Starknet Launches strkBTC: A New Privacy-Focused Bitcoin Token with Shielded Balances

Starknet Introduces strkBTC: A Privacy-Enhanced Bitcoin Token

On May 12, Starknet launched strkBTC, a new ERC-20 token backed by Bitcoin locked on the Bitcoin base layer. This innovation brings shielded balances into a smart contract environment at scale, offering users enhanced privacy options.

Public and Shielded Modes for Enhanced Privacy

The token operates in two modes:

• Public mode: Functions like other wrapped Bitcoin assets, with all balances and transactions visible on-chain.
• Shielded mode: Allows users to hide selected balances and transfers from external observers, providing greater privacy for sensitive financial activities.

Selective Disclosure and Regulatory Compliance

Starknet routes viewing keys to an independent third-party auditor, enabling selective disclosure when required by regulators or counterparties. This ensures compliance while maintaining user privacy.

Federation Manages Bitcoin Movement

A five-member federation oversees the movement of Bitcoin between the Bitcoin network and Starknet. The federation’s roadmap includes reducing trust assumptions over time, moving toward a more decentralized and secure model.

Bridge Providers Enable Liquidity

Atomiq and Garden provide bridge routes from Bitcoin (BTC) and Wrapped Bitcoin (WBTC) into the new strkBTC token, facilitating liquidity and adoption.

Development Timeline: From Concept to Launch

The rapid development of strkBTC reflects the growing demand for Bitcoin privacy solutions outside the Bitcoin protocol itself. Key milestones include:

• April 10: Starknet published its privacy argument, framing on-chain visibility as incompatible with real-world financial use.
• April 20: Version v0.14.2 went live, introducing native in-protocol proof verification and the infrastructure layer for encrypted balances.
• April 28: Starknet confirmed that Atomiq and Garden would wire BTC and WBTC liquidity directly into strkBTC.
• May 7: Starknet disclosed the five-member federation responsible for managing Bitcoin movement.
• May 12: The product officially launched, completing the 32-day journey from privacy thesis to live product.

The Bitcoin Privacy Challenge

Bitcoin’s transparent ledger design ensures every transaction is verifiable, and every address is traceable. While this transparency is a core feature, it poses operational challenges for entities such as:

• Corporate treasury managers
• Large-value OTC desks
• Any entity preferring not to disclose full wallet balances publicly

The market has responded by building privacy solutions in adjacent systems that can iterate faster than Bitcoin’s base layer.

Existing Privacy Solutions in Bitcoin Adjacent Systems

Liquid Network: Confidential Transactions

Liquid, developed by Blockstream, has operated on this principle for years. Users lock BTC into the peg and receive L-BTC on a sidechain where Confidential Transactions hide both the asset type and amount from outside observers. This makes third-party inspection of amounts impossible.

Key features of Liquid include:

• Federation-based block signing
• Federation infrastructure handling peg-outs
• Users trade Bitcoin’s security model for Liquid’s in the process

WBTC Paired with RAILGUN: Privacy in EVM Territory

WBTC brings Bitcoin exposure to Ethereum, while RAILGUN shields ERC-20 assets in private zk-balances. Users can send, swap, and interact with DeFi without these actions appearing on a public ledger.

Key considerations:

• RAILGUN requires assets to be in ERC-20 form before shielding.
• The privacy layer covers Bitcoin-derived instruments that have already crossed into Ethereum.
• WBTC’s issuer and bridge touch Bitcoin before RAILGUN can apply its privacy features.

Fedimint and Cashu: Privacy Through Custody

Fedimint and Cashu build privacy through custody models. Users deposit Bitcoin into a federated system and receive private payment claims in return. In Fedimint’s case, federation guardians cannot trace individual members’ balances or transactions, enhancing privacy.