Here’s an issue that most crypto projects haven’t talked about yet. Quantum computers will eventually become powerful enough to break the cryptographic locks that protect every blockchain in existence. The company behind Circle $USDCapparently not wanting to be caught off guard.
The stablecoin giant has released a white paper outlining a step-by-step post-quantum security roadmap for its upcoming layer-1 blockchain, Arc. The plan covers everything from wallets and validators to off-chain infrastructure, with post-quantum signature support expected to be available when Arc’s mainnet goes live in 2026.
What Circle is actually building
The blockchain will incorporate NIST standard lattice-based algorithms such as ML-DSA, CRYSTALS-Dilithium, and Falcon. These are cryptographic signature schemes specifically designed to withstand attacks from quantum computers that have been vetted by the National Institute of Standards and Technology.
$USDC Serves as Arc’s native gas token. Arc’s public testnet launched in October 2025. The mainnet goal is sometime in 2026, with post-quantum signatures scheduled to go live from the first block.
The roadmap doesn’t end with the launch. Near-term plans include quantum-resistant private state and confidentiality features.
“Harvest now, decrypt later” problem
This roadmap specifically addresses “Harvest Now Decrypt Later” attacks. Attackers can now record and store encrypted data and wait until quantum computers are powerful enough to decrypt the data.
Expert estimates suggest that Q-Day, the moment when quantum computers can break current public-key cryptography, could arrive as early as 2030.
Previous research into Circle’s quantum-ready capabilities dates back to January 2026, suggesting the company had been working on the issue for several months before publishing its Arc roadmap.
Why this matters to investors
Most existing layer 1 blockchains will need to be retrofitted for quantum resistance through hard forks and protocol upgrades. Ethereum’s roadmap includes quantum resistance as a long-term goal, but it conflicts with a backlog of scaling upgrades.
Agencies that need to comply with evolving cybersecurity regulations, particularly in the United States, where NIST standards have great regulatory importance, may find Arc’s precise compliance with these standards compelling.
Post-quantum cryptographic signatures are significantly larger than traditional cryptographic signatures, which poses significant challenges in terms of block size, transaction throughput, and storage costs. Circle has not released details about how Arc plans to manage these tradeoffs at scale.
