For Issuers

ColossusNet gives banks and fintechs a new way to issue payment cards with attractive economics, flexible credit management, and built-in settlement infrastructure.

Revenue

Issuers earn interchange fees of up to 2.50% (250 basis points) on every ColossusNet transaction processed through the issuer-mediated model. The interchange rate is a global network parameter, and the full amount flows to the issuer.

How the collateral model works

Rather than funding transactions through traditional banking rails, ColossusNet uses an on-chain collateral model:

1. Post collateral: Deposit stablecoins into a ColossusNet collateral pool. This pool covers transactions for your cardholders.
2. Fund transactions: When a cardholder taps their card, ColossusNet forwards the card's cryptographic proof to you. You validate the transaction and return a signed funding authorization.
3. Dual-signature settlement: ColossusNet verifies both the card's EMV signature (ECDSA P-256) and your funding signature, then draws from your collateral pool to settle with the merchant instantly.
4. Top up as needed: Periodically replenish your collateral balance. Transactions that would exceed available collateral are declined automatically by on-chain enforcement.

This model gives you full control over your exposure while enabling instant merchant settlement.

Asynchronous cardholder settlement

After the merchant is paid from your collateral pool, you independently retrieve the settlement amount from the cardholder. The cardholder's source chain account has the ColossusNet ERC-7579 modules installed, enabling you to noncustodially retrieve settlement amounts. See Cross-Chain Architecture for the full flow.

Issuer hooks

When cards are registered on ColossusNet, they are bound to your issuer hook, a smart contract you deploy on ColossusNet. The hook executes within the transaction context and validates that txn.origin matches your stored issuer address. This ensures only your authorized systems can draw against your collateral pool.

The hook is registered during the card registration process and is invoked automatically after the card's EMV signature is validated.

Signing API

To participate in transaction authorization, you host a WebSocket signing endpoint:

/api/v1/eth_signRawTransactionSync

The endpoint receives a raw byte stream containing the transaction to be funded. Your system validates the transaction (checking cardholder balance, credit limits, risk parameters, and any other criteria you define) and returns a signed response synchronously.

The WebSocket design is intentional: ColossusNet's measured authorization latency is 172ms, and the synchronous round-trip ensures your authorization decision fits within that window.

Credit limit enforcement

Credit limits and available credit calculations are managed entirely by you through the signing API. When a transaction arrives at your signing endpoint, you evaluate cardholder creditworthiness and balance before returning a signed funding authorization. ColossusNet does not enforce or calculate credit limits; that authority remains with the issuer.

This means you can implement whatever credit policy you choose: traditional credit limits, dynamic risk scoring, real-time fraud checks, or any other logic your business requires.

Card registration flow

Registering a cardholder with an issuer follows a four-step process:

1. Account setup: The cardholder creates an ERC-4337 account with a standard Ethereum key pair (secp256k1 root signer).
2. Card tap: The cardholder taps their ColossusNet card on their phone. The mobile app reads the card via NFC and retrieves the secp256r1 public key and tokenized PAN.
3. On-chain registration: The cardholder submits a transaction registering the PAN, secp256r1 public key, and your issuer hook on ColossusNet. This binds the card to your collateral pool.
4. Source chain module installation: The cardholder installs the EMVValidator and EMVSettlement modules on their source chain ERC-4337 account, enabling you to noncustodially retrieve settlement amounts.

See Card Registration for the full technical flow.

What ColossusNet provides

You focus on credit policy, risk management, and cardholder relationships. ColossusNet handles the rest:

• Settlement infrastructure: Instant stablecoin settlement with merchants from your collateral pool.
• On-chain signature verification: Card EMV signatures validated via the RIP-7212 P-256 precompile.
• Cross-chain bridging: Cardholders and issuers can fund accounts from any EVM chain via LayerZero OFT V2.
• Gas sponsorship: All transaction gas is covered by ColossusNet. Neither you nor your cardholders pay gas fees.
• Immutable audit trail: Every transaction is recorded on-chain for compliance and reconciliation.