Fee Structure in SupraNova

SupraNova’s fee model is designed to sustain a permissionless, decentralized bridging ecosystem while incentivizing critical actors like relayers and committee updaters.

Fee Overview and Responsibilities

SupraNova applies two levels of fees internally but simplifies the user experience by exposing only the Service Layer Fee during transaction confirmation.

Verification Fee

An internal fee that compensates Committee Updaters for:

• Proof generation
• Signature validation
• Validator public key updates

Paid by: Service Layer (not the user directly)

Service Layer Fee

Visible to users and deducted upon initiating a bridge transaction. It covers:

• Operational costs
• Treasury accumulation
• Relayer and Committee Updater rewards

Then the system separates fees into two distinct layers:

Message Passing Layer Fee

This fee is charged for:

• Verifying Sync Committee proofs
• Verifying ancestry and receipt proofs
• Managing public key updates (Committee Updater work)
• Safe validators committee handovers through public key updates.

Who Charges It?

• The HyperNovaCore verifier contract charges this fee internally. Service-contracts calling the message-passing layer for validation pay this fee as part of the process.

Service Layer Fee (Token Bridge Specific)

This fee is charged by service-specific components like the Token Bridge and includes:

• Operational Service costs.
• Relayer rewards.

Who Sets It?

• The Token Bridge smart contract service owner (typically the protocol team).

How is it Collected?

• A small cut is deducted from the bridged amount (in bridged assets like supETH or supUSDC) at the time of minting.

What Does It Fund?

• Relayer incentives
• Operational treasury buildup

Fee Breakdown Example During a Bridge Transaction

• The net amount minted as supETH will be slightly less than 1 ETH after fees.
• All fees are transparent and visible during the bridge confirmation step.

Incentivizing Liveness

Both relayers and committee updaters are permissionless roles that ensure network liveness and decentralization.

They are incentivized through fee rewards:

Without sufficient rewards:

• Relayers may delay proof submissions
• Committee updates may lapse, compromising security

SupraNova’s modular fee and reward system ensures both roles remain sustainably incentivized.

Fee Model for our Ethereum to Supra Bridge protocol

This protocol involves a Token Bridge Service and a Message Passing Layer. The model details various fees and rewards, including:

• Service Fee (S)
• Relayer Rewards (RR)
• Committee Updater Rewards (CUR)
• Relayer Expense (RG)
• Committee Updater Expense (CUG)
• Verification Fee (V)

Key points of the model:

• Users pay a Service Fee (S) and gas costs when initiating a bridge request.
• Relayers are compensated with Relayer Rewards (RR) that cover their expenses (RG).
• Committee Updaters (CU) are rewarded (CUR) for updating Ethereum sync committee public keys to Supra, covering their expenses (CUG).
• RG and CUG are treated as constants determined by the Admin.

Fee Derivation Formulas

Given traffic estimate X, and gross margins SM, VM, CUM, RM:

• CUR = CUG / (1 - CUM)
• V = (CUR / X) / (1 - VM)
• RR = (V + RG) / (1 - RM)
• S = RR / (1 - SM)

Tiered Service Fee Structure

To accommodate varying bridge volumes, SupraNova introduces a tiered service fee model based on the value bridged in USDT:

SupraNova Address Details

Asset Details

Testnet

Mainnet

Asset Transaction Limit

Mainnet