From f3501333b7b006a40ed12b7d22d1cf1d47dac981 Mon Sep 17 00:00:00 2001
From: Deirdre Connolly <deirdre@zfnd.org>
Date: Mon, 15 Mar 2021 02:59:08 -0400
Subject: [PATCH] Orchard: tidy

---
 zebra-chain/src/orchard/keys.rs            | 38 ++++++++++++++--------
 zebra-chain/src/orchard/note/nullifiers.rs | 12 ++++---
 2 files changed, 33 insertions(+), 17 deletions(-)

diff --git a/zebra-chain/src/orchard/keys.rs b/zebra-chain/src/orchard/keys.rs
index 4029ffdf8..250546336 100644
--- a/zebra-chain/src/orchard/keys.rs
+++ b/zebra-chain/src/orchard/keys.rs
@@ -74,7 +74,9 @@ fn prf_expand(sk: [u8; 32], t: Vec<&[u8]>) -> [u8; 64] {
 
     state.update(&sk[..]);
 
-    t.iter().map(|t_i| state.update(t_i));
+    for t_i in t {
+        state.update(t_i);
+    }
 
     *state.finalize().as_array()
 }
@@ -370,14 +372,6 @@ impl fmt::Debug for NullifierDerivingKey {
     }
 }
 
-impl From<[u8; 32]> for NullifierDerivingKey {
-    fn from(bytes: [u8; 32]) -> Self {
-        Self(pallas::Base::from_bytes(&bytes).unwrap())
-    }
-}
-
-impl Eq for NullifierDerivingKey {}
-
 impl From<NullifierDerivingKey> for [u8; 32] {
     fn from(nk: NullifierDerivingKey) -> [u8; 32] {
         nk.0.to_bytes()
@@ -390,6 +384,18 @@ impl From<&NullifierDerivingKey> for [u8; 32] {
     }
 }
 
+impl From<NullifierDerivingKey> for pallas::Base {
+    fn from(nk: NullifierDerivingKey) -> pallas::Base {
+        nk.0
+    }
+}
+
+impl From<[u8; 32]> for NullifierDerivingKey {
+    fn from(bytes: [u8; 32]) -> Self {
+        Self(pallas::Base::from_bytes(&bytes).unwrap())
+    }
+}
+
 impl From<SpendingKey> for NullifierDerivingKey {
     /// nk = ToBase^Orchard(PRF^expand_sk ([7]))
     ///
@@ -402,6 +408,8 @@ impl From<SpendingKey> for NullifierDerivingKey {
     }
 }
 
+impl Eq for NullifierDerivingKey {}
+
 impl PartialEq<[u8; 32]> for NullifierDerivingKey {
     fn eq(&self, other: &[u8; 32]) -> bool {
         <[u8; 32]>::from(*self) == *other
@@ -501,7 +509,7 @@ impl fmt::Display for IncomingViewingKey {
 
 impl From<[u8; 32]> for IncomingViewingKey {
     /// Generate an _IncomingViewingKey_ from existing bytes.
-    fn from(mut bytes: [u8; 32]) -> Self {
+    fn from(bytes: [u8; 32]) -> Self {
         Self {
             // TODO: handle setting the Network better.
             network: Network::default(),
@@ -663,9 +671,13 @@ impl FullViewingKey {
         // let K = I2LEBSP_l_sk(rivk)
         let K: [u8; 32] = self.ivk_commit_randomness.into();
 
-        let t: Vec<&[u8]> = vec![&[0x82u8]];
-        t.push(&<[u8; 32]>::from(self.spend_validating_key));
-        t.push(&<[u8; 32]>::from(self.nullifier_deriving_key));
+        let mut t: Vec<&[u8]> = vec![&[0x82u8]];
+
+        let ak_bytes = <[u8; 32]>::from(self.spend_validating_key);
+        t.push(&ak_bytes);
+
+        let nk_bytes = <[u8; 32]>::from(self.nullifier_deriving_key);
+        t.push(&nk_bytes);
 
         // let R = PRF^expand_K( [0x82] || I2LEOSP256(ak) || I2LEOSP256(nk) )
         prf_expand(K, t)
diff --git a/zebra-chain/src/orchard/note/nullifiers.rs b/zebra-chain/src/orchard/note/nullifiers.rs
index 59b307269..584e1983e 100644
--- a/zebra-chain/src/orchard/note/nullifiers.rs
+++ b/zebra-chain/src/orchard/note/nullifiers.rs
@@ -2,7 +2,7 @@
 #![allow(dead_code)]
 
 use group::GroupEncoding;
-use halo2::pasta::pallas;
+use halo2::{arithmetic::FieldExt, pasta::pallas};
 
 use super::super::{
     commitment::NoteCommitment, keys::NullifierDerivingKey, sinsemilla::*, tree::Position,
@@ -28,7 +28,7 @@ pub fn mixing_pedersen_hash(P: pallas::Point, x: pallas::Scalar) -> pallas::Poin
 /// PoseidonHash(x, y) = f([x, y, 0])_1 (using 1-based indexing).
 ///
 /// [poseidonhash]: https://zips.z.cash/protocol/nu5.pdf#poseidonhash
-fn poseidon_hash(x: pallas::Base, y: pallas::Base) -> pallas::Base {
+fn poseidon_hash(_x: pallas::Base, _y: pallas::Base) -> pallas::Base {
     unimplemented!()
 }
 
@@ -41,8 +41,12 @@ fn poseidon_hash(x: pallas::Base, y: pallas::Base) -> pallas::Base {
 ///
 /// [concreteprfs]: https://zips.z.cash/protocol/protocol.pdf#concreteprfs
 /// [poseidonhash]: https://zips.z.cash/protocol/nu5.pdf#poseidonhash
-fn prf_nf(nk: [u8; 32], rho: [u8; 32]) -> [u8; 32] {
-    poseidon_hash(nk.into(), rho.into()).into()
+fn prf_nf(nk_bytes: [u8; 32], rho_bytes: [u8; 32]) -> [u8; 32] {
+    poseidon_hash(
+        pallas::Base::from_bytes(&nk_bytes).unwrap(),
+        pallas::Base::from_bytes(&rho_bytes).unwrap(),
+    )
+    .into()
 }
 
 /// A Nullifier for Orchard transactions