State Guardian Network Overview
The State Guardian Network (SGN) is a Proof-of-Stake (PoS) blockchain built on Tendermint. The SGN serves as the message router between different blockchains for Celer products in general message passing and cross-chain fund transfers. Celer cBridge and the Inter-chain Messaging Framework (Celer IM) both leverage the SGN in cross-chain transactions for its PoS security, fast finality, and low cost.
PoS and Optimistic-rollup-like Security Models
Inter-chain dApps built on top of Celer can choose from or combine two security models with different trade-offs on delay.
By default, inter-chain dApps rely on the security of the State Guardian Network, which processes messages routed from one chain to another without delay. As a Proof-of-Stake (PoS) blockchain built on Tendermint, the SGN offers security similar to that of Cosmos or Polygon. With CELR as the staking asset, the level of economic security grows with the value of staked CELR. If a guardian acts maliciously, its staked CELR will be slashed entirely by the consensus protocol.
On top of that, an additional layer of optimistic-rollup protection ensures limited risk exposure even under extreme circumstances, e.g. when all the guardians behave maliciously.
In these scenarios, instead of processing a message routed by the SGN instantly every time, an inter-chain dApp can inject a customized delay buffer in high-risk scenarios, and run an independent watchtower service to double-validate the message received. If any inconsistency is detected, it stops the message from being processed before the delay expires.
Celer Inter-chain Messaging Overview
Celer uses MessageBus contracts deployed on chains paired with the State Guardian Network to enable seamless multi-blockchain interoperability. To send a message or invoke a smart contract function across chains, a user or a dApp first send a message with a structured header and arbitrary binary payload to a MessageBus contract on the source chain. Then the validator, the State Guardian Network, will reach a consensus and generate a stake-weighed multi-signature attestation on the existence of such a message. This attestation is then relayed to the destination chain via an Executor subscribing to the message. On the destination chain, the same MessageBus contract checks the validity of the message and triggers the corresponding logic associated with the message either immediately or after a timeout. For a step-by-step example walkthrough, please refer to Celer IM documentation.
CELR Token Utilities and Value Capture
The CELR token is the protocol token for Celer Network. CELR is used as a staking token in the SGN to ensure the economic security of Celer IM. Stake your CELR here.
Similar to using any other PoS blockchain, to use the SGN for message routing, users must pay a fee to SGN validators and their stake delegators to incentivize their work in securing the network.
In addition to these fees, the SGN, as a tendermint blockchain, also issues block rewards for validators that produce a block. CELR tokens have to be staked in the SGN in order to receive these rewards. With staking, validators and stakers actively participate in the operation of the protocol and undertake the risk of slashing: if a validator is malfunctioning or is compromised to act maliciously, part of or all CELR delegated to or staked by this validator will be slashed. Unstaked CELR receive no rewards of any kind.
CELR is also the governance token needed to update and change protocol parameters such as supported chains and tokens, fee configurations for each chain and token, and new modules that will be added. Any upgrade or changes to the SGN as well as these parameters require governance through the SGN with the CELR token.