Add in v6 and Ironwood TX-id / Auth-ID code by ValarDragon · Pull Request #510 · zcash/orchard

ValarDragon · 2026-06-24T17:21:47Z

This PR brings the v6 transaction hashing (txid / authorizing digest) code for Orchard and Ironwood bundles into the branch. It originated as the V6 tx-hashing work from #505 layered on the QR note-version PR (#509).

Rather than introducing a single combined struct, commitment computation is selected by two parameters threaded through the public commitment API:

BundlePoolRestrictions — the (pool, era) selector. It determines the flag-byte encoding (pre-NU6.3 rules where bit 2 is reserved, vs. NU6.3 rules where bit 2 is enableCrossAddress).
TxVersion (V5 / V6) — the transaction version the bundle is encoded in. It selects the commitment personalization strings and where the anchor is committed: a v5 transaction includes the anchor in the transaction-ID (effects) digest, while a v6 transaction includes it in the authorizing digest instead.

Both are now arguments to Bundle::commitment, Bundle::<Authorized, V>::authorizing_commitment, and the hash_bundle_txid_empty / hash_bundle_auth_empty helpers. This is required because the sighashing code definitively needs to know both the pool (for the flag byte) and the transaction version (for the personalizations and anchor placement) — neither alone is sufficient.

Internally, (pool_restrictions, tx_version) is resolved by BundlePoolRestrictions::commitment_format(tx_version) into a private BundleCommitmentFormat enum with three variants:

OrchardV5 — anchor in the txid digest; legacy personalizations.
OrchardV6 — anchor in the authorizing digest; reuses the v5 action-level personalizations and gains _v6 top-level bundle/auth strings.
IronwoodV6 — anchor in the authorizing digest; fresh _v6 personalizations throughout (Ironwood bundles exist only in v6 transactions).

Each format carries its set of BLAKE2b personalization strings. Because Bundle::commitment now depends on the pool restrictions, it returns Result<BundleCommitment, CommitmentError> and fails with CommitmentError::UnrepresentableFlags when a bundle's flags cannot be encoded under the given pool (e.g. a cross-address-restricted bundle under a pre-NU6.3 pool).

New personalization strings:

Orchard v6: ZTxIdOrchardH_v6, ZTxAuthOrchaH_v6
Ironwood v6: ZTxIdIronwd_H_v6, ZTxIdIrnActCH_v6, ZTxIdIrnActMH_v6, ZTxIdIrnActNH_v6, ZTxAuthIrnwdH_v6

All constants should match:

ZIP 229 (Ironwood transaction format)
Add Ironwood v6 transaction hash vectors zcash-test-vectors#130
- Note: these test vectors are in librustzcash only, not in Orchard

ebfull

Let's make this API nicer.

ValarDragon · 2026-06-24T23:09:48Z

Updated, agreed prior API was not good.

My recollection was some decisions were made in Orchard to not expose it to V5/V6 tx formats (which is not possible for the hashing update)

I think the new bundle pool parameters implementation is far cleaner.

ValarDragon · 2026-06-24T23:52:51Z

Addressed all comments and combined into one commit!

Co-Authored-By: Dev Ojha <dojha@berkeley.edu>

Replace the internal AnchorCommitment enum with two boolean predicates (includes_anchor_in_txid_digest / includes_anchor_in_authorizing_digest) and reword the bundle commitment documentation for clarity. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

ebfull · 2026-06-25T01:59:27Z

+    fn includes_anchor_in_txid_digest(self) -> bool {
+        matches!(self, BundleCommitmentFormat::OrchardV5)
+    }
+
+    fn includes_anchor_in_authorizing_digest(self) -> bool {
+        matches!(
+            self,
+            BundleCommitmentFormat::OrchardV6 | BundleCommitmentFormat::IronwoodV6
+        )
+    }


We could just define these in terms of each other, but I'll let someone else insist on it first.

ValarDragon · 2026-06-25T02:26:57Z

Changes look great to me! Looks way better with tx version being explicit

TalDerei

checked against ZIP 229 and generated some of my own local test vectors for redundancy against zcash/zcash-test-vectors#130.

Move the orchard pin from cab7d78 to the head of zcash/orchard#510 (dev/tx-id: the v6 / Ironwood TX-id + Auth-ID work). That branch was rebased with public-API renames, so this is a source port, not just a rev bump: - Note::new reordered to (.., version, rng); swap the two args at every call site. - RandomSeed::rcm -> rcm_v2 (the V2 derivation; qr_rcm -> rcm_v3). - NoteVersion::DEFAULT removed (it was = V2); replace with V2, except real_proof_roundtrip's real delegated note, which must be V3 (DELEGATION_NOTE_VERSION) — that test was latently red before this bump because it built a V2 note the builder rejects. The new orchard circuit Config rotates the delegation and vote-proof verifying keys (share-reveal unchanged); update both VK-fingerprint tripwires accordingly. Intentional VK rotation. Verified: cargo check --all-targets --all-features clean; 141/141 unit tests pass; all ignored delegation proving tests pass (happy_path, real_proof_roundtrip); all three VK fingerprint tripwires green.

ValarDragon force-pushed the dev/tx-id branch from 3d633cc to 91ad9d9 Compare June 24, 2026 17:22

ebfull requested changes Jun 24, 2026

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Comment thread src/bundle/commitments.rs Outdated

Comment thread src/bundle/commitments.rs Outdated

ValarDragon force-pushed the dev/tx-id branch from 74917ac to 69635a4 Compare June 24, 2026 22:41

ebfull mentioned this pull request Jun 24, 2026

Add QR note version support #509

Merged

Base automatically changed from dev/qr-note-version to feat/ironwood June 24, 2026 23:32

czarcas7ic reviewed Jun 24, 2026

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Comment thread src/bundle.rs

ValarDragon force-pushed the dev/tx-id branch from e2271c7 to 47eb451 Compare June 24, 2026 23:51