From 31ea91ced8c9d047f0c1bcb10f5076e91703bfb4 Mon Sep 17 00:00:00 2001
From: Kris Nuttycombe <kris@electriccoin.co>
Date: Tue, 8 Jun 2021 11:33:52 -0600
Subject: [PATCH] Ensure tze digest is only included if TZEs are in the
 consensus rules.

---
 zcash_primitives/src/transaction/txid.rs | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/zcash_primitives/src/transaction/txid.rs b/zcash_primitives/src/transaction/txid.rs
index 464143947..04044b17b 100644
--- a/zcash_primitives/src/transaction/txid.rs
+++ b/zcash_primitives/src/transaction/txid.rs
@@ -572,13 +572,7 @@ impl TransactionDigest<Authorized> for BlockTxCommitmentDigester {
         orchard_digest: Self::OrchardDigest,
         #[cfg(feature = "zfuture")] tze_digest: Self::TzeDigest,
     ) -> Self::Digest {
-        let digests = [
-            transparent_digest,
-            sapling_digest,
-            orchard_digest,
-            #[cfg(feature = "zfuture")]
-            tze_digest,
-        ];
+        let digests = [transparent_digest, sapling_digest, orchard_digest];
 
         let mut personal = [0; 16];
         (&mut personal[..12]).copy_from_slice(ZCASH_AUTH_PERSONALIZATION_PREFIX);
@@ -591,6 +585,11 @@ impl TransactionDigest<Authorized> for BlockTxCommitmentDigester {
             h.write_all(digest.as_bytes()).unwrap();
         }
 
+        #[cfg(feature = "zfuture")]
+        if TxVersion::suggested_for_branch(consensus_branch_id).has_tze() {
+            h.write_all(tze_digest.as_bytes()).unwrap();
+        }
+
         h.finalize()
     }
 }