Zcash Developers Plan Per Swap Keys to Shield ZEC Privacy From Future Quantum Computers

The team behind Zakura, a newer version of the software that runs the Zcash network, has proposed giving every ZEC swap through NEAR Intents its own viewing key. The aim is to close a small gap that a future quantum computer could use to link a user’s private payments to their wallet. No quantum machine has been shown to recover these keys today, but developers across the industry are racing to prepare.

How NEAR Intents Swaps Expose a Refund Address

NEAR Intents lets people swap tokens across blockchains. When someone trades private ZEC for USDC, the service posts one of their Zcash addresses on NEAR’s public chain so unused funds can be returned. That address stays visible even if no refund is needed. On current computers it reveals nothing, since each address carries a public key built from the wallet’s viewing key through one-way elliptic-curve math, much like the protection around bitcoin and ether wallets.

Shor’s Algorithm and Quantum Computing Risk

A large enough quantum computer running Shor’s algorithm, published in 1994, could in theory work backward from that address to the key. Last week Google said its Willow chip produced near-perfect versions of one component such an attack would need, a step toward a capable machine. Experts still see that kind of computer as years away, with no firm timeline.

Zakura Viewing Keys and Private Information Retrieval

A Zcash wallet can create many unrelated-looking addresses, but they usually share one viewing key. Cracking it from a single published address could expose every payment received, along with amounts and memos. Spending needs a separate key, so funds would stay safe. Under Zakura’s design, each swap gets its own viewing key while the spending key stays with the main account, so an attacker would only see payments tied to that one swap.

Zcash Wallet Rollout and Quantum Resistant Payments

Wallets built on Zakura’s open-source libraries, including Vizor, could add the feature within weeks, with hardware wallets following once firmware supports it. That would put the fix in users’ hands ahead of the January target Zcash developers set earlier this month for quantum-resistant payments.