Zakura’s proposal combines hash based signatures with private wallet queries while keeping transparent transactions public.
Zcash developers are targeting January for protections designed to make transparent payments resistant to quantum attacks, as concerns about AI driven cryptographic breakthroughs draw attention to wallet security.
The team plans to introduce instructions that would let the network verify hash based spending signatures, Roman Akhtariev wrote in an engineering post for Zakura. January is the team’s target, but the post does not specify a confirmed network activation date.
Hash based signatures offer another way to prove permission to spend funds. Their security relies on hashes rather than the elliptic curve mathematics used by existing wallet signatures.
The proposal follows Ethereum researcher Justin Drake’s call for the industry to prepare for “bunker mode.” Drake warned that AI driven mathematical advances could threaten existing signatures and urged holders to gradually move funds to addresses whose public keys have never been exposed.
Zakura’s plan focuses on Zcash’s transparent payments, where addresses and amounts are publicly visible. It also tackles a separate problem: checking balances can reveal which addresses belong to the same wallet.
A standard Zcash transparent address hides its public key behind a hash. Spending from the address reveals that key, which continues to control any funds left there or received later.
Moving the remaining funds to a fresh address puts them behind another public key that has not been disclosed. Akhtariev argues that this could offer additional protection if recovering private keys from exposed public keys becomes practical while hashes remain secure.
Wallets can generate fresh addresses from the same seed phrase, without requiring separate backups. Sharing an extended public key, however, can expose the public keys for multiple receiving and change addresses.
Managing those addresses creates another challenge. The wallet still needs to check for payments, track spending and recover its history. Ordinary requests give the server a readable list of addresses, allowing it to connect addresses that may otherwise appear unrelated on the blockchain.
Zakura’s tool uses private information retrieval, or PIR, to fetch records without revealing which ones the wallet requested. The wallet first checks public activity filters locally, then makes private lookups for relevant transaction histories.
The same process supports recovery from a seed phrase. It can also retrieve additional transaction details without sending the transaction ID as a readable search term.
The payments themselves remain public. PIR protects the queries used to manage them, while address rotation limits public key exposure.
Akhtariev said the transparent PIR component is coming to Vizor this week. Users can already test an experimental deployment through the wallet’s “Private queries” setting.
The January signature target concerns Zcash’s transparent pool, where addresses and transaction amounts remain public. Shielded payments, which conceal those details, rely on additional cryptographic systems that require separate safeguards against quantum attacks.
The proposed upgrade would therefore protect one part of the network rather than make all Zcash payments quantum resistant.
