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Circle, the issuer of the USDC stablecoin, said on Tuesday that its Arc blockchain would support post-quantum security features at launch, arguing that institutions cannot afford to delay preparation for future cryptographic threats.
The company said that quantum risks extend beyond a single future moment often referred to as “Q-Day,” when a sufficiently powerful quantum computer could break the public-key cryptography used to secure wallets, authorize transactions, and verify network participants. Even before that point, Circle said attackers could collect encrypted data now with the aim of breaking it later, exposing sensitive off-chain data, private transaction flows, and infrastructure traffic to longer-term risk.
Industry Not Yet Ready for Post-Quantum Shift
Circle said the shift to post-quantum security would require changes across the full technology stack rather than at the wallet level alone. That includes wallets, transaction signatures, validators, hardware security modules, MPC systems, smart contract authorizations, and address migration.
The company noted that most blockchains were not built with realistic migration paths for a post-quantum future and warned that waiting too long could narrow the window for upgrades, increase the risk of rushed implementation, and create broader vulnerabilities for issuers, custodians, infrastructure providers, and asset holders.
It also warned that active addresses that have already signed transactions would need to migrate before Q-Day because their public keys have already been exposed.
The signature layer would also become harder to manage, the company said, as post-quantum signatures can be significantly larger than the classical signatures used by mainstream chains today, adding pressure to validation, storage, and network performance.
Arc to Introduce Post-Quantum Security at Launch
As part of that effort, Circle said Arc’s mainnet would launch with post-quantum signature support, giving users an opt-in path to create quantum-resistant wallets from the outset without forcing migration or triggering a network-wide reset.
The company said its roadmap would then extend to private state protection, infrastructure upgrades, and validator authentication over time, adding that Arc’s privacy features are intended to be quantum-resistant at launch, while later phases will focus on broader infrastructure protections and validator signature hardening once performance testing and tooling support are in place.
Positioning Arc for Institutional Use
Circle framed the roadmap as part of a broader pitch to banks, fintechs, stablecoin issuers, tokenized asset platforms, and other enterprises that need cryptographic protections to match the lifespan of the assets they manage.
Circle said post-quantum readiness should be treated as a core infrastructure requirement rather than a distant research topic, arguing that Arc has the advantage of being designed for that transition before launch while live networks may face a more difficult migration.
A Head Start on Quantum Risk
Circle’s broader argument is that post-quantum readiness should be treated as a long-term infrastructure priority rather than a distant technical concern. By building Arc with that transition in mind before launch, the company is positioning the network as a cleaner option for institutions that need security protections to match the lifespan of the assets they manage, especially if the industry is forced to move faster than expected.
