Design Choices

Privacy-Enhanced EVM Architecture

Halo extends Ethereum's execution environment with native privacy capabilities while maintaining full EVM compatibility.

Most privacy solutions force developers to choose between privacy and usability — requiring custom virtual machines, specialized wallets, or sacrificing security guarantees. Halo rejects these trade-offs by working backwards from three fundamental design principles:

Security: Can't Be Evil > Don't Be Evil

Halo inherits Ethereum's security model through Polygon's AggLayer, which settles all state transitions to Ethereum L1. Even if Halo's sequencer goes rogue or the network experiences downtime, users maintain sovereign control over their assets through Ethereum-native exit hatches. This would be impossible on new L1 blockchains or sovereign rollups, where canonical state is defined by their own validator sets rather than Ethereum's consensus.

By building as a zkEVM rollup rather than a standalone chain, Halo ensures that privacy doesn't come at the cost of security. Users can always prove and withdraw their balances directly on Ethereum L1, making censorship or fund seizure cryptographically impossible without compromising Ethereum itself.

Composability: Privacy Without Isolation

Composability is the defining feature of the Ethereum ecosystem — the ability for applications to interoperate trustlessly, share liquidity, and build upon one another like money legos. Most existing privacy solutions sacrifice this by introducing custom virtual machines, new smart contract languages, or isolated execution environments that make it impossible to leverage existing EVM codebases or DeFi primitives.

Halo preserves full EVM composability. Any existing Ethereum-compatible contract, stablecoin, or application can be deployed without modification. Developers can integrate privacy into existing protocols with minimal changes rather than rewriting them for a new stack. This means Halo applications can interact with the broader Polygon ecosystem — accessing liquidity from POL, zkEVM, and other AggLayer chains while maintaining privacy guarantees when needed.

The architecture introduces protocol-level privacy primitives that work alongside standard EVM operations, allowing developers to choose transparency for DeFi composability or privacy for sensitive operations on a per-transaction basis.

Wallets: Zero Friction for Users

The first point of interaction with any blockchain is a wallet. Most privacy systems require specialized wallets, custom transaction formats, or new signing standards that alienate users and slow adoption. This creates a critical barrier to entry — if users must download new software, manage new keys, or learn unfamiliar interfaces, privacy becomes a feature only accessible to the technically sophisticated.

Halo eliminates this friction completely. Users interact with Halo through the same interfaces they already trust — MetaMask, Rabby, Frame, or any standard Ethereum wallet — using familiar transaction flows and signing standards. There are no browser extensions to install, no new seed phrases to manage, and no custom UX to learn.

This allows any user familiar with Ethereum to access private functionality on Halo instantly, without switching networks, bridging assets to unfamiliar chains, or learning new tools. Privacy becomes as accessible as any other DeFi application, rather than a specialized feature requiring technical expertise.

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