No hype, no price, no panic
Until you spend, the public key is in the box
A hash-based Bitcoin address does not publish its public key. The first spend does. Taproot publishes it on arrival. That is the whole site: a thought experiment that happens to be a checkable fact.
Open the box
Paste an address. The checker looks up whether a spend has already published the key, or whether Taproot opened it on receipt.
Run Schrödinger's Wallet
Closed vs open
The two states that matter. A legend for the checker, not a metaphor stretched past its use.
Read the field guideHow the box is built
The cat is not decoration. Schrödinger's sealed box is how an unspent hash-based address behaves until observation — a spend — publishes the key.
- Why a cat, and why this thought experiment
- The key in the box, and the key that opens it
- How an address labels the box
- Which address types stay closed until a spend
- Address reuse is opening the box twice
- Addresses that were never closed: P2PK and friends
The quantum question, piece by piece
Nothing is broken today. The conversation got louder in 2026 because the estimated runway got shorter. These pages stay on the mechanism.
- Is Bitcoin safe from quantum computers?
- Shor's algorithm, for people who hold keys
- How many bitcoin sit in open boxes
- Taproot opens the box on arrival
- If the coins are on an exchange
- When, if ever, does the runway end
- How to move coins to a still-closed address
- What a later, harder lock might look like
- What BIP-360 actually proposes
- Post-quantum cryptography, simply
- Is Bitcoin more exposed than other coins?
- Satoshi's coins: boxes opened in 2010
Quick answers
- What does CatBitcoin mean by the box?
- Until a hash-based address spends, only a hash of the public key is on-chain. The first spend publishes the key. Taproot publishes it on receipt.
- Are open addresses at risk today?
- No. No existing quantum computer can break secp256k1 in time to steal coins. Open versus closed is a checkable fact, not an emergency.
- Is this investment advice?
- No. There are no prices and no calls to buy, sell, or hold.