Defer to From/Into [u8; 32] vs Zcash(De)Serialize for sprout::NoteCommitments

zebra-chain/src/commitments/sapling.rs

@@ -38,6 +38,8 @@ impl fmt::Debug for NoteCommitment {
     }
 }
 
+impl Eq for NoteCommitment {}
+
 impl From<jubjub::ExtendedPoint> for NoteCommitment {
     fn from(extended_point: jubjub::ExtendedPoint) -> Self {
         Self(jubjub::AffinePoint::from(extended_point))
@@ -50,8 +52,6 @@ impl From<NoteCommitment> for [u8; 32] {
     }
 }
 
-impl Eq for NoteCommitment {}
-
 impl TryFrom<[u8; 32]> for NoteCommitment {
     type Error = &'static str;
 
@@ -66,19 +66,6 @@ impl TryFrom<[u8; 32]> for NoteCommitment {
     }
 }
 
-impl ZcashSerialize for NoteCommitment {
-    fn zcash_serialize<W: io::Write>(&self, mut writer: W) -> Result<(), io::Error> {
-        writer.write_all(&<[u8; 32]>::from(*self)[..])?;
-        Ok(())
-    }
-}
-
-impl ZcashDeserialize for NoteCommitment {
-    fn zcash_deserialize<R: io::Read>(mut reader: R) -> Result<Self, SerializationError> {
-        Self::try_from(reader.read_32_bytes()?).map_err(|e| SerializationError::Parse(e))
-    }
-}
-
 impl NoteCommitment {
     /// Generate a new _NoteCommitment_ and the randomness used to create it.
     ///

zebra-chain/src/commitments/sprout.rs

@@ -2,14 +2,9 @@
 
 #![allow(clippy::unit_arg)]
 
-use std::io;
-
 use sha2::{Digest, Sha256};
 
-use crate::{
-    notes::sprout::Note,
-    serialization::{ReadZcashExt, SerializationError, ZcashDeserialize, ZcashSerialize},
-};
+use crate::notes::sprout::Note;
 
 /// The randomness used in the Pedersen Hash for note commitment.
 #[derive(Copy, Clone, Debug, PartialEq)]
@@ -23,10 +18,18 @@ impl AsRef<[u8]> for CommitmentRandomness {
 }
 
 /// Note commitments for the output notes.
-#[derive(Clone, Copy, Debug)]
+#[derive(Clone, Copy, Debug, Deserialize, PartialEq, Serialize)]
 #[cfg_attr(test, derive(proptest_derive::Arbitrary))]
 pub struct NoteCommitment(pub(crate) [u8; 32]);
 
+impl Eq for NoteCommitment {}
+
+impl From<[u8; 32]> for NoteCommitment {
+    fn from(bytes: [u8; 32]) -> Self {
+        Self(bytes)
+    }
+}
+
 impl From<Note> for NoteCommitment {
     /// NoteCommit_rcm^Sprout(a_pk, v, rho)
     ///
@@ -43,15 +46,8 @@ impl From<Note> for NoteCommitment {
     }
 }
 
-impl ZcashSerialize for NoteCommitment {
-    fn zcash_serialize<W: io::Write>(&self, mut writer: W) -> Result<(), io::Error> {
-        writer.write_all(&self.0[..])?;
-        Ok(())
-    }
-}
-
-impl ZcashDeserialize for NoteCommitment {
-    fn zcash_deserialize<R: io::Read>(mut reader: R) -> Result<Self, SerializationError> {
-        Ok(Self(reader.read_32_bytes()?))
+impl From<NoteCommitment> for [u8; 32] {
+    fn from(cm: NoteCommitment) -> [u8; 32] {
+        cm.0
     }
 }

zebra-chain/src/transaction/joinsplit.rs

@@ -1,7 +1,12 @@
-use crate::types::amount::{Amount, NonNegative};
-use crate::{ed25519_zebra, notes::sprout, proofs::ZkSnarkProof};
 use serde::{Deserialize, Serialize};
 
+use crate::{
+    ed25519_zebra,
+    notes::sprout,
+    proofs::ZkSnarkProof,
+    types::amount::{Amount, NonNegative},
+};
+
 /// A _JoinSplit Description_, as described in [protocol specification §7.2][ps].
 ///
 /// [ps]: https://zips.z.cash/protocol/protocol.pdf#joinsplitencoding
@@ -23,9 +28,7 @@ pub struct JoinSplit<P: ZkSnarkProof> {
     /// A nullifier for the input notes.
     pub nullifiers: [crate::notes::sprout::Nullifier; 2],
     /// A note commitment for this output note.
-    ///
-    /// XXX refine type to [T; 2] -- there are two commitments
-    pub commitments: [[u8; 32]; 2],
+    pub commitments: [crate::commitments::sprout::NoteCommitment; 2],
     /// An X25519 public key.
     pub ephemeral_key: x25519_dalek::PublicKey,
     /// A 256-bit seed that must be chosen independently at random for each

zebra-chain/src/transaction/serialize.rs

@@ -244,8 +244,8 @@ impl<P: ZkSnarkProof> ZcashSerialize for JoinSplit<P> {
         writer.write_all(&self.anchor[..])?;
         writer.write_32_bytes(&self.nullifiers[0].into())?;
         writer.write_32_bytes(&self.nullifiers[1].into())?;
-        writer.write_all(&self.commitments[0][..])?;
-        writer.write_all(&self.commitments[1][..])?;
+        writer.write_32_bytes(&self.commitments[0].into())?;
+        writer.write_32_bytes(&self.commitments[1].into())?;
         writer.write_all(&self.ephemeral_key.as_bytes()[..])?;
         writer.write_all(&self.random_seed[..])?;
         self.vmacs[0].zcash_serialize(&mut writer)?;
@@ -267,7 +267,10 @@ impl<P: ZkSnarkProof> ZcashDeserialize for JoinSplit<P> {
                 notes::sprout::Nullifier::from(reader.read_32_bytes()?),
                 notes::sprout::Nullifier::from(reader.read_32_bytes()?),
             ],
-            commitments: [reader.read_32_bytes()?, reader.read_32_bytes()?],
+            commitments: [
+                commitments::sprout::NoteCommitment::from(reader.read_32_bytes()?),
+                commitments::sprout::NoteCommitment::from(reader.read_32_bytes()?),
+            ],
             ephemeral_key: x25519_dalek::PublicKey::from(reader.read_32_bytes()?),
             random_seed: reader.read_32_bytes()?,
             vmacs: [

zebra-chain/src/transaction/tests/arbitrary.rs

@@ -24,7 +24,7 @@ impl<P: ZkSnarkProof + Arbitrary + 'static> Arbitrary for JoinSplit<P> {
             any::<Amount<NonNegative>>(),
             array::uniform32(any::<u8>()),
             array::uniform2(any::<sprout::Nullifier>()),
-            array::uniform2(array::uniform32(any::<u8>())),
+            array::uniform2(any::<commitments::sprout::NoteCommitment>()),
             array::uniform32(any::<u8>()),
             array::uniform32(any::<u8>()),
             array::uniform2(any::<crate::types::MAC>()),