October 19, 2026, 1:23 a.m. EDT
3 min read
Summary
- Zakura plans to assign a distinct viewing key to each ZEC exchange conducted via NEAR Intents, restricting the transaction data that a subsequent quantum computer could extract from a publicly exposed refund address.
- This method keeps the spending keys in the possession of the users while leveraging private information retrieval to assist wallets in finding refunds without disclosing the addresses they are checking.
- Zakura indicates that supporting software wallets could integrate this open-source capability within a matter of weeks, preceding the January deadline established by Zcash developers for quantum-resistant transactions.
The developers behind Zakura, an alternative implementation of the software powering the Zcash network, aim to allocate an independent private key to every ZEC trade executed through NEAR Intents.
As detailed in a recent technical publication from the group, this modification would eliminate a vulnerability that a future quantum machine might exploit to reconstruct a user’s transaction background.
NEAR Intents is a protocol enabling cross-chain token exchanges. When a user trades confidential ZEC for USDC on the platform, the service publishes one of their secret Zcash addresses on the public NEAR blockchain to establish a destination for returning any unspent ZEC. This address becomes visible the moment a deposit is made and remains there even if the trade completes successfully without requiring a refund.
Such addresses leak no details using current computing standards. Every Zcash address incorporates a public key derived from the wallet’s viewing key—the secret utilized by a wallet to identify incoming funds—through one-way elliptic-curve mathematics comparable to the protection securing bitcoin and ether accounts.
Standard computers cannot invert this mathematical process, but an advanced quantum machine executing Shor’s algorithm, a technique introduced in 1994 specifically for that function, could theoretically reverse-engineer the address back to its original key.
This represents the active risk facing Satoshi-era bitcoin, whose public keys already reside onchain for anyone to inspect. Google recently reported that its Willow quantum processor successfully generated near-flawless iterations of a subsystem required for such an attack, marking progress toward hardware robust enough to execute it.
Quantum devices possessing such capabilities remain years away, and no definitive timeline exists for their completion, yet engineers across the sector are actively racing to deploy defenses.
One key for every swap
The architecture of Zcash introduces a distinct complication. A Zcash wallet can generate numerous addresses that appear unrelated, but they typically share a single viewing key.
An adversary who compromises this key via a single publicized address could connect every transaction the profile ever received, subsequently reading the transferred sums along with any private notes or memos attached to them.
Because executing expenditures requires a separate key, the assets themselves would remain secure. The remedy proposed by Zakura assigns a unique viewing key to each individual trade while retaining the spending key within the primary user account. Consequently, an attacker who eventually compromises a refund destination on NEAR would only observe transactions associated with that specific trade.
The proposed design also resolves a logistical challenge.
A wallet executing hundreds of trades would accumulate hundreds of keys, meaning that recovering it from a backup would necessitate scanning the entire Zcash ledger using every single one of those keys.
Zakura’s solution involves a database that wallets can query confidentially via a method known as private information retrieval. The wallet inquires about the location of its refunds, and the database responds without discovering which specific addresses the wallet queried.
To date, no quantum hardware capable of retrieving these keys has been publicly demonstrated. Zakura states that wallets developed using its open-source toolkits, such as Vizor, could integrate this functionality over the coming weeks, with hardware wallets implementing support once their respective firmware updates allow it.
This rollout would place the defense mechanism into the hands of users ahead of the January milestone previously scheduled by Zcash developers for quantum-resilient transactions earlier this month.
Read More: Zcash developers set January target for quantum-resistant payments after ‘bunker mode’ scare
Originally published at https://www.coindesk.com/tech/2026/10/19/zcash-developers-plan-a-fix-to-keep-zec-swaps-private-from-future-quantum-computers.
