The latest Zcash Arborist Call covered progress across Zebra, Zallet, Zcash Shielded Assets, Crosslink, Network Sustainability Mechanism proposals, Dynamic Fees, Ironwood formalization, and cryptographic hardening.
With Ironwood now deployed, attention continues shifting toward infrastructure improvements, protocol experiments, and strengthening the foundations for Zcash’s next upgrades.
Key Takeaways
Zebra 6.3.0 shipped with peer-scoring and security improvements, alongside experimental light-client gRPC support.
Crosslink continued improving network stability, with versions 12 and 13 released and preparations underway for the next network.
The next Crosslink Workshop is scheduled for August 26.
Zcash Shielded Assets and Asset Swaps continued progressing toward integration with recent network upgrades.
An alternative NSM proposal preserving Zcash’s existing halving schedule is being prepared.
New Dynamic Fees proposals would adjust the marginal fee and weight-ratio cap.
Ironwood formalization advanced with new work backed by Lean proofs.
A new proposal would strengthen constant-time protections across Zcash’s Rust cryptography.
🦓 Zebra 6.3.0 & Light-Client Infrastructure
Zebra 6.3.0 shipped with peer-scoring and security improvements. Zebra has also added an experimental Lightwallet-compatible gRPC server, potentially allowing light clients to connect directly to Zebra without lightwalletd in between. The feature remains disabled by default. Zebra 6.3.0 is currently the latest Zebra release listed for Ironwood infrastructure.
Transaction verification has also been separated into block and mempool verifiers, while peer banning now removes address-book entries associated with the banned IP.
Another ongoing refactor will move Zebra toward the upstream zcash_primitives transaction type, reducing duplication, while several draft PRs are exploring a new Zcash peer-to-peer protocol over QUIC.
🛠️ Zallet & Zcash Core Libraries
ZODL continued hardening Zallet following its external security audit, closing additional findings and strengthening gRPC and other wallet components.
The zcashd migration path also improved, including better handling of older key material and pre-Sapling HD seedless wallets.
Across the Rust wallet stack, final crate releases including zcash_client_sqlite 0.22 have been cut, while work continues on the pool migration engine. Zallet also gained additional RPC functionality, including signed-message support.
🛡️ Zcash Shielded Assets & Asset Swaps
QEDIT continued bringing Zcash Shielded Assets (ZSAs) up to date with recent network upgrades.
Work has largely caught up with NU6.2 across Orchard, librustzcash, Zebra, and transaction tooling, while Ironwood/NU6.3 integration continues across the remaining components.
The Orchard ZSA circuit is also being separated into its own PR for independent review, while the required Halo 2 work continues progressing.
Alongside ZSAs, private Asset Swaps are moving forward. The draft specification, ZIP 228, is now available upstream, and QEDIT is exploring how ZSAs and swaps could eventually be brought together into a more unified implementation.
⚙️ Network Sustainability Mechanism
Shielded Labs is preparing another variant of the proposed Network Sustainability Mechanism (NSM).
The draft ZIP 234 variant would preserve Zcash’s existing halving schedule, offering an alternative to the previously discussed smoothed issuance approach.
Discussion focused on making the alternatives easier for the community to understand and compare ahead of future voting.
🔗 Crosslink
Shielded Labs released Crosslink versions 12 and 13, bringing improvements to wallet performance, staking and unstaking reliability, and overall stability.
Following earlier fixes and continued monitoring, Shielded Labs reported that it is no longer observing systematic or pervasive network forking and has closed that investigation.
Attention is now shifting toward the next Crosslink network, which is expected to incorporate staking and redelegation changes, newer Zebra developments, Ironwood, and the intended 10% commission for finalizers.
Crosslink Workshop — August 26
The next Crosslink Workshop takes place August 26 at 16:00 UTC.
The session is expected to cover stability progress, hard-fork tooling, the Round 2 payment date, implementation of the next network, regular network resets, a new nightly network, and participant feedback.
Crosslink remains an active area of experimentation in the ecosystem, with the incentivized feature network continuing to attract discussion and participation.
💰 Dynamic Fees
New proposals around Zcash transaction fees were also discussed.
One draft would reduce the marginal fee from 5,000 to 1,000 zatoshis per logical action, while another is expected to explore increasing the weight-ratio cap from 4× to 10×.
The conversation also touched on how protocol experiments should be coordinated across different Zcash implementations as new ideas move from research toward potential deployment.
🔬 Ironwood Formalization
Formal verification work around Ironwood advanced with new research into group-hash indifferentiability, an important security property related to hash-derived curve points used by Zcash and Halo 2.
Backed by Lean proofs, the work aims to clearly document what has been proven, what remains unproven, and which assumptions still need to be trusted.
🔐 Constant-Time Cryptography Hardening
The call also discussed a proposal to strengthen Zcash’s Rust cryptography against timing-related information leakage.
The proposed work would identify sensitive code paths, define where constant-time behavior is required, document intentional variable-time trade-offs, and introduce tests where practical.
Discussion also suggested looking beyond librustzcash itself and examining the cryptographic dependencies it relies on.
Looking Ahead
Development continues across several layers of Zcash.
Crosslink is preparing for its next network, ZSAs and Asset Swaps continue moving toward integration, and Zebra is experimenting with a more direct path for light-client infrastructure.
At the protocol and cryptography layers, NSM and Dynamic Fees proposals, alongside Ironwood formalization and constant-time hardening, continue exploring how Zcash can evolve while strengthening its underlying security.
The next immediate milestone is the Crosslink Workshop on August 26, with these protocol discussions expected to continue in upcoming Arborist Calls.