Do not return hash results from component hash() methods

src/plonk.rs

@@ -86,12 +86,10 @@ impl<C: CurveAffine> VerifyingKey<C> {
             .to_state();
 
         // Hash in constants in the domain which influence the proof
-        let domain_hash = &self.domain.hash(&mut hasher);
-        transcript.common_scalar(C::Scalar::from_bytes_wide(domain_hash))?;
+        self.domain.hash(&mut hasher);
 
         // Hash in `ConstraintSystem`
-        let cs_hash = &self.cs.hash(&mut hasher);
-        transcript.common_scalar(C::Scalar::from_bytes_wide(cs_hash))?;
+        self.cs.hash(&mut hasher);
 
         // Hash in vector of fixed commitments
         hasher.update(b"num_fixed_commitments");
@@ -104,7 +102,7 @@ impl<C: CurveAffine> VerifyingKey<C> {
         hasher.update(b"num_permutations");
         hasher.update(&self.permutations.len().to_le_bytes());
         for permutation in &self.permutations {
-            permutation.hash(transcript)?;
+            permutation.hash(&mut hasher, transcript)?;
         }
 
         // Hash in final Blake2bState

src/plonk/circuit.rs

@@ -3,7 +3,7 @@ use core::cmp::max;
 use core::ops::{Add, Mul};
 use ff::Field;
 use std::{
-    convert::{TryFrom, TryInto},
+    convert::TryFrom,
     ops::{Neg, Sub},
 };
 
@@ -29,9 +29,8 @@ impl<C: ColumnType> Column<C> {
         &self.column_type
     }
 
-    pub(crate) fn hash(&self, hasher: &mut Blake2bState) -> [u8; 64] {
+    pub(crate) fn hash(&self, hasher: &mut Blake2bState) {
         hasher.update(&format!("{:?}", self).as_bytes());
-        hasher.finalize().as_bytes().try_into().unwrap()
     }
 }
 
@@ -325,9 +324,8 @@ impl<F: Field> Expression<F> {
     }
 
     /// Hash an Expression into a Blake2bState
-    pub fn hash(&self, hasher: &mut Blake2bState) -> [u8; 64] {
+    pub fn hash(&self, hasher: &mut Blake2bState) {
         hasher.update(&format!("{:?}", self).as_bytes());
-        hasher.finalize().as_bytes().try_into().unwrap()
     }
 }
 
@@ -612,7 +610,7 @@ impl<F: Field> ConstraintSystem<F> {
     }
 
     /// Hashes the `ConstraintSystem` into a `u64`.
-    pub fn hash(&self, mut hasher: &mut Blake2bState) -> [u8; 64] {
+    pub fn hash(&self, mut hasher: &mut Blake2bState) {
         hasher.update(b"num_fixed_columns");
         hasher.update(&self.num_fixed_columns.to_le_bytes());
 
@@ -625,7 +623,6 @@ impl<F: Field> ConstraintSystem<F> {
         hasher.update(b"num_gates");
         hasher.update(&self.gates.len().to_le_bytes());
         for gate in self.gates.iter() {
-            hasher.update(gate.0.to_owned().as_bytes());
             gate.1.hash(&mut hasher);
         }
 
@@ -663,7 +660,7 @@ impl<F: Field> ConstraintSystem<F> {
         hasher.update(&self.lookups.len().to_le_bytes());
         for argument in self.lookups.iter() {
             hasher.update(&argument.input_columns.len().to_le_bytes());
-            hasher.update(&argument.table_columns.len().to_le_bytes());
+            assert_eq!(argument.input_columns.len(), argument.table_columns.len());
             for (input, table) in argument
                 .input_columns
                 .iter()
@@ -673,7 +670,5 @@ impl<F: Field> ConstraintSystem<F> {
                 table.hash(&mut hasher);
             }
         }
-
-        hasher.finalize().as_bytes().try_into().unwrap()
     }
 }

src/plonk/permutation.rs

@@ -11,6 +11,7 @@ pub(crate) mod keygen;
 pub(crate) mod prover;
 pub(crate) mod verifier;
 
+use blake2b_simd::State as Blake2bState;
 use std::io;
 
 /// A permutation argument.
@@ -68,7 +69,13 @@ impl<C: CurveAffine> VerifyingKey<C> {
         Ok(VerifyingKey { commitments })
     }
 
-    pub(crate) fn hash<T: Transcript<C>>(&self, transcript: &mut T) -> io::Result<()> {
+    pub(crate) fn hash<T: Transcript<C>>(
+        &self,
+        hasher: &mut Blake2bState,
+        transcript: &mut T,
+    ) -> io::Result<()> {
+        hasher.update(b"num_commitments");
+        hasher.update(&self.commitments.len().to_le_bytes());
         for commitment in &self.commitments {
             transcript.common_point(*commitment)?;
         }

src/poly.rs

@@ -6,7 +6,6 @@ use crate::arithmetic::parallelize;
 
 use blake2b_simd::State as Blake2bState;
 use ff::Field;
-use std::convert::TryInto;
 use std::fmt::Debug;
 use std::marker::PhantomData;
 use std::ops::{Add, Deref, DerefMut, Index, IndexMut, Mul, RangeFrom, RangeFull, Sub};
@@ -232,8 +231,7 @@ impl Rotation {
     }
 
     /// Hash Rotation into a Blake2bState
-    pub fn hash(&self, hasher: &mut Blake2bState) -> [u8; 64] {
+    pub fn hash(&self, hasher: &mut Blake2bState) {
         hasher.update(&format!("{:?}", self).as_bytes());
-        hasher.finalize().as_bytes().try_into().unwrap()
     }
 }

src/poly/domain.rs

@@ -380,8 +380,8 @@ impl<G: Group> EvaluationDomain<G> {
         self.quotient_poly_degree as usize
     }
 
-    /// Hashes the constants in the domain which influence the proof into a u64
-    pub fn hash(&self, hasher: &mut Blake2bState) -> [u8; 64] {
+    /// Hashes the constants in the domain which influence the proof into a Blake2bState
+    pub fn hash(&self, hasher: &mut Blake2bState) {
         hasher.update(b"k");
         hasher.update(&self.k.to_le_bytes());
 
@@ -390,7 +390,5 @@ impl<G: Group> EvaluationDomain<G> {
 
         hasher.update(b"omega");
         hasher.update(&self.omega.to_bytes());
-
-        hasher.finalize().as_bytes().try_into().unwrap()
     }
 }