Pairing>::BaseField>>, SynthesisError> {
+        let mut bytes = self.alpha_g1.to_sponge_bytes()?;
+        bytes.extend(self.beta_g2.to_sponge_bytes()?);
+        bytes.extend(self.gamma_g2.to_sponge_bytes()?);
+        bytes.extend(self.delta_g2.to_sponge_bytes()?);
+        self.gamma_abc_g1.iter().try_for_each(|g| {
+            bytes.extend(g.to_sponge_bytes()?);
+            Ok(())
+        })?;
+        Ok(bytes)
+    }
+
+    fn to_sponge_field_elements(
+        &self,
+    ) -> Result<Vec<FpVar<<E as Pairing>::BaseField>>, SynthesisError> {
+        let mut field_elements = self.alpha_g1.to_sponge_field_elements()?;
+        field_elements.extend(self.beta_g2.to_sponge_field_elements()?);
+        field_elements.extend(self.gamma_g2.to_sponge_field_elements()?);
+        field_elements.extend(self.delta_g2.to_sponge_field_elements()?);
+        self.gamma_abc_g1.iter().try_for_each(|g| {
+            field_elements.extend(g.to_sponge_field_elements()?);
+            Ok(())
+        })?;
+        Ok(field_elements)
+    }
+}
+
+/// Preprocessed verification key parameters variable for the Groth16
+/// construction
 #[derive(Derivative)]
 #[derivative(
     Clone(bound = "P::G1Var: Clone, P::GTVar: Clone, P::G1PreparedVar: Clone, \
@@ -411,22 +452,20 @@ where
 #[cfg(test)]
 mod test {
     use crate::{constraints::Groth16VerifierGadget, Groth16};
-    use ark_crypto_primitives::snark::constraints::SNARKGadget;
-    use ark_crypto_primitives::snark::SNARK;
+    use ark_crypto_primitives::snark::{constraints::SNARKGadget, SNARK};
     use ark_ec::pairing::Pairing;
     use ark_ff::{Field, UniformRand};
     use ark_mnt4_298::{constraints::PairingVar as MNT4PairingVar, Fr as MNT4Fr, MNT4_298 as MNT4};
     use ark_mnt6_298::Fr as MNT6Fr;
-    use ark_r1cs_std::boolean::Boolean;
-    use ark_r1cs_std::{alloc::AllocVar, eq::EqGadget};
+    use ark_r1cs_std::{alloc::AllocVar, boolean::Boolean, eq::EqGadget};
     use ark_relations::{
         lc, ns,
         r1cs::{ConstraintSynthesizer, ConstraintSystem, ConstraintSystemRef, SynthesisError},
     };
-    use ark_std::test_rng;
     use ark_std::{
         ops::MulAssign,
         rand::{RngCore, SeedableRng},
+        test_rng,
     };
 
     #[derive(Copy, Clone)]

diff --git a/src/data_structures.rs b/src/data_structures.rs
@@ -1,4 +1,6 @@
+use ark_crypto_primitives::sponge::Absorb;
 use ark_ec::pairing::Pairing;
+use ark_ff::PrimeField;
 use ark_serialize::*;
 use ark_std::vec::Vec;
 
@@ -23,7 +25,6 @@ impl<E: Pairing> Default for Proof<E> {
     }
 }
 
-////////////////////////////////////////////////////////////////////////////////
 ////////////////////////////////////////////////////////////////////////////////
 
 /// A verification key in the Groth16 SNARK.
@@ -37,7 +38,8 @@ pub struct VerifyingKey<E: Pairing> {
     pub gamma_g2: E::G2Affine,
     /// The `delta * H`, where `H` is the generator of `E::G2`.
     pub delta_g2: E::G2Affine,
-    /// The `gamma^{-1} * (beta * a_i + alpha * b_i + c_i) * H`, where `H` is the generator of `E::G1`.
+    /// The `gamma^{-1} * (beta * a_i + alpha * b_i + c_i) * H`, where `H` is
+    /// the generator of `E::G1`.
     pub gamma_abc_g1: Vec<E::G1Affine>,
 }
 
@@ -53,6 +55,33 @@ impl<E: Pairing> Default for VerifyingKey<E> {
     }
 }
 
+impl<E> Absorb for VerifyingKey<E>
+where
+    E: Pairing,
+    E::G1Affine: Absorb,
+    E::G2Affine: Absorb,
+{
+    fn to_sponge_bytes(&self, dest: &mut Vec<u8>) {
+        self.alpha_g1.to_sponge_bytes(dest);
+        self.beta_g2.to_sponge_bytes(dest);
+        self.gamma_g2.to_sponge_bytes(dest);
+        self.delta_g2.to_sponge_bytes(dest);
+        self.gamma_abc_g1
+            .iter()
+            .for_each(|g| g.to_sponge_bytes(dest));
+    }
+
+    fn to_sponge_field_elements<F: PrimeField>(&self, dest: &mut Vec<F>) {
+        self.alpha_g1.to_sponge_field_elements(dest);
+        self.beta_g2.to_sponge_field_elements(dest);
+        self.gamma_g2.to_sponge_field_elements(dest);
+        self.delta_g2.to_sponge_field_elements(dest);
+        self.gamma_abc_g1
+            .iter()
+            .for_each(|g| g.to_sponge_field_elements(dest));
+    }
+}
+
 /// Preprocessed verification key parameters that enable faster verification
 /// at the expense of larger size in memory.
 #[derive(Clone, Debug, PartialEq, CanonicalSerialize, CanonicalDeserialize)]
@@ -90,7 +119,6 @@ impl<E: Pairing> Default for PreparedVerifyingKey<E> {
     }
 }
 
-////////////////////////////////////////////////////////////////////////////////
 ////////////////////////////////////////////////////////////////////////////////
 
 /// The prover key for for the Groth16 zkSNARK.