Circle’s Arc Network Reveals Quantum Resistance Plans as Bitcoin, Ethereum Face Threat

Arc, an upcoming layer-1 blockchain backed by USDC stablecoin issuer Circle, announced that its impending mainnet launch will come with post-quantum signature support—part of a broader roadmap to address growing concerns about quantum computing threats to cryptocurrency.

The Ethereum Virtual Machine-compatible blockchain aims to protect institutional digital assets from future quantum attacks that could break current cryptographic systems.

The network’s roadmap spans wallets, private smart contract state, validator authentication, and supporting infrastructure. Unlike approaches that would force disruptive network-wide resets, Arc’s design is opt-in with no mandatory migration required, according to the company.

Post-quantum signature support will arrive alongside the forthcoming mainnet launch, while quantum-resistance private state protection is noted as a “near-term” enhancement. Post-quantum-designed infrastructure will come later, followed by the “long-term” improvement of validator signature hardening.

The technical challenges are significant. While classical signatures measure 64-65 bytes, post-quantum signatures can be an order of magnitude larger. Arc’s sub-second block finalization leaves attackers only a 500 millisecond window to forge validator signatures. The roadmap document emphasizes that blockchains need quantum-resistant protections across every layer of the stack, not just at the wallet level.

The move highlights challenges facing established networks—Bitcoin’s migration to post-quantum wallets alone could take months of continuous processing in a best-case scenario, Arc’s documentation states.

“The organizations that lead this transition will be the ones that started building before the urgency became undeniable,” Arc’s post reads. The technical complexity of quantum-resistant migrations poses significant hurdles for networks with large user bases and extensive infrastructure.

The quantum threat has gained urgency as “Q-Day”—when quantum computers could break public-key cryptography—approaches. The National Institute of Standards and Technology has warned about “harvest now, decrypt later” attacks, where adversaries collect encrypted data today to decrypt once quantum computers become powerful enough.

Most major blockchain networks lack adequate preparation for quantum threats that could render current security obsolete, making proactive approaches increasingly critical for protecting long-lived digital assets.

Bitcoin developers have discussed potential mitigation solutions for years, with a Bitcoin Improvement Proposal (BIP 360) recently gaining traction. Meanwhile, Ethereum developers have coalesced around a roadmap championed by co-founder Vitalik Buterin and the Ethereum Foundation, with plans to implement quantum resistance before it’s a problem.

The price of ALGO has surged over the last week after the Algorand blockchain was cited in a Google research paper about post-quantum cryptography. Google recently said that the quantum threat to Bitcoin could take root by 2032, even sooner than previously projected.