Add ToConstraintField impls for some primitives

crypto-primitives/src/crh/injective_map/constraints.rs

@@ -24,8 +24,7 @@ use r1cs_std::{
     prelude::*,
 };
 
-pub trait InjectiveMapGadget<G: Group, I: InjectiveMap<G>, ConstraintF: Field, GG: GroupGadget<G, ConstraintF>>
-{
+pub trait InjectiveMapGadget<G: Group, I: InjectiveMap<G>, ConstraintF: Field, GG: GroupGadget<G, ConstraintF>> {
     type OutputGadget: EqGadget<ConstraintF>
         + ToBytesGadget<ConstraintF>
         + CondSelectGadget<ConstraintF>
@@ -75,13 +74,14 @@ where
     }
 }
 
-pub struct PedersenCRHCompressorGadget<
+pub struct PedersenCRHCompressorGadget<G, I, ConstraintF, GG, IG>
+where
     G: Group,
     I: InjectiveMap<G>,
     ConstraintF: Field,
     GG: GroupGadget<G, ConstraintF>,
     IG: InjectiveMapGadget<G, I, ConstraintF, GG>,
-> {
+{
     _compressor:        PhantomData<I>,
     _compressor_gadget: PhantomData<IG>,
     _crh:               PedersenCRHGadget<G, ConstraintF, GG>,

crypto-primitives/src/crh/pedersen/constraints.rs

@@ -1,10 +1,9 @@
-use algebra::Field;
 
 use crate::crh::{
     FixedLengthCRHGadget,
     pedersen::{PedersenCRH, PedersenParameters, PedersenWindow},
 };
-use algebra::groups::Group;
+use algebra::{Field, Group};
 use r1cs_core::{ConstraintSystem, SynthesisError};
 use r1cs_std::prelude::*;
 

crypto-primitives/src/crh/pedersen/mod.rs

@@ -7,6 +7,7 @@ use std::{
 };
 
 use crate::crh::FixedLengthCRH;
+use algebra::{Field, ToConstraintField};
 use algebra::groups::Group;
 
 
@@ -139,3 +140,11 @@ impl<G: Group> Debug for PedersenParameters<G> {
         write!(f, "}}\n")
     }
 }
+
+
+impl<ConstraintF: Field, G: Group + ToConstraintField<ConstraintF>> ToConstraintField<ConstraintF> for PedersenParameters<G> {
+    #[inline]
+    fn to_field_elements(&self) -> Result<Vec<ConstraintF>, Error> {
+        Ok(Vec::new())
+    }
+}