Zakura, the team developing Zcash infrastructure, plans for post-quantum signature opcodes to land in January. The proposal centers on transparent payments, where addresses, amounts, and transaction history remain visible on the blockchain — unlike Zcash's shielded pools, which hide that data — and where most circulating ZEC is currently held.

A new engineering post describes a wallet design that combines those signatures with rotating transparent addresses and private information retrieval, known as PIR. Together, the components tackle a future cryptographic risk while addressing a privacy weakness that would otherwise appear when wallets begin using many fresh addresses.

Why exposed public keys could become a liability

Transparent Zcash addresses initially contain a hash of a public key. The public key itself becomes visible when the address spends, allowing the network to verify the payment signature. If future technology made it possible to recover a private key from that public key, any funds left at the same address, or sent there later, could face greater exposure. That is the specific weakness the proposed post-quantum signatures are meant to close.

Fresh addresses keep later funds behind a new key

Address rotation gives a wallet a way to reduce that repeated exposure. After an address spends, the wallet can move its remaining balance to a newly derived address. That new address is tied to a different public key, whose hash remains visible while the key itself stays undisclosed.

The approach does not require anyone to open a new wallet or record another recovery phrase after every payment. A standard wallet seed can derive a sequence of separate addresses and key pairs, allowing the software to create new receiving and change addresses from a single existing backup.

That separation also depends on protecting the wallet's extended public-key and viewing information. Those records can reveal more about a wallet's address structure than an ordinary transaction would, weakening the benefit of keeping each public key separate.

Wallet lookups can reveal the links the blockchain does not

Generating new addresses creates a practical problem: the wallet still needs to find incoming payments, track funds it has spent, and rebuild history after a recovery. A normal light wallet may ask a server for activity associated with address A, then B, then C. Those addresses can appear unrelated on the blockchain, but the server sees the requests arriving from the same wallet. It can therefore connect the addresses even when the public ledger alone does not provide that link.

Zakura proposes PIR to avoid that leak. The wallet retrieves the record it needs from a server without revealing which record it selected. It can also download compact public activity filters, check them locally for possible matches, and make a private request only when a block range may contain relevant history.

The three components work as follows:

• Fresh addresses keep later funds behind public keys that have not yet been revealed by an earlier spend.
• Hash-based signatures create the proposed post-quantum path for authorizing transparent payments.
• Private information retrieval lets the wallet search for its history without identifying its addresses to the server.

Transparent payment data would remain public on the Zcash blockchain. PIR narrows the extra information exposed when a wallet asks a service to monitor several addresses, preserving the purpose of rotating them in the first place.

A long-term risk, not a current emergency

The design speaks to the same concern raised in Europol's warning about exposed wallet keys. A sufficiently capable future attacker could target a public key that has appeared on-chain, making older address-reuse habits less safe than they are today.

Neither Europol nor Zakura says that a practical quantum attack is currently available. The challenge is preparing wallet software, infrastructure providers, and users before a cryptographic migration becomes urgent.

What remains visible and unchanged:

• Transparent transaction details remain public on-chain.
• Privacy still depends on wallet behavior and the services a user connects to.
• The announcement introduces no ZEC swap, wallet migration, or new recovery phrase.

Private queries arrive before the signature goal

Zakura says the PIR component is reaching its Vizor wallet first. Users can test the experimental feature by enabling "Private queries" in the wallet settings, giving the team a way to evaluate how private history retrieval works before the wider signature changes arrive.

The January milestone concerns the post-quantum signature opcodes for transparent pools. Wallets and services will still need to support the updated payment flow, so the date is a development target rather than a guarantee that every transparent Zcash wallet will receive the protection at once.

Preparing the wallet layer early

The usefulness of the plan lies in pairing stronger payment authorization with the wallet infrastructure needed to use it privately. Fresh addresses can reduce future public-key exposure, while PIR can keep the resulting address set from becoming a readable map of one user's funds.

That is the practical goal behind Zcash's January work: prepare transparent wallets for a future cryptographic threat without creating a new privacy problem in the process.

This article is for informational purposes only and does not constitute investment security, or technical advice. The January timing is a development target and may change as the work progresses.