Will These Five Upgrades Determine the Future of ZEC?

The Zcash NU7 upgrade is set to launch this week, reducing the block time from 75 seconds to 25 seconds.

Written by: William M. Peaster, Bankless

Compiled by: Chopper, Foresight News

Scaling has always been the ultimate challenge for privacy public chains. For the Zcash community, the good news is that the project developers have come up with a plan to scale ZEC privacy transactions. More importantly, the first step on this path is set to be implemented this week.

In the latest episode of Bankless titled "The Complete Roadmap for Zcash," Zcash co-founder Sean Bowe and protocol contributor Dev Ojha introduced a pathway to David Hoffman: pushing Zcash's current throughput of about 60KB per second towards Ojha's long-term goal of 50,000 transactions per second, which translates to 100MB per second, an increase of up to 1665 times.

This article will outline the five core upgrades supporting this vision.

Shortening Block Time

As early as when the NU7 upgrade date was finalized in September, I mentioned that Zcash's ninth mainnet upgrade, NU7, would reduce the block time from 75 seconds to 25 seconds. The activation height for NU7 is expected to go live on the night of November 5 to 6 UTC.

Since the block size remains unchanged, Dev Ojha calculated that this change would increase the overall chain bandwidth by about three times, reaching 180KB per second. On this basis, he also mentioned optimization methods already used by other public chains: erasure coding (splitting blocks into redundant shards so that nodes do not need to download all data to reconstruct blocks) and a more efficient message broadcasting mechanism between nodes.

It is worth noting that while Zcash is doing all this, it still adheres to proof-of-work (PoW) consensus. Ojha positions it as an attempt to create a high-throughput PoW public chain for the first time. However, there is a peculiar phenomenon to pay attention to: mining itself is random, and with an average block time of 25 seconds, about 1% of blocks can be mined in just 250 milliseconds, while another 1% may take over 110 seconds.

Upgrade Progress: The fast block feature will go live with NU7 this week. The more challenging throughput optimization work is planned to be advanced in the "next two years."

PIR Privacy Retrieval Wallet

In Ojha's words: the hardest question is how do you know you received a transfer?

Zcash's shielded addresses provide strong privacy, making it impossible for outsiders to see who transferred money to whom, which also means wallets cannot directly query their balances from servers. In the past, Zcash wallets downloaded all transactions on the chain and filtered out their own records; once the chain's throughput reaches 100MB per second, this method will be completely unfeasible.

PIR (Private Information Retrieval) is the corresponding solution. Under this mechanism, your wallet sends encrypted queries to the server storing data on the chain. Relying on homomorphic encryption technology, the server returns the query results without ever knowing the content of your query.

Interestingly, the development of AI has made this solution feasible. Ojha explains that PIR is essentially large-scale matrix-vector operations, and the AI wave has made it fast and cheap to run such computations on GPUs.

David Hoffman also raised a natural concern: initiating a query to the server, does that mean introducing a trusted intermediary? Ojha explained that the operation mode of PIR is similar to Ethereum's RPC nodes: anyone can deploy node service providers, and wallets can switch freely between multiple providers.

Upgrade Progress: Already in practical use. Bowe mentioned that a recent vote among Zcash holders utilized PIR, which he believes is the first implementation in the crypto industry.

Tachyon Proof Aggregation

Tachyon is a cryptographic reconstruction project led by Bowe, specifically addressing two major performance bottlenecks. The first bottleneck is zero-knowledge proofs: currently, full nodes need to verify each shielded transaction's ZK proof one by one.

To solve this problem, Tachyon is developing recursive SNARKs—proofs that can verify other proofs, aggregating a large number of proofs. After the modification, full nodes will not need to verify a bunch of independent proofs sequentially; they will only need to occasionally verify a single aggregated zero-knowledge proof.

Once this solution is online, it can immediately bring at least a 5-fold increase in capacity. This idea sounds familiar; David likened Tachyon's proof solution to Ethereum's ZK Rollup transaction packaging logic, and Ojha also acknowledged the value of Ethereum's exploration of recursive proofs in a production environment.

Upgrade Progress: Under development. The Tachyon code has been integrated into the cryptographic underlying stack of the Zakura full node, but it has not yet been activated on the mainnet, and the launch date has not been announced.

Stateless Chain

The second challenge for Tachyon is to solve the state bloat problem. Every time a shielded ZEC is spent, the network records a null value to prevent the same asset from being double-spent. Transparent public chains can clean up old historical data, but privacy chains must continuously maintain an ever-growing list of null values.

Tachyon plans to compress this state data. According to Ojha's vision, full nodes only need to retain the active state of the last month; older historical data can be queried in a trustless manner when needed. Bowe stated that this technology originates from a paper he co-authored with cryptographer Ian Miers.

Ojha also plainly stated that even if the goal of 50,000 TPS is achieved, it will not be possible to run nodes on low-performance devices like Raspberry Pi; however, at that throughput, nodes will only need a few hundred GB of storage space instead of PB levels.

Upgrade Progress: Developed synchronously as part of the Tachyon project.

Privacy RPC Subscription Service

The last upgrade leans more towards economic model design and is still in the conceptual stage among the five proposals.

In the Ethereum or Solana ecosystem, wallet providers like MetaMask and Phantom bear the costs of RPC servers, partly because they can monetize from users. However, Zcash does not track users, and currently, only a few service providers offer RPC data services for free.

To avoid the ecosystem "solely relying on altruism to operate," Ojha proposed a privacy subscription model: users pay in advance, for example, purchasing a quota of 1,000 queries per month; the wallet converts the quota into one-time vouchers, with each query consuming one voucher, reusing Zcash's cryptographic mechanism to prevent double spending.

In this model, service providers can verify whether the subscription voucher is valid but cannot know which user initiated the query.

Upgrade Progress: Currently only at the conceptual stage, but Ojha believes this issue can be completely resolved.

Future Outlook

Bowe explained the current significance of this scaling roadmap: AI technology allows people to easily track user identities on transparent ledgers. In addition to privacy scaling, this episode of the roadmap program also explored Zcash's post-quantum cryptography solutions, formal verification, and governance issues.