Zcash developers set January target for quantum-resistant payments after ‘bunker mode’ scare

What it is

Zcash's Zakura client team (engineer Roman Akhtariev) targets January for shipping post-quantum signature opcodes supporting hash-based signatures on Zcash's transparent payment pool. Separately, Zakura has built a private-information-retrieval (PIR) balance-lookup tool, now experimentally available in the Vizor wallet under the "Private queries" setting.

How it works

Hash-based signatures let the network verify a spend approval via hashes (digital fingerprints of secret data) rather than elliptic-curve math. Forging approval would require breaking those hashes, so a quantum/AI breakthrough against today's elliptic-curve keys would not automatically compromise the replacement signature scheme. Separately, a standard transparent address hides its public key behind a hash until the owner spends; moving leftover funds to a fresh address puts them behind a new, undisclosed key — but wallets normally query a server for balances across these addresses, letting the server correlate addresses that look unrelated on-chain. Zakura's PIR tool lets a database return a balance record without learning which address was queried, breaking that correlation channel while leaving the (public) transaction data itself unchanged.

Preconditions / Affected

The January opcode target covers only the transparent pool — about 11.96M of 16.98M issued ZEC (~70%), per CoinDesk's calculation from ZecStats data. Shielded payments are explicitly out of scope and require separate protection against store-now-decrypt-later attacks, where an attacker who obtains a recipient's address today could save encrypted payment records and decrypt them later after a cryptographic breakthrough; that work is still pending. No network activation date has been confirmed even for the transparent-pool opcodes — January is only the development target.

What to do

• No user-facing patch or command exists yet; opcodes are a development target, not an activated upgrade.
• Users wanting to avoid wallet-server address correlation today can enable the "Private queries" setting in the Vizor wallet, which uses the experimental PIR lookup.
• Treat shielded-pool funds as still exposed to future store-now-decrypt-later decryption risk; no mitigation is currently shipped for that threat.

Caveats

The page states no confirmed network activation date, only Zakura's internal January target for landing the opcodes. The PIR tool is explicitly experimental. The urgency framing stems from Ethereum researcher Justin Drake's "bunker mode" warning that AI could break elliptic-curve wallet math "in months, not years" in a worst case — a speculative timeline, not a demonstrated attack (the article notes no practical attack on Ethereum/Bitcoin-style wallet keys has been shown).