A quantum computer running Shor's algorithm could theoretically recover an incoming viewing key from a publicly exposed Zcash address to link an account's wider payment history.

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Zakura developer Adam Tucker stated that a single published shielded address exposes payment histories until Project Tachyon's recursive proof upgrade deploys.

Zcash developers have targeted January 2027 for introducing post-quantum signature opcodes to protect transparent transactions.

Zcash developer Zakura proposed assigning a one-time incoming viewing key to every ZEC swap routed through NEAR Intents to protect transaction privacy against future quantum computing risks.

NEAR Intents permanently publishes a user's Zcash refund address on NEAR's public blockchain during cross-chain swaps, creating a public record even if no refund occurs.

Zakura's design uses private information retrieval to enable wallets to look up refund transactions during restoration without exposing queried addresses to database operators.

Hardware wallets will support Zakura's one-time viewing key design once their respective firmware accommodates the new key derivation process.

Zakura rejected creating separate Zcash accounts for each transaction because Keystone hardware wallets sign only from account index 0 and Ledger devices require separate approvals for each account.

Zakura's proposal limits potential quantum exposure to a single swap while keeping a wallet's main spending key unchanged, maintaining funds under a single account.

Software wallets using Zakura's open-source libraries, such as Vizor, could integrate the per-swap viewing key feature within weeks.

Zcash Open Development Lab CEO Josh Swihart stated in May 2026 that between $600 million and $700 million had flowed through Zcash's NEAR Intents route.

Shielded Labs announced project Epoch on October 1, 2026, aiming to develop post-quantum cryptography for Zcash by the end of 2027.

Zakura already uses private information retrieval for Zcash coinholder voting lookups and transparent wallet monitoring.

Coinbase published technical priorities on October 13, 2026, outlining options for Bitcoin's post-quantum migration, including staged wallet upgrades and freezing vulnerable dormant coins

A June 2026 study estimated that approximately 2.3 million Bitcoin held in lost, dormant, or early addresses cannot be moved to quantum-resistant addresses

Approximately 6.04 million to 6.26 million Bitcoin, representing over 30% of all mined Bitcoin, sit in quantum-vulnerable public key addresses

As of October 2026, Bitcoin had fallen nearly 35% from its October 2025 high, Ethereum over 50%, and Solana and XRP each 65%, partly attributed to quantum computing risks.

Almost the entire $2.9 trillion cryptocurrency market relies on classical signatures that could be compromised by sufficiently powerful quantum computers.

An estimated 6 million Bitcoin, representing over 30% of the total Bitcoin supply, is quantum-exposed at rest due to reliance on elliptic-curve signatures.

Algorand's post-quantum cryptography strategy requires delivering deployed network upgrades that institutional participants can evaluate.

Nine blockchain organizations formed the Quantum Alliance on October 15, 2026, to develop open standards for assessing quantum readiness across blockchain networks, wallets, and infrastructure.