Arc is purpose-built to run stablecoin payments and settlement. Unlike general-purpose blockchains where transaction fees are paid in a volatile native token, Arc uses USDC as its gas token, meaning fees are denominated in dollars from the start. The network is EVM-compatible, so developers who already write smart contracts in Solidity can build on Arc without learning a new programming environment. Circle has committed to releasing the core software under an open-source licence.

At mainnet launch, users will be able to create wallets secured by post-quantum signature schemes rather than the standard elliptic curve cryptography used by Bitcoin, Ethereum, and most other networks today. The feature is opt-in initially. Circle has outlined a four-phase roadmap that extends beyond launch: near-term phases will apply quantum-resistant cryptography to private balances and confidential payment data; mid-term work will harden cloud servers, hardware security modules (HSMs), and encrypted inter-node communications; and a final phase will address validator authentication, pending performance testing.

Why the Urgency

The concern behind this roadmap is practical, not theoretical. Current blockchains rely on elliptic curve digital signature algorithms, which are mathematically vulnerable to Shor's algorithm. A sufficiently powerful quantum computer could use that weakness to derive a wallet's private key from its publicly visible public key, allowing an attacker to drain funds. Once any transaction has been signed and broadcast, the public key sits on-chain permanently. As Circle has noted: "Active addresses that have already signed transactions must migrate before Q-Day because their public keys have been exposed."

This creates a specific category of risk known as a "harvest now, decrypt later" attack: adversaries can collect and store blockchain data today, then decrypt it years from now when quantum hardware has matured. Updated estimates reported by technology researchers suggest that breaking the 256-bit Elliptic Curve Discrete Logarithm Problem (ECDLP) could become feasible with fewer than 500,000 physical qubits. Several researchers place that threshold at 2030 or sooner, though Ark Invest assessed in March 2026 that the threat to Bitcoin remains long-term rather than immediate.

Retrofitting existing blockchains with quantum resistance is a significant obstacle. Migrating all Bitcoin UTXOs to quantum-safe alternatives alone has been estimated to require months of continuous processing alongside seven or more years of coordinated community effort, according to BIP-360, a published proposal addressing this challenge. Circle's position is that building post-quantum cryptography into Arc from protocol genesis avoids this problem entirely, though the company acknowledges that post-quantum signatures carry a real computational cost: they can be up to ten times larger than classical signatures of 64 to 65 bytes, creating validation and storage overhead that must be managed carefully.

"Quantum resilience cannot live only in research papers, exploratory pilots, or distant roadmap slides," Circle stated in Arc's official blog. "It has to show up in the infrastructure."

The Regulatory Backdrop

The US National Institute of Standards and Technology finalized its first three post-quantum cryptography standards in August 2024, including ML-DSA, a lattice-based signature algorithm directly applicable to blockchain signing. A fourth standard, HQC, was selected for standardisation in March 2025, reflecting the continued expansion of the approved algorithm set. NIST guidelines, documented in NIST IR 8547, target full deprecation of quantum-vulnerable algorithms from federal systems by 2035.

Arc is not entering an empty competitive field. Algorand is currently ranked the most quantum-ready major blockchain, giving it a benchmark position against which Arc's built-in post-quantum infrastructure will be assessed by developers and institutions evaluating long-term platform risk.

What This Means for African and South Asian Users

The stakes for users outside the United States are particularly high. Nigeria has the world's highest stablecoin adoption rate, with roughly 11.9% of the population using stablecoins and 48% of those users holding USDC specifically.

Across sub-Saharan Africa, stablecoin volumes grew more than 180% year-on-year, driven by practical applications: savings in dollar-denominated assets, cross-border remittances, and business-to-business trade settlement. Regulatory frameworks in Kenya, Nigeria, and South Africa are advancing to accommodate licensed providers.

In South Asia, India leads the 2026 Global Crypto Adoption Index. The region recorded $300 billion in crypto inflows during the first half of 2025, an 80% increase year-on-year. India's remittance economy exceeds $125 billion annually, and stablecoin corridors connecting the subcontinent to Gulf Cooperation Council (GCC) states and Southeast Asia are growing rapidly. Pakistan has also emerged as a significant actor in regional regulatory development: the country established its Pakistan Crypto Council in March 2025, marking a step toward institutional engagement with digital assets across the subcontinent.

For users and developers in these markets, the quantum risk is not abstract. Savings wallets and remittance accounts are long-duration holdings, precisely the type of asset most exposed to harvest-now-decrypt-later scenarios. Developers in Lagos, Nairobi, Johannesburg, or Mumbai building payment infrastructure on USDC rails now face a choice about which underlying chain to trust over a multi-year horizon.

Where Arc Stands

Arc's public testnet launched on October 28, 2025, with more than 100 companies participating, including BlackRock, Visa, AWS, MetaMask, Ledger, Alchemy, Chainlink, and Anthropic.

The network uses the Malachite consensus engine, developed by Informal Systems, whose team has since joined Circle. Block finality is under 500 milliseconds.

USDC's circulating supply currently stands at approximately $77.5 billion, up 78% over the past year. Together, USDC and USDT account for more than 95% of the stablecoin market, underscoring the scale of infrastructure that quantum-resistant design would need to protect over the long run.

Circle CEO Jeremy Allaire stated in November 2025 that Arc represents "significant revenue potential" over time. He has also framed the network's broader ambition in terms of its platform model: "Arc provides an opportunity for all companies to build services atop enterprise-grade network infrastructure."

The company is exploring whether Arc will eventually have a native token but has made no formal commitment. Mainnet launch is targeted for 2026.