BroadChain has learned that on April 5, The Block reported stablecoin issuer Circle's announcement regarding its upcoming Layer 1 network, Arc. A core design objective for Arc will be quantum resistance, with Circle emphasizing that long-term cryptographic security is now a "baseline requirement" for financial infrastructure.
The so-called "Q-Day"—the point at which quantum computing could break current public-key cryptography—may arrive before 2030, or possibly even sooner. Notably, attackers are already harvesting encrypted data today, intending to decrypt it once quantum computing becomes viable, meaning these potential threats are already materializing.
The Arc testnet launched in October 2025, with the mainnet expected to go live this year. At launch, Arc will support quantum-resistant signature schemes, allowing users to create quantum-resistant wallets (though this will be optional). Future upgrades will expand privacy protections to encrypt transaction details such as balances, recipients, and other data.
Longer-term, Arc also plans to implement quantum-resistant mechanisms at the validator node authentication and network infrastructure levels, building a comprehensive defense system. Circle stated that Arc aims to provide developers and institutions with a practical, actionable pathway for transitioning into the post-quantum era—moving beyond theoretical solutions.