Add FiatShamirRng

Author: vlopes11

src/constraints/ahp.rs

@@ -8,7 +8,7 @@ use crate::{
     sponge::CryptographicSpongeVarNonNative,
     CryptographicSpongeParameters, PhantomData, PrimeField, String, ToString, Vec,
 };
-use ark_nonnative_field::NonNativeFieldVar;
+use ark_nonnative_field::{params::OptimizationType, NonNativeFieldVar};
 use ark_poly::univariate::DensePolynomial;
 use ark_poly_commit::{
     EvaluationsVar, LCTerm, LabeledPointVar, LinearCombinationCoeffVar, LinearCombinationVar,
@@ -103,7 +103,7 @@ where
                 elems.append(&mut comm.to_constraint_field().unwrap());
             });
             sponge_var.absorb(&elems)?;
-            sponge_var.absorb_nonnative(&message)?;
+            sponge_var.absorb_nonnative(&message, OptimizationType::Weight)?;
         }
 
         // obtain four elements from the sponge_var
@@ -153,7 +153,7 @@ where
                 elems.append(&mut comm.to_constraint_field().unwrap());
             });
             sponge_var.absorb(&elems)?;
-            sponge_var.absorb_nonnative(&message)?;
+            sponge_var.absorb_nonnative(&message, OptimizationType::Weight)?;
         }
 
         // obtain one element from the sponge_var
@@ -195,7 +195,7 @@ where
                 elems.append(&mut comm.to_constraint_field().unwrap());
             });
             sponge_var.absorb(&elems)?;
-            sponge_var.absorb_nonnative(&message)?;
+            sponge_var.absorb_nonnative(&message, OptimizationType::Weight)?;
         }
 
         // obtain one element from the sponge_var

src/constraints/verifier.rs

@@ -5,7 +5,7 @@ use crate::{
     CryptographicSpongeParameters, CryptographicSpongeWithRate, Error, PhantomData, PrimeField,
     String, Vec,
 };
-use ark_nonnative_field::NonNativeFieldVar;
+use ark_nonnative_field::{params::OptimizationType, NonNativeFieldVar};
 use ark_poly::univariate::DensePolynomial;
 use ark_poly_commit::{PCCheckRandomDataVar, PCCheckVar, PolynomialCommitment};
 use ark_r1cs_std::{bits::boolean::Boolean, fields::FieldVar, R1CSVar, ToConstraintFieldGadget};
@@ -59,7 +59,7 @@ where
 
         eprintln!("before AHP: constraints: {}", cs.num_constraints());
 
-        sponge_var.absorb_nonnative(&public_input)?;
+        sponge_var.absorb_nonnative(&public_input, OptimizationType::Weight)?;
 
         let (_, verifier_state) = AHPForR1CS::<F, CF, S, SVN, PC, PCG>::verifier_first_round(
             index_pvk.domain_h_size,
@@ -116,7 +116,7 @@ where
             }
         }
 
-        sponge_var.absorb_nonnative(&evals_vec)?;
+        sponge_var.absorb_nonnative(&evals_vec, OptimizationType::Weight)?;
 
         let (opening_challenges, opening_challenges_bits) =
             sponge_var.squeeze_nonnative_field_elements(num_opening_challenges)?;

src/fiat_shamir/constraints.rs

@@ -0,0 +1,301 @@
+use crate::{overhead, Vec};
+use ark_ff::PrimeField;
+use ark_nonnative_field::params::{get_params, OptimizationType};
+use ark_nonnative_field::{AllocatedNonNativeFieldVar, NonNativeFieldVar};
+use ark_r1cs_std::{
+    alloc::AllocVar,
+    bits::{uint8::UInt8, ToBitsGadget},
+    boolean::Boolean,
+    fields::fp::AllocatedFp,
+    fields::fp::FpVar,
+    R1CSVar,
+};
+use ark_relations::lc;
+use ark_relations::r1cs::{
+    ConstraintSystemRef, LinearCombination, OptimizationGoal, SynthesisError,
+};
+use ark_sponge::constraints::{AbsorbGadget, CryptographicSpongeVar};
+use ark_sponge::CryptographicSponge;
+use core::marker::PhantomData;
+
+/// Building the Fiat-Shamir sponge's gadget from any algebraic sponge's gadget.
+#[derive(Clone)]
+pub struct FiatShamirAlgebraicSpongeRngVar<
+    F: PrimeField,
+    CF: PrimeField,
+    PS: CryptographicSponge,
+    S: CryptographicSpongeVar<CF, PS>,
+> {
+    pub cs: ConstraintSystemRef<CF>,
+    pub s: S,
+    #[doc(hidden)]
+    f_phantom: PhantomData<F>,
+    cf_phantom: PhantomData<CF>,
+    ps_phantom: PhantomData<PS>,
+}
+
+impl<F: PrimeField, CF: PrimeField, PS: CryptographicSponge, S: CryptographicSpongeVar<CF, PS>>
+    FiatShamirAlgebraicSpongeRngVar<F, CF, PS, S>
+{
+    /// Compress every two elements if possible. Provides a vector of (limb, num_of_additions),
+    /// both of which are CF.
+    #[tracing::instrument(target = "r1cs")]
+    pub fn compress_gadgets(
+        src_limbs: &[(FpVar<CF>, CF)],
+        ty: OptimizationType,
+    ) -> Result<Vec<FpVar<CF>>, SynthesisError> {
+        let capacity = CF::size_in_bits() - 1;
+        let mut dest_limbs = Vec::<FpVar<CF>>::new();
+
+        if src_limbs.is_empty() {
+            return Ok(vec![]);
+        }
+
+        let params = get_params(F::size_in_bits(), CF::size_in_bits(), ty);
+
+        let adjustment_factor_lookup_table = {
+            let mut table = Vec::<CF>::new();
+
+            let mut cur = CF::one();
+            for _ in 1..=capacity {
+                table.push(cur);
+                cur.double_in_place();
+            }
+
+            table
+        };
+
+        let mut i: usize = 0;
+        let src_len = src_limbs.len();
+        while i < src_len {
+            let first = &src_limbs[i];
+            let second = if i + 1 < src_len {
+                Some(&src_limbs[i + 1])
+            } else {
+                None
+            };
+
+            let first_max_bits_per_limb = params.bits_per_limb + overhead!(first.1 + &CF::one());
+            let second_max_bits_per_limb = if second.is_some() {
+                params.bits_per_limb + overhead!(second.unwrap().1 + &CF::one())
+            } else {
+                0
+            };
+
+            if second.is_some() && first_max_bits_per_limb + second_max_bits_per_limb <= capacity {
+                let adjustment_factor = &adjustment_factor_lookup_table[second_max_bits_per_limb];
+
+                dest_limbs.push(&first.0 * *adjustment_factor + &second.unwrap().0);
+                i += 2;
+            } else {
+                dest_limbs.push(first.0.clone());
+                i += 1;
+            }
+        }
+
+        Ok(dest_limbs)
+    }
+
+    /// Push gadgets to sponge.
+    #[tracing::instrument(target = "r1cs", skip(sponge))]
+    pub fn push_gadgets_to_sponge(
+        sponge: &mut S,
+        src: &[NonNativeFieldVar<F, CF>],
+        ty: OptimizationType,
+    ) -> Result<(), SynthesisError> {
+        let mut src_limbs: Vec<(FpVar<CF>, CF)> = Vec::new();
+
+        for elem in src.iter() {
+            match elem {
+                NonNativeFieldVar::Constant(c) => {
+                    let v = AllocatedNonNativeFieldVar::<F, CF>::new_constant(sponge.cs(), c)?;
+
+                    for limb in v.limbs.iter() {
+                        let num_of_additions_over_normal_form =
+                            if v.num_of_additions_over_normal_form == CF::zero() {
+                                CF::one()
+                            } else {
+                                v.num_of_additions_over_normal_form
+                            };
+                        src_limbs.push((limb.clone(), num_of_additions_over_normal_form));
+                    }
+                }
+                NonNativeFieldVar::Var(v) => {
+                    for limb in v.limbs.iter() {
+                        let num_of_additions_over_normal_form =
+                            if v.num_of_additions_over_normal_form == CF::zero() {
+                                CF::one()
+                            } else {
+                                v.num_of_additions_over_normal_form
+                            };
+                        src_limbs.push((limb.clone(), num_of_additions_over_normal_form));
+                    }
+                }
+            }
+        }
+
+        let dest_limbs = Self::compress_gadgets(&src_limbs, ty)?;
+        sponge.absorb(&dest_limbs)?;
+        Ok(())
+    }
+
+    /// Obtain random bits from hashchain gadget. (Not guaranteed to be uniformly distributed,
+    /// should only be used in certain situations.)
+    #[tracing::instrument(target = "r1cs", skip(sponge))]
+    pub fn get_booleans_from_sponge(
+        sponge: &mut S,
+        num_bits: usize,
+    ) -> Result<Vec<Boolean<CF>>, SynthesisError> {
+        let bits_per_element = CF::size_in_bits() - 1;
+        let num_elements = (num_bits + bits_per_element - 1) / bits_per_element;
+
+        let src_elements = sponge.squeeze_field_elements(num_elements)?;
+        let mut dest_bits = Vec::<Boolean<CF>>::new();
+
+        for elem in src_elements.iter() {
+            let elem_bits = elem.to_bits_be()?;
+            dest_bits.extend_from_slice(&elem_bits[1..]); // discard the highest bit
+        }
+
+        Ok(dest_bits)
+    }
+
+    /// Obtain random elements from hashchain gadget. (Not guaranteed to be uniformly distributed,
+    /// should only be used in certain situations.)
+    #[tracing::instrument(target = "r1cs", skip(sponge))]
+    pub fn get_gadgets_from_sponge(
+        sponge: &mut S,
+        num_elements: usize,
+        outputs_short_elements: bool,
+    ) -> Result<Vec<NonNativeFieldVar<F, CF>>, SynthesisError> {
+        let (dest_gadgets, _) =
+            Self::get_gadgets_and_bits_from_sponge(sponge, num_elements, outputs_short_elements)?;
+
+        Ok(dest_gadgets)
+    }
+
+    /// Obtain random elements, and the corresponding bits, from hashchain gadget. (Not guaranteed
+    /// to be uniformly distributed, should only be used in certain situations.)
+    #[tracing::instrument(target = "r1cs", skip(sponge))]
+    #[allow(clippy::type_complexity)]
+    pub fn get_gadgets_and_bits_from_sponge(
+        sponge: &mut S,
+        num_elements: usize,
+        outputs_short_elements: bool,
+    ) -> Result<(Vec<NonNativeFieldVar<F, CF>>, Vec<Vec<Boolean<CF>>>), SynthesisError> {
+        let cs = sponge.cs();
+
+        let optimization_type = match cs.optimization_goal() {
+            OptimizationGoal::None => OptimizationType::Constraints,
+            OptimizationGoal::Constraints => OptimizationType::Constraints,
+            OptimizationGoal::Weight => OptimizationType::Weight,
+        };
+
+        let params = get_params(F::size_in_bits(), CF::size_in_bits(), optimization_type);
+
+        let num_bits_per_nonnative = if outputs_short_elements {
+            128
+        } else {
+            F::size_in_bits() - 1 // also omit the highest bit
+        };
+        let bits = Self::get_booleans_from_sponge(sponge, num_bits_per_nonnative * num_elements)?;
+
+        let mut lookup_table = Vec::<Vec<CF>>::new();
+        let mut cur = F::one();
+        for _ in 0..num_bits_per_nonnative {
+            let repr = AllocatedNonNativeFieldVar::<F, CF>::get_limbs_representations(
+                &cur,
+                optimization_type,
+            )?;
+            lookup_table.push(repr);
+            cur.double_in_place();
+        }
+
+        let mut dest_gadgets = Vec::<NonNativeFieldVar<F, CF>>::new();
+        let mut dest_bits = Vec::<Vec<Boolean<CF>>>::new();
+        bits.chunks_exact(num_bits_per_nonnative)
+            .for_each(|per_nonnative_bits| {
+                let mut val = vec![CF::zero(); params.num_limbs];
+                let mut lc = vec![LinearCombination::<CF>::zero(); params.num_limbs];
+
+                let mut per_nonnative_bits_le = per_nonnative_bits.to_vec();
+                per_nonnative_bits_le.reverse();
+
+                dest_bits.push(per_nonnative_bits_le.clone());
+
+                for (j, bit) in per_nonnative_bits_le.iter().enumerate() {
+                    if bit.value().unwrap_or_default() {
+                        for (k, val) in val.iter_mut().enumerate().take(params.num_limbs) {
+                            *val += &lookup_table[j][k];
+                        }
+                    }
+
+                    #[allow(clippy::needless_range_loop)]
+                    for k in 0..params.num_limbs {
+                        lc[k] = &lc[k] + bit.lc() * lookup_table[j][k];
+                    }
+                }
+
+                let mut limbs = Vec::new();
+                for k in 0..params.num_limbs {
+                    let gadget =
+                        AllocatedFp::new_witness(ark_relations::ns!(cs, "alloc"), || Ok(val[k]))
+                            .unwrap();
+                    lc[k] = lc[k].clone() - (CF::one(), gadget.variable);
+                    cs.enforce_constraint(lc!(), lc!(), lc[k].clone()).unwrap();
+                    limbs.push(FpVar::<CF>::from(gadget));
+                }
+
+                dest_gadgets.push(NonNativeFieldVar::<F, CF>::Var(
+                    AllocatedNonNativeFieldVar::<F, CF> {
+                        cs: cs.clone(),
+                        limbs,
+                        num_of_additions_over_normal_form: CF::zero(),
+                        is_in_the_normal_form: true,
+                        target_phantom: Default::default(),
+                    },
+                ));
+            });
+
+        Ok((dest_gadgets, dest_bits))
+    }
+}
+
+impl<F: PrimeField, CF: PrimeField, PS: CryptographicSponge, S: CryptographicSpongeVar<CF, PS>>
+    CryptographicSpongeVar<CF, PS> for FiatShamirAlgebraicSpongeRngVar<F, CF, PS, S>
+{
+    type Parameters = S::Parameters;
+
+    fn new(cs: ConstraintSystemRef<CF>, params: &Self::Parameters) -> Self {
+        Self {
+            cs: cs.clone(),
+            s: S::new(cs, params),
+            f_phantom: PhantomData,
+            cf_phantom: PhantomData,
+            ps_phantom: PhantomData,
+        }
+    }
+
+    fn cs(&self) -> ConstraintSystemRef<CF> {
+        self.cs.clone()
+    }
+
+    fn absorb(&mut self, input: &impl AbsorbGadget<CF>) -> Result<(), SynthesisError> {
+        self.s.absorb(input)
+    }
+
+    fn squeeze_bytes(&mut self, num_bytes: usize) -> Result<Vec<UInt8<CF>>, SynthesisError> {
+        self.s.squeeze_bytes(num_bytes)
+    }
+
+    fn squeeze_bits(&mut self, num_bits: usize) -> Result<Vec<Boolean<CF>>, SynthesisError> {
+        self.s.squeeze_bits(num_bits)
+    }
+
+    fn squeeze_field_elements(
+        &mut self,
+        num_elements: usize,
+    ) -> Result<Vec<FpVar<CF>>, SynthesisError> {
+        self.s.squeeze_field_elements(num_elements)
+    }
+}