The Zakura team will add post-quantum signature opcodes for transactions to the Zcash protocol in January 2027. This measure will primarily affect the transparent pool, which holds 11.96 million out of 16.98 million ZEC (about 70%).

Transparent addresses are vulnerable when public keys are revealed

The initiative addresses risks for transparent addresses: they contain a hash of the public key, which is revealed when funds are spent. If it becomes possible to recover the private key from the public key, this vulnerability would affect already exposed addresses.

Signatures by hash and address rotation

The updated software will generate signatures that the network verifies using hashes—a different method to confirm the right to spend funds. Developers are also proposing address rotation: after spending, the remaining balance is sent to a new address to reduce the risk of key exposure.

PIR hides addresses in wallet queries

A separate issue is the privacy of queries to infrastructure. If a wallet requests history for multiple transparent addresses in plain text, the server can link them to a single user. As a solution, Zakura is developing a Private Information Retrieval mechanism, allowing users to obtain the necessary records without revealing which addresses the wallet is checking. Transparent transactions remain public. An experimental version is already available in the Vizor wallet.

Protection for transparent and shielded pools and industry context

Since about 70% of coins are in the transparent pool, the post-quantum plan primarily concerns the public part of the network; shielded transfers will require separate protection against future risks. Discussion of these threats intensified after Ethereum researcher Justin Drake called for the industry to prepare for a "bunker mode" due to potential ECDSA vulnerabilities even before sufficiently powerful quantum computers appear. Previously, the Ethereum Foundation presented a roadmap to protect the network from quantum computers, with completion targeted for 2029, and in June, EF project lead Kohaku Nicolas Consigny proposed a SPHINCS- post-quantum account protection scheme that does not require a hard fork.