RGB Manager

URL: https://rgb-manager.thunderstack.org

The ThunderLink RGB Manager, hosted by ThunderStack, manages RGB state for users. It offers a secure API for tasks such as creating RGB invoices, tracking asset transfers, and building Partially Signed Bitcoin Transactions (PSBTs). This server encapsulates the RGB protocol library, handling both off-chain state and on-chain commitments of RGB.

The overall configuration is customizable to meet the specific operational and security requirements of the customer. It also monitors transfer states and performs background operations such as refreshing in-progress transfers or marking expired ones as failed.

These actions are coordinated by internal watchers that periodically poll the RGB to retrieve the current state and apply necessary updates, such as creating new UTXOs or failing outdated transfers.

Beyond transaction signing, the server is responsible for additional logic around UTXO management: customers can configure the number of UTXOs that should remain available, and the server will ensure this threshold is maintained.

Functional Responsibilities:

API

The service provides a set of HTTP API endpoints (e.g., /invoice, /listassets, /balance) that are protected using Thunderstack JWT access tokens. This ensures that only authorized clients can initiate asset operations or query state.

Additionally, internal communication between the ThunderLink RGB Manager and the ThunderLink RGB Signer occurs over a TLS-secured RabbitMQ connection, ensuring the integrity and confidentiality of all signing requests and responses.

UTXO Management & Monitoring

The server maintains knowledge of owned addresses or UTXOs—either by deriving them from the merchant’s extended public key or retrieving them via ThunderLink RGB manager. This enables it to validate incoming payments, select UTXOs for withdrawals, and manage UTXO fragmentation. Through configurable watchers, the server periodically polls RGB for updated transfer states. It can trigger automated actions such as generating new UTXOs when availability drops below a configurable UTXO limit, or failing expired transfers. These background tasks can be enabled or disabled individually and tuned via environment variables.

Security & Trust

The ThunderLink RGB Manager minimizes risk by never needing users private keys. Users must trust ThunderLink to correctly use the RGB protocol without blocking or misdirecting transactions. Even if ThunderLink is compromised, the attacker can't directly steal assets since merchants have the signing keys. The worst-case scenario is service disruption, like incorrect invoice data or transaction broadcasting failures, which can be mitigated through audit logs and transaction verification by merchants.

Broadcast & Confirmation

After a RGB Signer - signs a PSBT, ThunderLink can send the fully signed transaction to the RGB and monitor confirmations. For incoming payments, it looks for transactions that satisfy invoices, such as detecting UTXO with RGB asset transfers.

PSBT Handling

For outgoing transactions, ThunderLink creates a Partially Signed Bitcoin Transaction (PSBT) with proper inputs, outputs, and RGB commitments. Without private keys, it relies on the RGB Signer for the final signature. PSBT fosters secure collaboration between ThunderLink and Client App by keeping private keys offline. This allows ThunderLink RGB Manager to structure transaction details securely.

State Tracking

The server tracks the merchant's RGB wallet state. It manages necessary data to validate and update asset ownership during transactions. When an invoice is paid, the asset state is updated and documented for the merchant. It also handles synchronization of state updates across transactions.