Zcash developers plan a fix to keep ZEC swaps private from future quantum computers

What it is

Zakura, a newer version of the software that runs the Zcash network, has an engineering post proposing a separate viewing key for every ZEC swap made through NEAR Intents. The CoinDesk article of 19 October 2026 reports it. The spending key stays with the user's main account.

How it works

NEAR Intents posts one of the user's private Zcash addresses on NEAR's public chain as soon as a deposit lands, so unused ZEC can be returned. The address stays there even when the swap completes and no refund is needed.

A Zcash address carries a public key built from the wallet's viewing key. Today that is safe. A large enough quantum computer running Shor's algorithm could work backward from the address to the key. Because a wallet's addresses normally share one viewing key, cracking a single published refund address would let an attacker link every payment the account ever received. They could also read the amounts and the memos attached to them. Spending takes a separate key, so funds would not be exposed.

With one viewing key per swap, a cracked refund address would reveal only the payments tied to that swap.

The cost is key count. A wallet with hundreds of swaps would hold hundreds of keys, and restoring from backup would mean scanning the whole Zcash chain with each one. Zakura's answer is a database the wallet queries with private information retrieval. The wallet asks where its refunds landed, and the database does not learn which addresses were asked about.

Preconditions / Affected

The exposure applies to users who swap private ZEC through NEAR Intents. The attack needs a quantum computer that can recover these keys. The article says none has been demonstrated and that no one has a firm timeline for one.

What to do

Wallets built on Zakura's open-source libraries, including Vizor, could add the feature within weeks, according to Zakura. Hardware wallets would follow once their firmware supports it. The article gives no release version, command or configuration. Zakura says this would land before the January 2027 target that Zcash developers set earlier in October for quantum-resistant payments.

Caveats

The timelines are Zakura's own estimates. The article describes the design only and does not say it has shipped or been audited. It does not cover the performance or hosting of the private-retrieval database, or how it would be trusted.