Zcash Developers Target January for Post-Quantum Signatures on Transparent Payments

Zakura, the team behind a Zcash full-node implementation, says it expects post-quantum signature opcodes to land in the protocol by January, giving the network’s transparent payment pool a hash-based fallback if elliptic-curve cryptography is broken by advances in AI or quantum computing.

The plan, detailed in an engineering post by Roman Akhtariev, combines Winternitz One-Time Signatures — a hash-based scheme standardized by NIST for post-quantum use — with mandatory address rotation after every transaction. Because a transparent address in Zcash is simply a hash of a public key, the key remains hidden until the owner spends. Rotating to a fresh address after each spend keeps the public key off-chain entirely, while the WOTS signature provides a quantum-resistant proof of authorization.

Address rotation alone creates a privacy leak: when a wallet queries a light-client server for balances across many addresses, the server can link them to the same user. Zakura addresses this with Private Information Retrieval, a cryptographic protocol that lets a wallet fetch blockchain records without revealing which addresses it is asking about. The feature is shipping this week in the Vizor wallet, where users can enable “private queries” in settings to test it.

The move is a direct response to Ethereum Foundation researcher Justin Drake’s “bunker mode” warning this week, in which he argued that AI-driven mathematical breakthroughs could break ECDSA — the signature scheme securing Bitcoin, Ethereum, and Zcash’s transparent pool — “in months, not years.” Vitalik Buterin subsequently called the timeline “plausible” within two years. Drake urged holders to calmly migrate funds to fresh addresses; Zakura’s implementation automates that rotation while adding the hash-based signature layer.

Importantly, the work covers only Zcash’s transparent pool. Shielded transactions, which use zero-knowledge proofs to hide sender, recipient, and amount, rely on different cryptographic primitives and are not addressed by this upgrade. No network activation date for the new opcodes has been confirmed; the January target refers to code availability, not consensus deployment.

The push coincides with rising institutional momentum for Zcash: a Winklevoss-linked U.S. ETF filing and Europe’s first Zcash exchange-traded product both landed in recent weeks, following a network upgrade that tripled the speed of shielded payments. Vizor wallet users can already test the PIR-enabled private queries today, while the post-quantum opcodes remain on track for January code delivery.