Zcash: Securing Keys Against AI and Quantum Threats

Zcash Developers Unveil Quantum-Resistant Plan for Transparent Transactions

While much of the cryptocurrency community remains in a state of cautious deliberation, a team of Zcash developers has announced a concrete plan to address future cryptographic threats. Zakura, a company developing a Zcash full node, anticipates the integration of post-quantum signature opcodes into the Zcash network as early as January. These opcodes are fundamental instructions that will enable the network to validate a new class of digital signatures.

The stated objective, as detailed in an engineering post by Roman Akhtariev, is to achieve “full post-quantum safe transparent pools with hash based signatures.”

Zcash offers two distinct transaction types: shielded payments, which obscure the sender, recipient, and transaction amount, and transparent payments, which are publicly verifiable, similar to those on the Bitcoin network. A transparent address comprises a hash of a public key, which remains concealed until the owner initiates a transaction and reveals the key on the blockchain.

Zakura’s strategy employs a dual-layered defense. Wallets will be designed to adopt a new address after each transaction, thereby keeping public keys from being exposed. This will be complemented by the addition of a hash-based backup signature known as WOTS. Hash-based cryptographic schemes are designed to circumvent the elliptic-curve mathematics that experts fear could eventually be compromised by artificial intelligence or quantum computing.

However, the practice of rotating addresses introduces a potential privacy challenge. When a wallet requests a server to check balances across multiple addresses, the server can infer that these addresses belong to the same user. Zakura claims to mitigate this issue through private information retrieval (PIR), a cryptographic technique that allows a wallet to retrieve specific data without disclosing which records it is querying. This feature is set to be rolled out this week within the Vizor wallet, where users can already test it by enabling “private queries” in the settings.

“While others are worrying about the viability of rotating transparent addresses, we’re already solving linkability,” Zakura stated on the social media platform X.

This statement appears to be a direct response to Ethereum Foundation researcher Justin Drake, who recently advised cryptocurrency holders to calmly transfer their funds to new addresses. The public reaction to Drake’s call to action, however, was notably less composed.

Drake had previously warned that advancements in AI-driven mathematics could compromise the ECDSA signatures that secure Bitcoin and Ethereum even before quantum computers become a threat, potentially occurring “in the worst case in months not years.” Ethereum co-founder Vitalik Buterin has since commented on the discussion, expressing his belief that it is “plausible” that AI-driven mathematical breakthroughs could break encryption within the next two years.

The Zakura plan currently addresses only the transparent aspects of Zcash. The company’s post did not specify the timeline or method for activating the new opcodes across the broader network.

This development occurs as Zcash garners increasing interest from institutional investors, evidenced by a proposed U.S. ETF linked to the Winklevoss twins and Europe’s first Zcash ETP. It also follows a recent network upgrade aimed at accelerating private payment processing by a factor of three.