Zcash developer Zakura proposes a fix to prevent quantum computers from linking shielded transactions via published addresses.
Tech & Launches ·
Zakura, an engineer working on Zcash full node software, has introduced a mechanism to defend against potential quantum computers that could decrypt private payments within the network's shielded pool. The proposal centers on generating isolated viewing keys for each address that must be made public, preventing a quantum attacker from connecting multiple transactions even if they compromise a single published address. The solution requires no modification to Zcash's base protocol.
The urgency stems from a specific vulnerability in cross-chain swaps. When users execute transactions through NEAR Intents—a service that has facilitated between $600 million and $700 million in ZEC transfers—their shielded addresses are recorded on NEAR's transparent blockchain as refund addresses. Although these addresses appear distinct, they all link to the same underlying key; a quantum computer running Shor's algorithm could theoretically extract that key from one published address and use it to decrypt and correlate all historical payments.
Zakura's approach isolates each posted address's incoming viewing key while preserving the wallet's core spending key, meaning a quantum compromise of any single swap address would expose only transactions tied to that address. Wallets built on Zakura's open libraries, including Vizor, can integrate this feature within weeks. The proposal arrives as part of a broader quantum-safety roadmap for Zcash, with full post-quantum privacy targeted for delivery within 12 to 18 months.