Zcash New Node Zakura Launches, Aims to Match Visa and Mastercard's 50,000 TPS

The people rebuilding Zcash have a vision: to achieve the transaction throughput of global payment giants like Visa and Mastercard—tens of thousands of transactions per second—while maintaining full verifiability and strong privacy guarantees.

The first piece of this puzzle is Zakura, a new full-node software that released version 1.0.0 on Wednesday. It is maintained by Sean Bowe, a founding member of Zcash’s zero-knowledge cryptography team, and Dev Ojha, co-founder of Osmosis and current head of Valar Group. Both teams are funded by private ZEC donations, not by corporations or foundations.

A full node is a program that maintains a complete copy of the blockchain—in this case, the Zcash ledger—and independently verifies that each transaction complies with network rules. Zakura is a fork of Zebra, the Zcash Foundation’s node software—meaning it has been rebuilt starting from the Foundation’s official code.

Consensus rules are the shared set of guidelines that each node executes to determine which blocks and transactions are considered valid by the entire network. If a node applies different rules, it will fork and stop following the same chain as the other nodes.

Zakura also supports pruning, which removes outdated blockchain data no longer needed by nodes, significantly reducing disk usage. This compresses the chain to a small enough size that the team has released pre-processed copies—approximately 11 GB after stripping old data—allowing new nodes to download them directly instead of fetching the full history block by block from other nodes.

This allows nodes to go from zero to running in less than two minutes, with the team calling it "680 times faster."

Compatibility mode further replicates the interface of the original zcashd client, whose lifecycle ends on July 18, allowing wallets and exchange integrations built for it to continue functioning as usual.

The reason for building all of this is an arithmetic problem.

Mastercard and Visa process over 50,000 transactions per second, and the team describes this figure as "a baseline, not a goal." Zcash’s current cryptographic scheme requires nodes to receive and verify over 500 MB of data per second to keep up, as each privacy-preserving transaction carries a large proof.

This is roughly equivalent to receiving a full DVD's worth of data every 10 seconds—a level no current Zcash software can come close to achieving. But the key is understanding why each bottleneck exists.

Bowe's Tachyon project is addressing this issue through recursive proofs, where a single proof can verify the validity of thousands of other proofs, significantly reducing the amount of data that must be checked at the consensus layer.

Under the Tachyon scheme, nodes verify a single proof instead of thousands, and the team claims this reduces consensus data requirements from 100 MB per second to 500 MB, which they believe is technically achievable through careful engineering.

Wallets face different challenges. Because Zcash hides the recipient of transactions, a wallet cannot ask the server which transactions belong to it without revealing its identity. It must download all data and test each transaction individually, which is why wallet software can process at most about one transaction per second.

To eliminate this bottleneck, Valar Group is researching private information retrieval technology that allows wallets to retrieve their data from servers without revealing which entries they are requesting.

Fast block propagation means broadcasting newly mined blocks across the blockchain network as quickly as possible. Zakura is the software layer responsible for this task.

It must transmit new blocks between nodes quickly enough to enable substantial proof and wallet traffic. It includes an experimental system designed to deliver each block to every node within half a second, currently disabled by default.

The upcoming test for these ideas will arrive in late July. Ironwood, officially known as NU6.3, will activate at mainnet block 3,428,143, approximately July 28 at 8:00 AM Eastern Time, and has been supported by Zakura since its release.

Bowe stated on July 10 that all major organizations committed to this highly anticipated upgrade, which was delayed by one week due to requests from exchanges and wallet providers for additional preparation time.

Ironwood exists due to a vulnerability that nearly destroyed Zcash in June. The shielded pool, the network's privacy component, hides amounts and participants, with zero-knowledge proofs serving as cryptographic evidence of the computations.

On May 29, Shielded Labs researcher Taylor Hornby discovered a soundness vulnerability in Orchard’s proof circuit, the latest shielded pool, which allowed attackers to forge ZEC on-chain without a trace. This vulnerability had existed since Orchard was activated in May 2022.

Developers disabled Orchard via an emergency response completed on June 2, and then restored it with a corrected circuit through the NU6.2 hard fork at block 3,364,600 on June 3.

A patch cannot undo the four years during which the vulnerability was open. Zero-knowledge proofs reveal no information beyond the fact that verification succeeded, so there is no record on-chain of the contents of any Orchard transaction, and no one can prove that fake ZEC was never created.

Ironwood was built specifically to address this issue. The so-called "turnstile" at the pool's boundary restricts what can enter and exit by leveraging the fact that the amounts of ZEC entering and leaving the shielded pool are public, even though transactions within the pool remain private. By closing off Orchard to new deposits, the turnstile becomes the only exit, trapping any counterfeit funds that may be inside.

In simple terms, honest balances can be withdrawn over time, while counterfeit tokens may be prevented from exiting entirely and entering circulation. This setup traps any attempts at oversupply at the boundary, restoring reliability to the token supply.

Author: Coindesk; Translated by Shenchao TechFlow