The Zcash development team plans to allocate independent keys for each ZEC exchange to prevent quantum cracking
The Zakura team, which operates the Zcash network, released a technical article stating that they plan to allocate a unique viewing key for each ZEC exchange completed through NEAR Intents, in order to block future quantum computers from exploiting public refund addresses to piece together user payment histories. NEAR Intents supports cross-chain token exchanges, and when users exchange the privacy coin ZEC for USDC, the service will publish a Zcash address for the user on the NEAR public blockchain, which will be used to return any unused ZEC.The Zcash address contains a public key generated by the wallet's viewing key, which cannot be reverse-engineered by ordinary computers, but large quantum computers running Shor's algorithm could theoretically deduce the key from the address. Zcash wallets can generate multiple seemingly unrelated addresses, but they typically share the same viewing key. Once an attacker cracks it, they can associate all payments received by the account and read the amounts and notes. Zakura's solution allocates a unique viewing key for each exchange, while the spending key remains in the user's main account. Even if the future refund address is compromised, the attacker would only be able to see payments related to that specific exchange.This design also addresses a practical issue: wallets conducting hundreds of exchanges would generate hundreds of keys, requiring each key to scan the entire Zcash chain during backup recovery. Zakura's solution is a privately queryable database that uses private information retrieval technology, so when the wallet inquires about the refund destination, the database will not know the address being queried. Zakura claims that wallets built on its open-source library (including Vizor) will be able to add this feature in the coming weeks, and hardware wallets will follow after firmware support, ahead of the January quantum-resistant payment target set by Zcash developers this month.