From 40b5a73a155311915d18294e9971b1805becb0d4 Mon Sep 17 00:00:00 2001
From: Deirdre Connolly <deirdre@zfnd.org>
Date: Wed, 5 Aug 2020 23:03:09 -0400
Subject: [PATCH] impl From<&NullifierDerivingKey>, use that to derive Sapling
 Nullifier

---
 zebra-chain/src/keys/sapling.rs             | 6 ++++++
 zebra-chain/src/notes/sapling/nullifiers.rs | 4 ++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/zebra-chain/src/keys/sapling.rs b/zebra-chain/src/keys/sapling.rs
index 9c2b89c5f..d1d922f86 100644
--- a/zebra-chain/src/keys/sapling.rs
+++ b/zebra-chain/src/keys/sapling.rs
@@ -455,6 +455,12 @@ impl From<NullifierDerivingKey> for [u8; 32] {
     }
 }
 
+impl From<&NullifierDerivingKey> for [u8; 32] {
+    fn from(nk: &NullifierDerivingKey) -> [u8; 32] {
+        nk.0.to_bytes()
+    }
+}
+
 impl From<ProofAuthorizingKey> for NullifierDerivingKey {
     /// Requires JubJub's _FindGroupHash^J("Zcash_H_", "")_, then uses
     /// the resulting generator point to scalar multiply the
diff --git a/zebra-chain/src/notes/sapling/nullifiers.rs b/zebra-chain/src/notes/sapling/nullifiers.rs
index 2c2752469..836ec712c 100644
--- a/zebra-chain/src/notes/sapling/nullifiers.rs
+++ b/zebra-chain/src/notes/sapling/nullifiers.rs
@@ -39,8 +39,8 @@ impl From<[u8; 32]> for Nullifier {
     }
 }
 
-impl From<(NoteCommitment, Position, NullifierDerivingKey)> for Nullifier {
-    fn from((cm, pos, nk): (NoteCommitment, Position, NullifierDerivingKey)) -> Self {
+impl<'a> From<&'a (NoteCommitment, Position, NullifierDerivingKey)> for Nullifier {
+    fn from((cm, pos, nk): &'a (NoteCommitment, Position, NullifierDerivingKey)) -> Self {
         let rho = jubjub::AffinePoint::from(mixing_pedersen_hash(cm.0.into(), pos.0.into()));
 
         Nullifier(prf_nf(nk.into(), rho.to_bytes()))