Why privacy is the missing piece for Bitcoin in DeFi

Bitcoin was meant to carry privacy. Even if that wasn’t the headline of the project, it was woven into how the system was supposed to work.

The cypherpunk vision was money that didn’t ask permission and didn’t announce itself. The whitepaper spelled out one piece of that: use a fresh address every time so your transfers can’t be linked together. Privacy was a property the system was supposed to carry by default.

Address reuse, KYC exchanges, and a chain analysis industry that grew up alongside the asset quietly turned Bitcoin’s pseudonymity into a public spreadsheet. By the early 2020s, most active wallets were identifiable to the major firms. The infrastructure for tracing flows, attaching identity, and selling that picture became a mature industry.

What being public actually costs

Public chains have real upside, and none of that is in dispute.

What gets glossed over is what being public costs the people on the other side of the lens. The visibility isn’t selective. The same data that helps regulators and auditors also helps MEV searchers, competitors, analytics firms, and anyone curious about your money. All of them get it at once, forever, with no way for the owner to take any of it back.

For Bitcoin specifically, that cost lands harder than for most other assets. BTC was issued by no one, distributed to nobody in particular, and the original promise was that nobody had to know who held it. Bitcoin did not make money public so every holder could be watched. It made money verifiable so no holder had to be trusted.

The most measurable cost is extraction

A BTC swap on a public AMM tells every sandwich bot in the mempool exactly what you’re about to do, and they make you pay for the privilege. A treasury rebalance from a known wallet moves the price against itself the second it lands.

The metadata is worse than the trades. If your wallet is public, so are your counterparties, where your assets came in from, who custodies your cold storage, which OTC desk handled the last big fill, and the protocols you actually use. All of it composes into a complete picture of how you operate, sitting in front of competitors and analytics firms forever.

DeFi makes this sharper. Wrapping BTC and putting it on smart contract rails takes the most surveilled asset in crypto and surveys it harder. Every swap, every deposit, every move becomes a permanent public entry attached to an address that has almost certainly already been labelled. Once labelled, it sticks.

Bitcoin in DeFi has been pitched for years. The infrastructure has been ready. The adoption hasn’t followed. Nobody seriously wants to move size onto a system where every move is broadcast to everyone, forever. For individuals, that picture isn’t abstract. Once your wallet is doxxed and the size is visible, you become an addressable target. For institutions, it’s a deal-breaker.

Without privacy, BTC in DeFi doesn’t matter.

A regulator can audit your account. Your neighbour can’t

The fix is the right kind of transparency, flowing to the right people.

Helen Nissenbaum calls it contextual integrity: information should flow according to the norms of the context it belongs to. A bank knows what you bought. A neighbour doesn’t. A regulator with legal authority can compel disclosure. A stranger can’t. That’s the norm that public chains broke in 2009. But math can fix it.

In 2013, at one of the earliest Bitcoin conferences hosted in San Jose, Eli Ben-Sasson gave a talk about proving something is true without revealing the thing itself. That work became the foundation of zero-knowledge proofs in this industry. It became Zcash. It became StarkWare. It became Starknet.

Now it’s coming back to Bitcoin.

Enter: strkBTC

strkBTC is Starknet’s privacy layer for Bitcoin. Not a dApp, not a feature bolted onto something else. Part of the infrastructure. A user bridges native BTC from Bitcoin to Starknet and receives strkBTC, a Bitcoin backed asset that can be used across the Starknet ecosystem.

Once strkBTC has been received, users can access optional privacy features, such as shielding balances and private transactions. Selected activity can be kept confidential from public observers, while the protocol still verifies that transactions are valid. The privacy is cryptographic. It is enforced by math, not promised by an intermediary. In the event of legitimate legal requirements, an authorised audit trail can be reconstructed for a specific user through controlled disclosure, without compromising the privacy of the broader network. Privacy strengthens with adoption: the wider the anonymity set, the harder it becomes to isolate any one user’s activity. Bitcoin does not need secrecy, it needs privacy with the right boundaries.

In 2010, someone asked Satoshi what he thought about zero-knowledge proofs. He replied: “This is a very interesting topic. If a solution was found, a much better, easier, more convenient implementation of Bitcoin would be possible.”