Coinbase Wrapped BTC

cbBTC is available on three major blockchain networks:

• Ethereum: cbBTC can be used on Ethereum’s extensive DeFi ecosystem.
• Base: Coinbase’s layer-2 network, Base, offers a secure and scalable environment for cbBTC transactions.
• Solana: As an SPL token on Solana, cbBTC allows users to engage with Solana’s high-speed, low-cost applications.

These networks provide different options for users to access cbBTC within various blockchain ecosystems, enabling interaction with decentralised applications specific to each network.

The cbBTC minting and burning process ensures that each cbBTC token is fully backed by an equivalent amount of BTC held in Coinbase reserves. The minting and burning process operates as follows:

• Minting: When a user initiates a withdrawal of BTC from their Coinbase account to one of the supported networks (Ethereum, Base, or Solana), an equivalent amount of cbBTC is minted and transferred to the user’s wallet address.
• Burning: When cbBTC is deposited to a Coinbase-specific address, the cbBTC is burned, and the corresponding amount of BTC is released from Coinbase's custody and credited to the user’s BTC account.

This process is facilitated by smart contracts on each network, designed for transparency and security. These contracts are part of the Coinbase wrapped token framework, also used in cbETH, and are accessible as open-source resources on GitHub. The current total supply of cbBTC on each network can be verified through blockchain explorers like Etherscan, BaseScan, and Solana Explorer.

The BTC backing cbBTC is held by Coinbase in a combination of hot and cold wallets, managed securely within the United States and Europe. Private keys are encrypted and require multiple human operators for decryption, ensuring no single individual controls Coinbase’s private keys. Coinbase performs regular audits and reconciliations with blockchain data to confirm that cbBTC issuance aligns with BTC reserves.

Control over the cbBTC smart contract is managed by a role-based key system, including roles for:

• Admin: Can upgrade the wrapped token implementation.
• Owner: Can assign roles except the Admin.
• Blacklister: Can restrict addresses from transferring, minting, or burning.
• MasterMinter: Can assign minters and set minting limits.
• Minter: Can mint and burn tokens.
• Pauser: Can suspend contract activities like transfers, mints, and burns.

On Solana, cbBTC operates as an SPL token, with equivalent controls in place for minting and freezing under Coinbase’s key management system.