Zcash developers have set January 2027 as the target for quantum-resistant signatures on transparent payments, with no activation date.
Developers of privacy-focused cryptocurrency Zcash (ZEC) plan to introduce protections designed to withstand quantum computers within months, as warnings about AI-assisted attacks draw attention to the security of crypto wallets. Roman Akhtariev, an engineer at Zakura, wrote in an engineering post for Zakura, one of the programs used to run the Zcash network and validate its transactions, that the team plans for post-quantum signature opcodes to land in Zcash in January. These instructions would allow the network to check hash-based signatures, a payment approval method designed to resist quantum attacks, although no confirmed network activation date has been given.
Protecting transparent funds
A wallet uses a secret key to approve spending and a corresponding public key that lets the network verify the approval. Deriving the secret key from the public key is meant to require an impractical amount of computing power, but Ethereum researcher Justin Drake has warned that a breakthrough could make this affordable, urging holders to prepare for a so-called ‘bunker mode’. The Zcash upgrade aims to prevent attackers from using public keys to forge a wallet owner’s approval. Hash-based signatures are checked using hashes, digital fingerprints derived from secret data, so a breakthrough against current wallet keys would not automatically defeat the replacement.
Zcash supports shielded payments, which conceal the sender, recipient, and amount, and transparent payments, which work much like Bitcoin, with addresses and amounts visible on the blockchain. According to ZecStats data, about 11.96 million of the 16.98 million ZEC issued, roughly seven in ten coins, sat in the transparent pool, and the January plan focuses on this side of the network. A standard transparent address hides its public key behind a hash until the funds are spent, and moving leftover funds to a fresh address places them behind an undisclosed key. The proposed signatures are intended to protect the payment once spending makes its approval public.
Privacy trade-offs and remaining work
Using fresh addresses can create a separate privacy risk. A user spreading savings across multiple addresses still needs to check their balances, and a typical wallet requests these records from a server, which can then link addresses that appear unrelated on the blockchain. Zakura’s lookup tool addresses this using private information retrieval, which allows a database to return a record without learning which one was requested. An experimental version is available through the ‘Private queries’ setting in Vizor, a Zcash wallet.
Shielded payments require separate work, as Zcash’s quantum recovery design warns that an attacker who obtains a recipient’s address could store encrypted payment records and attempt to decrypt them after a future breakthrough. Drake’s warning that AI could find a shortcut through the mathematics protecting Bitcoin and Ether wallets within months in the worst case weighed on the market, with ZEC trading at around USD 1,185, down about 11% over the preceding week. Ethereum’s broader migration to quantum-resistant cryptography targets December 2029, and no practical attack on these wallet keys has been demonstrated so far.
