Zcash Developer Zakura Proposes Fix to Stop Quantum Computers Linking Shielded Swaps

In brief

• Zcash full node developer Zakura has proposed "one-time" viewing keys to stop a future quantum computer from linking a user's shielded Zcash payments.
• The fix targets swaps through NEAR Intents, in which the user’s shielded address is posted on NEAR’s public chain.
• Wallets built on Zakura's open-source libraries, such as Vizor, will be able to add the feature in the coming weeks, with hardware wallets to follow.

Zakura, a developer of Zcash full node software, has proposed a way to stop a future quantum computer from linking users' private Zcash payments, in an engineering post by Zakura developer Adam Tucker announced on Sunday.

The approach needs no network upgrade, Zakura said in a tweet introducing what it called "post-quantum unlinkable swaps for Zcash."

Zcash's shielded transactions hide the sender, recipient and amount. Each shielded account has a single incoming viewing key behind all of its addresses, which its wallet uses to find and decrypt payments sent to any of them.

A classical computer cannot recover that key from an address. But a sufficiently powerful quantum computer running Shor's algorithm could, according to the post, and would then be able to see the value and memo of every payment the account has received and tie them together.