Architecture

Halo is a privacy-enhanced zkEVM built on Polygon's AggLayer that introduces confidential transactions to the Ethereum ecosystem. By extending the EVM with protocol-level privacy primitives, Halo enables developers to build applications that seamlessly combine public and private state without sacrificing composability, security, or user experience. The architecture leverages Polygon's proven CDK infrastructure and settles to Ethereum L1, ensuring users maintain sovereign control over their assets while accessing meaningful privacy guarantees.

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State

Halo implements a dual-state model that runs two parallel execution contexts within a single unified system. The public state operates as a standard EVM account model with transparent balances, providing full composability with any existing Ethereum application. Traditional DeFi operations, smart contract interactions, and transparent transactions all execute in this context, optimized for operations requiring transparency and interoperability with the broader ecosystem.

The private state introduces encrypted balances stored at the protocol level, enabling confidential transfers that hide amounts and transaction details while maintaining non-custodial ownership through user-controlled private keys. This isn't achieved through separate privacy pools or custodial contracts—instead, privacy is built directly into the account model itself through encrypted balance commitments stored in standard EVM storage.

Users can seamlessly transition between these states based on their operational needs. DeFi operations requiring composability with external protocols naturally use public state, while sensitive transfers leverage private state. This flexibility allows developers to choose transparency or privacy on a per-operation basis without breaking compatibility with existing infrastructure or fragmenting liquidity across isolated systems.

The key innovation here is that privacy is achieved without introducing UTXO state management, separate shielded pools, or custodial intermediaries. The architecture extends the EVM's account model to natively support confidential balances while maintaining full backward compatibility with existing contracts and tooling.