Zakura Proposes Per-Swap Keys to Protect Zcash Privacy on NEAR Intents

Zakura has proposed a wallet change for Zcash (ZEC) swaps through NEAR Intents that would prevent a future quantum attacker from using one public swap address to trace an account’s incoming payments.

When a user swaps ZEC for an asset on another chain, a shielded refund address is recorded on NEAR’s public blockchain once the deposit registers. It remains there even when the swap succeeds and no refund is needed. A swap into ZEC also publishes the recipient’s shielded address.

Those addresses can appear unrelated while sharing the same incoming viewing key, which lets a wallet recognize and read payments it receives. A sufficiently powerful quantum computer could theoretically recover that key from one published address. An attacker with the key could link incoming payments and read their amounts and memos, but could not use the key alone to spend the funds.

Zakura’s design would derive a separate incoming viewing key for each swap address while keeping the account’s spending key in place. If an attacker broke one published address, the exposure would be limited to payments sent to that address rather than the account’s broader incoming payment history. The proposed wallet change would not require a Zcash network upgrade.

Using separate keys would make recovery from a wallet’s seed phrase more demanding because the restored wallet would need to find payments tied to past swaps. The proposed method records each swap index in an encrypted note in the transaction’s change output that only the wallet can read. For bridge payouts, private information retrieval would let the wallet check an address index without revealing to the server which addresses it is checking.

Zodl’s built-in ZEC swaps use NEAR Intents.

The swap-address proposal remains under review. Compatible software wallets, including Vizor, could integrate it in the coming weeks; hardware wallets would need firmware support.