# Architecture

General system design of Bool Network.

### Underlying Technologies Bool Network is the first permissionless cross-chain protocol based on Multi-Party Computation (MPC), Trusted Execution Environment (TEE), and Zero Knowledge Proof (ZKP) to facilitate omnichain interoperability across heterogeneous ecosystems. We furthermore proposed [Ring VRF](https://docs.bool.network/dynamic-hidden-committee-dhc/lifecycle#ring-vrf-protocol), a ZKP-based protocol to guarantee the underlying security of the system. Technical details about Ring VRF can be found in this [paper](https://ieeexplore.ieee.org/document/9903072). ### Key Components In general, the kernel of Bool Network consists of three main modules: Dynamic Hidden Committees, BoolChain and an External Relayers System. Each of these is described below, along with their functionality in Bool Network. #### [Dynamic Hidden Committees (DHC)](#dynamic-hidden-committees-dhc) * Security guards in Bool Network to ensure the safety of cross-chain messages from the application layer. * Each committee manages a unique private key which has been distributed to a specific group of MPC nodes. * Each collection of private key fragments is separately stored in the TEE hardware of a committee's members, i.e. MPC nodes. * Ring Verifiable Random Function (Ring VRF) protocol is the underlying algorithm to protect and prove the committee's membership of an MPC node. #### Bool Chain * A public chain which performs as an ordinarily distributed ledger. * At the early stage, the chain is specialized to support and record the lifecycles and actions of [Dynamic Hidden Committees](https://docs.bool.network/interoperability-protocol/dynamic-hidden-committee-dhc) in the network. * It is an EVM-compatible blockchain where applications can be built on top of the Bool Chain in the future. #### External Relayers * Refer to participants who are responsible for submitting destination transactions in Bool Network. * Designed as a competitive, efficient, and highly accessible system which is open to the market. * Participants can profit from each transaction that they submitted to the destination chain. * Do not guarantee the security of cross-chain messages. ### Infrastructure Layer We deployed several primary contracts on each blockchain to help developers build their omnichain applications on Bool Network: * `AnchorFactory`: deploy `Anchor` contracts which serve as application-specific endpoints to connect users' contracts with the core module of Bool. * `Messenger`: an official cross-chain message delivery port which connects to all the anchor contracts on the same chain. It has two main functionalities: transmit source chain messages to Bool Network and forward messages to registered anchor contracts on the destination chain. {% hint style="info" %} The above description of the infrastructure layer only fits ecosystems that have smart contracts or similar structures. The alternative design for exotic networks will be published in the future. {% endhint %} ### Application Layer This layer contains all the ecosystems/protocols/applications built on top of BOOLNetwork, including but not limited to tokens, NFTs, DeFis, cross-chain protocols, Oracles and public chains.