Inside Zcash's new node that targets Visa-scale privacy at 50,000 transactions per second

Zakura is a newly released full node software for Zcash, launched independently of the Zcash Foundation, designed to improve synchronization speed and reduce storage needs. It is a pruned, fast-syncing fork of the Foundation’s Zebra node and supports compatibility with the original zcashd client, which reached end of life on July 18. Zakura incorporates support for the upcoming Ironwood (NU6.3) network upgrade scheduled to activate on July 28. Ironwood introduces a mechanism, termed the turnstile, to cap withdrawals from the Orchard shielded pool, preventing counterfeit ZEC that may have arisen from a long-standing cryptographic bug.

The development of Zakura forms part of a broader effort to scale Zcash to handle transaction volumes on par with global payment networks like Visa and Mastercard, which reportedly process over 50,000 transactions per second. Zcash’s current cryptography demands very high throughput from nodes—over 500 megabytes of data per second—to maintain such volumes, which existing software cannot support. The team behind Zakura aims to close this gap through advanced cryptographic techniques like recursive proofs, developed under Project Tachyon, which enable one proof to verify thousands of transactions, drastically reducing data verification requirements.

In addition to node improvements, wallet performance presents another bottleneck. Because Zcash transactions hide recipients, wallets must download and scan all transactions to identify those relevant to them, limiting wallet processing to about one transaction per second. Valar Group is addressing this with private information retrieval (PIR) research, which would allow wallets to fetch only their own transactions from servers without disclosing which data they requested, preserving privacy while boosting efficiency.

Ironwood’s introduction follows the discovery in late May of a critical soundness bug in Orchard—Zcash’s newest shielded pool—that permitted the creation of counterfeit coins with no on-chain trace. The bug was fixed through emergency measures and a hard fork in early June, but since zero-knowledge proofs reveal nothing beyond validity, existing counterfeit coins could not be identified or removed. Ironwood’s turnstile mechanism caps the amount leaving the shielded pool, effectively trapping counterfeit ZEC and preserving the reliability of the total coin supply. Zakura supports this upgrade and includes experimental software to propagate new blocks across the network rapidly, a necessity for handling high transaction volumes.