Glassnode Warns About the Quantum Vulnerability of Six Million Bitcoins

The threat of quantum computing on Bitcoin network security has just taken a concrete and quantified turn. A shocking report published by the analysis firm Glassnode throws a stone in the pond: 6.04 million bitcoins are today vulnerable to decryption by a quantum computer. This represents 30.2% of the total circulating supply.

6.04 million BTC in the crosshairs

According to Glassnode, 6.04 million BTC are in addresses where the public key is already visible on the Bitcoin blockchain. The remaining 13.99 million BTC do not have this exposure. That amounts to 69.8%.

Why is this critical? A sufficiently powerful quantum computer (notably a CRQC) could reconstruct a private key from the known public key alone using Shor’s algorithm. The attacker would then not need to wait for the owner to move their funds. The bitcoins would be accessible directly, in dormant state.

Satoshi era bitcoins constitute the most persistent form of exposure. If they are lost or abandoned, they will never be able to migrate to more secure address structures. They would therefore remain exposed indefinitely.

Glassnode specifies that this analysis does not predict the date or even the certainty of a quantum attack against Bitcoin. It is a mapping of existing vulnerabilities.

Two distinct types of exposure for the Bitcoin network

The first is structural. Some types of addresses reveal the public key by design, regardless of the behavior of their owner. This is the case for old P2PK outputs, notably used by Satoshi Nakamoto, as well as modern Taproot addresses. This category represents 1.92 million BTC, or 9.6% of the total supply.

Operational exposure is the core of the current problem. It totals 4.12 million BTC, or 20.6% of the supply. It arises from poor practices:

• address reuse;
• partial spending;
• insufficient custody management.

The study points out a major culprit in this operational exposure: centralized bitcoin trading platforms. By themselves, cryptocurrency exchanges hold 1.66 million bitcoins at risk due to simplified internal management mechanisms that recycle deposit addresses for their clients. This massive concentration of unprotected liquidity against the quantum risk indirectly weakens the Bitcoin ecosystem.

In any case, the debate around quantum risk could now accelerate the technical evolution of bitcoin. Future network updates will probably aim to protect funds before the actual arrival of quantum computers.