Circle advances blockchain Arc to resist quantum attacks; "Q-Day" may arrive before 2030

Odaily Planet Daily reports that stablecoin issuer Circle said that its upcoming Layer1 network Arc will be designed with post-quantum resilience as the core objective, and emphasized that long-term cryptographic security has become a “baseline requirement” for financial infrastructure. The “Q-Day” (the tipping point at which quantum computing can break public-key encryption) may arrive before 2030, or even earlier. At the same time, attackers have begun collecting data in advance, planning to decrypt it once quantum computing matures, and potential risks have become apparent ahead of time.

Arc’s testnet went live in October 2025, and the mainnet is expected to be launched within the year. In the initial rollout, it will support post-quantum signature schemes, allowing users to create post-quantum wallets (not mandatory). It will then be expanded to include transaction privacy protection, covering encryption handling for balances, recipients, and transaction data.

In the long run, Arc also plans to introduce post-quantum mechanisms at the level of validator node authentication and the network infrastructure layer, building a comprehensive protection system. Circle said Arc is intended to provide developers and institutions with a practical path for a smooth transition to the post-quantum era, rather than remaining at the theoretical level. (The Block)