FAQ

Short answers. The whitepaper and the specification at github.com/zk-coins/zkbtc are the sources.

What is zkBTC?

A one-to-one Bitcoin-backed token on the zkCoins protocol: private transfers, redeemable for on-chain bitcoin. The reserve sits in vaults that spend only along pre-signed BitVM2 fraud-proof paths, not in a custodian.

Can I use it today?

No. This is a design specification and an informative paper. There is no production implementation and no external audit yet. It is not a product you can mint or redeem on mainnet today.

How do I get zkBTC, and how do I get bitcoin back?

Mint: lock bitcoin, wait for deep confirmation of the vault move (on the order of 2016 blocks), then receive the token. Redeem: burn the coin first, then a registered operator fronts bitcoin and reclaims from the vault. There is no un-burn. Set max_fee high enough or the burned coin can sit unserved.

Is there a gatekeeper? Can it freeze my coins?

A gatekeeper is optional per asset and acts only at mint: it can refuse new deposits. It has no key on the vault and cannot freeze transfers or block redemption. After a coin exists, the gatekeeper is out of the path.

Do I have to trust some other operator to exit?

No. Anyone may register as an operator for a deposit epoch, including you. If you register, you can front and reclaim your own exit. A holder who never registers waits for some registered operator. Registration is required beforehand; there is no registration-free self-reclaim on bitcoin as it is today.

Can operators steal the reserve?

Not under the stated assumptions: one honest operator per backing group deletes its setup key, at least one honest live challenger acts in each window, and the circuit and BitVM2 graph are sound. The worst case under those assumptions is freeze, not theft. A critical soundness bug is the theft case, which is why an audit gates any mainnet.

How private is it?

Internal transfers are shielded: amounts, parties, and the graph stay off the public ledger except for a 64-byte nullifier. Peg-in and peg-out are ordinary public bitcoin transactions, so amounts and timing at the boundary are visible.

Why is there no homepage?

On purpose. The official marketing site comes later. The paper lives at /white-paper from day one so that URL stays the one search engines list.