Dragoș Rotaru

Since we started the project, I’ve been telling the @circle team that this will be the last privacy solution in blockchain space. And we delivered. What we have built is not just privacy-preserving smart contracts. Instead, it's a paradigm shift in how blockchains, composability, and privacy need to co-exist. The design addresses the two core failures of prior privacy systems: lack of composability and a painful developer journey. Pure cryptographic privacy is elegant, but expensive and hard to scale in practice. Instead, this design builds on the now-established trend of cryptographic enclave technologies. What we’ve built is a parallel execution environment on @arc : Arc public blockchain continues processing cleartext blocks, while the Arc privacy sector operates as a parallel privacy-preserving virtual machine that processes encrypted transactions. State, transactions, and user accounts remain hidden. Validators cannot inspect what’s inside, even if they try to snoop or are compromised. Yet they continue producing blocks for both public and private states in sync, committing to each state tree. That is also a major difference from designs that rely on access control, which inevitably creates failure points and data exposure risk. The public and private state composition is the game changer for developing. For the first time, users can move between private and public state within the same block space. No bridge. No extra wallet layer. No separate accounts. A single transaction can move between private and public execution with zero friction. Furthermore, the environment gives users post-quantum protection by design. Transactions and accounts remain encrypted, and public keys stay protected under post-quantum secure algorithms. Any account or asset created inside the privacy sector is automatically post-quantum secure. The result: a fully composable privacy sector on @arc that is post-quantum secure and seamlessly interoperable with public execution. This is the last privacy layer in Web3. See the whitepaper: 6778953.fs1.hubspotuserconte… @circle @arc

Post-quantum migration is a nightmare. That's why @circle is building @arc with post-quantum protections from day one. TLDR: * Native post-quantum signature verification: Arc ships with an SLH-DSA-SHA2-128s precompile, enabling smart accounts to verify quantum-safe signatures on-chain today. * Post-quantum account abstraction: Developers can build ERC-4337 wallets that use post-quantum signatures immediately, without waiting for protocol-level transaction signature changes. * Quantum-safe privacy by default: Arc’s privacy layer encrypts transactions, state, and execution using hybrid post-quantum cryptography (X-Wing, ML-KEM, PQ TLS), protecting against harvest-now-decrypt-later attacks. * Post-quantum encrypted messaging: Transaction memos support HPKE + X-Wing encryption, giving developers a standardized way to exchange quantum-safe encrypted data on-chain. * Migration tools for existing assets: Arc introduces mechanisms such as PQ public-key registries, hash-and-rotate wallets, smart-account upgrades, and a proposed post-quantum replacement for ecrecover to help existing contracts and users migrate safely. Read more: 6778953.fs1.hubspotuserconte…

For the last 30 years we were always 5 years away from Quantum Computers. But sentiment suddenly flipped. Technology is suddenly improving. In just the last couple of weeks, Google suggested Q-day could come as early as ~2029, and new research points to breaking ECC requiring far fewer qubits than previously thought. We still don’t know when quantum will come to reality. But to me, one thing is more clear than ever - when it comes, it will be sudden. For blockchains, dealing with quantum is both a blessing and a curse. Yes many, besides Bitcoin, support “upgrade” mechanisms. But migrating liquidity, wallets, and applications is a nightmare. @arc is built with quantum threat in mind from day one. A practical roadmap allows to both support existing ecosystem of tools and apps built around ECC cryptography, but also have quantum-safe built-in mechanisms (like signatures and checkpoints) to keep assets bullet proof. One of the most unique and interesting aspects of the architecture is that because @arc will leverage confidential compute subspace. Within that subspace, all assets, applications, and transactions will be private and PQ secure by default. So, for instance, you can still generate a traditional ECC key within the subspace, but because of the extra layer of PQ encryption build on top, the keys and interactions fully hidden from adversaries. Stay tuned for more. @jerallaire of @circle explains on @tbpn ⬇️