Circle: Q-Day may arrive before 2030; Arc public chain provides a full-stack quantum defense solution.

CoinFeed reported on April 6th that, according to Theblock, Circle officially disclosed that its upcoming Layer 1 public chain, Arc, will natively support post-quantum signature algorithms on its mainnet. Users can create quantum-resistant wallets, which will be optional rather than mandatory. Circle warns that Q-Day may arrive before 2030, and attackers are already stealing encrypted data in advance. Long-term quantum resistance is a baseline requirement for institutions. Arc is EVM compatible, and its testnet went live in October 2025, with the mainnet expected to launch in the second half of 2026. In the medium to long term, quantum resistance will be extended to the entire stack, including privacy data and verification nodes. Circle stated that post-quantum migration to public chains like Bitcoin may take several months, and delays will lead to the risk of hasty upgrades. Arc aims to provide a non-disruptive, practical migration solution.