Circle outlines post-quantum roadmap for Arc Layer 1

Circle will launch the Arc Layer 1 mainnet later this year and will offer optional quantum-resistant wallets that use a post-quantum signature scheme. The network is EVM-compatible and its public testnet went live in October 2025.

At mainnet launch, the company will introduce a post-quantum signature scheme to allow users and institutions to create wallets designed to resist attacks by future quantum computers. Use of the feature will be optional, giving developers and firms the choice of when to migrate.

Circle outlined additional measures to expand quantum resistance beyond signatures. Arc’s privacy roadmap plans to protect confidential financial data such as balances, recipients and transaction details by avoiding plaintext exposure and wrapping public keys in an extra encryption layer.

Over the mid to long term, the company intends to harden the infrastructure around the network, including upgrades to validator authentication, to limit the risk of attackers using quantum-capable machines against critical components.

Circle warned that a break in widely used public-key cryptography, often called “Q-Day,” could arrive by 2030 or sooner and noted that attackers are already collecting encrypted data today to decrypt later when hardware improves.

The company urged institutions to begin planning for large-scale migrations. It estimated that moving all bitcoin unspent transaction outputs to post-quantum wallets could take months even if processing continued without pause, creating a risk of rushed transitions if action is delayed.

In a blog post, Circle wrote: “Circle is actively planning for these risks.” The post added, “Quantum resilience cannot live only in research papers, exploratory pilots, or distant roadmap slides. It has to show up in the infrastructure.”

Circle described Arc as offering a practical migration path that introduces post-quantum tools in working infrastructure at launch and then expands protection across the stack after rollout.

Public-key cryptography depends on mathematical problems that large quantum computers could solve much faster than classical machines. Post-quantum signature schemes use different mathematical constructions designed to resist those attacks. Blockchain projects and financial firms are studying such schemes because encrypted data captured today can be stored and decrypted later once quantum hardware becomes capable.