Use convenience Reader/Writer methods to only use From/Into for nullifer serialization

And thus remove duplicative Zcash(De)Serialization impls

zebra-chain/src/notes/sapling/nullifiers.rs

@@ -1,12 +1,9 @@
 #![allow(clippy::unit_arg)]
 #![allow(dead_code)]
 
-use std::io;
-
 use crate::{
     commitments::sapling::{pedersen_hashes::mixing_pedersen_hash, NoteCommitment},
     keys::sapling::NullifierDerivingKey,
-    serialization::{ReadZcashExt, SerializationError, ZcashDeserialize, ZcashSerialize},
     treestate::note_commitment_tree::Position,
 };
 
@@ -29,7 +26,7 @@ fn prf_nf(nk: [u8; 32], rho: [u8; 32]) -> [u8; 32] {
 }
 
 /// A Nullifier for Sapling transactions
-#[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
+#[derive(Clone, Copy, Debug, Eq, PartialEq, Serialize, Deserialize)]
 #[cfg_attr(test, derive(proptest_derive::Arbitrary))]
 pub struct Nullifier([u8; 32]);
 
@@ -47,16 +44,8 @@ impl<'a> From<(NoteCommitment, Position, &'a NullifierDerivingKey)> for Nullifie
     }
 }
 
-impl ZcashDeserialize for Nullifier {
-    fn zcash_deserialize<R: io::Read>(mut reader: R) -> Result<Self, SerializationError> {
-        let bytes = reader.read_32_bytes()?;
-
-        Ok(Self(bytes))
-    }
-}
-
-impl ZcashSerialize for Nullifier {
-    fn zcash_serialize<W: io::Write>(&self, mut writer: W) -> Result<(), io::Error> {
-        writer.write_all(&self.0[..])
+impl From<Nullifier> for [u8; 32] {
+    fn from(n: Nullifier) -> Self {
+        n.0
     }
 }

zebra-chain/src/notes/sprout/nullifiers.rs

@@ -1,14 +1,9 @@
 #![allow(dead_code)]
 
-use std::io;
-
 use byteorder::{ByteOrder, LittleEndian};
 use serde::{Deserialize, Serialize};
 
-use crate::{
-    keys::sprout::SpendingKey,
-    serialization::{ReadZcashExt, SerializationError, ZcashDeserialize, ZcashSerialize},
-};
+use crate::keys::sprout::SpendingKey;
 
 /// PRF^nf is used to derive a Sprout nullifer from the receiver's
 /// spending key a_sk and a nullifier seed ρ, instantiated using the
@@ -63,7 +58,7 @@ impl From<NullifierSeed> for [u8; 32] {
 }
 
 /// A Nullifier for Sprout transactions
-#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
 #[cfg_attr(test, derive(proptest_derive::Arbitrary))]
 pub struct Nullifier(pub(crate) [u8; 32]);
 
@@ -84,17 +79,3 @@ impl From<Nullifier> for [u8; 32] {
         n.0
     }
 }
-
-impl ZcashDeserialize for Nullifier {
-    fn zcash_deserialize<R: io::Read>(mut reader: R) -> Result<Self, SerializationError> {
-        let bytes = reader.read_32_bytes()?;
-
-        Ok(Self(bytes))
-    }
-}
-
-impl ZcashSerialize for Nullifier {
-    fn zcash_serialize<W: io::Write>(&self, mut writer: W) -> Result<(), io::Error> {
-        writer.write_all(&self.0[..])
-    }
-}

zebra-chain/src/transaction/serialize.rs

@@ -242,8 +242,8 @@ impl<P: ZkSnarkProof> ZcashSerialize for JoinSplit<P> {
         writer.write_u64::<LittleEndian>(self.vpub_old.into())?;
         writer.write_u64::<LittleEndian>(self.vpub_new.into())?;
         writer.write_all(&self.anchor[..])?;
-        self.nullifiers[0].zcash_serialize(&mut writer)?;
-        self.nullifiers[1].zcash_serialize(&mut writer)?;
+        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_all(&self.ephemeral_key.as_bytes()[..])?;
@@ -264,8 +264,8 @@ impl<P: ZkSnarkProof> ZcashDeserialize for JoinSplit<P> {
             vpub_new: reader.read_u64::<LittleEndian>()?.try_into()?,
             anchor: reader.read_32_bytes()?,
             nullifiers: [
-                notes::sprout::Nullifier::zcash_deserialize(&mut reader)?,
-                notes::sprout::Nullifier::zcash_deserialize(&mut reader)?,
+                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()?],
             ephemeral_key: x25519_dalek::PublicKey::from(reader.read_32_bytes()?),
@@ -323,7 +323,7 @@ impl ZcashSerialize for Spend {
     fn zcash_serialize<W: io::Write>(&self, mut writer: W) -> Result<(), io::Error> {
         self.cv.zcash_serialize(&mut writer)?;
         writer.write_all(&self.anchor.0[..])?;
-        self.nullifier.zcash_serialize(&mut writer)?;
+        writer.write_32_bytes(&self.nullifier.into())?;
         writer.write_all(&<[u8; 32]>::from(self.rk)[..])?;
         self.zkproof.zcash_serialize(&mut writer)?;
         writer.write_all(&<[u8; 64]>::from(self.spend_auth_sig)[..])?;
@@ -337,7 +337,7 @@ impl ZcashDeserialize for Spend {
         Ok(Spend {
             cv: commitments::sapling::ValueCommitment::zcash_deserialize(&mut reader)?,
             anchor: SaplingNoteTreeRootHash(reader.read_32_bytes()?),
-            nullifier: notes::sapling::Nullifier::zcash_deserialize(&mut reader)?,
+            nullifier: notes::sapling::Nullifier::from(reader.read_32_bytes()?),
             rk: reader.read_32_bytes()?.into(),
             zkproof: Groth16Proof::zcash_deserialize(&mut reader)?,
             spend_auth_sig: reader.read_64_bytes()?.into(),