Question 1

What is Coinbase Wrapped BTC (cbBTC)?

Accepted Answer

Coinbase Wrapped BTC (cbBTC) is a wrapped token backed 1:1 by Bitcoin (BTC) held securely by Coinbase. For each cbBTC in circulation, an equivalent amount of BTC is stored by Coinbase in custodial solutions, including cold storage. As a wrapped asset, cbBTC represents BTC on-chain, enabling it to be used in decentralised applications (DeFi) across multiple blockchain networks. Users can unwrap cbBTC and redeem the corresponding BTC by depositing cbBTC back into their Coinbase accounts. cbBTC is designed to work seamlessly with DeFi applications on compatible networks, expanding BTC’s use cases and financial utility.

Question 2

What is Coinbase Wrapped BTC (cbBTC) used for?

Accepted Answer

cbBTC allows users to engage with a variety of on-chain financial applications. With cbBTC, users can utilise BTC in DeFi ecosystems for purposes such as providing liquidity in DeFi protocols, using cbBTC as collateral to borrow other crypto assets, or making payments on supported platforms. This token allows BTC to be used in new ways without requiring users to transfer their original Bitcoin from Coinbase’s custody. By representing BTC on-chain, cbBTC contributes to a more liquid and accessible digital financial ecosystem.

Question 3

Supported Networks

Accepted Answer

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.

Question 4

Minting and Burning Process

Accepted Answer

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.

Question 5

Custodianship and Governance

Accepted Answer

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.

Question 6

Security Measures & Compliance

Accepted Answer

Coinbase employs advanced wallet infrastructure, regular audits, and real-time monitoring to secure the BTC held as cbBTC backing. The smart contracts for cbBTC undergo thorough testing by third-party security auditors, including OpenZeppelin, which has also audited cbETH, the base for cbBTC’s contract. Coinbase complies with regulatory requirements, including Anti-Money Laundering (AML) and Know Your Customer (KYC) obligations, and holds relevant crypto asset licences in various jurisdictions, such as the United States, Germany, Singapore, and Bermuda.


cbBTC	ERC20	BASE	0xcbB7C0000aB88B473b1f5aFd9ef808440eed33Bf	2024-08-20
cbBTC	ERC20	ETH	0xcbb7c0000ab88b473b1f5afd9ef808440eed33bf	2024-08-20
cbBTC	SPL	SOL	cbbtcf3aa214zXHbiAZQwf4122FBYbraNdFqgw4iMij	2024-10-23
cbBTC	ERC20	ARB	0xcbb7c0000ab88b473b1f5afd9ef808440eed33bf	2024-11-08