More Than a Third of All Bitcoin Has Exposed Public Keys, Glassnode Says

About 7.12 million bitcoin, or 35.4% of all supply, are held at addresses whose public key is already visible on the blockchain, according to on-chain analytics firm Glassnode. Those are the coins a future quantum computer could try to steal.

Why it matters

Today these coins are safe. No existing computer can break bitcoin's cryptography. But researchers expect that a large enough quantum computer could one day work out a private key from a public key.

For an ordinary holder, the risk is easy to reduce right now. Glassnode notes that moving coins to a new, never-used address removes the exposure.

Public and private keys, briefly

Every bitcoin address is protected by a pair of keys. The private key is your secret: whoever has it controls the coins. The public key is derived from it and is normally hidden until you spend from an address.

Once you spend from an address, its public key becomes visible on the blockchain forever. If you keep receiving coins at that same address, those coins sit behind a key that anyone can see.

Where the exposed coins are

• 25.8% of supply is exposed because of address reuse, when people receive bitcoin to an address they have already spent from. Of that, 11.6% sits on exchanges.
• The rest is in very old address types, including coins Glassnode attributes to Satoshi Nakamoto, and in newer Taproot addresses. In both, the public key is visible from the start.

What you can do

Use a wallet that gives you a fresh address for every payment. Most modern wallets do this by default. If you hold coins at an old address you have already spent from, sending them to a new address in your own wallet removes the exposure.

Bitcoin developers are also discussing a move to post-quantum cryptography, but no change has been agreed yet.