Glassnode: Address reuse puts 30% of Bitcoin supply at quantum risk

Glassnode says that about 30% of the Bitcoin supply is at quantum risk

Glassnode said that about 30% of the Bitcoin supply is exposed to quantum risk because the public key behind this part of Bitcoin already appears on the chain. Most of these risks stem from address reuse, part of the cost, and hosting behavior, rather than the overall structure of the network.

In a new report, Glassnode used quantum exposure analysis to find that 6.04 million bitcoins (30.2% of the circulating supply) were already located in public addresses where public keys were already available. This figure forms the basis for the core conclusion of approximately 30%.

Quantum exposed Bitcoin supply: 6.04 million BTC (30.2%)

Glassnode attributed this to the public key already visible on the chain. Under the same framework, the remaining 13.99 million BTC (accounting for 69.8% of the supply) did not show public key exposure in a static state. The public key for this part of Bitcoin remains hidden until it is next spent.

Glassnode's assessment quantifies Bitcoin's quantum risk into specific numbers

The importance of this assessment is that it translates long-standing theoretical concerns into specific supply data. In theory, quantum computers capable of cracking elliptic curve cryptography can derive private keys from public public keys, and Glassnode's work quantifies the proportion of supply currently in this state.

The key is that this figure of about 30% is not caused by address reuse alone. Glassnode divides the exposed supply into two categories: structural exposure was 1.92 million BTC (9.6% of supply), resulting from script design, such as the oldest "pay-to-public key" format; and the larger portion was operational exposure, at 4.12 million BTC (20.6% of supply), related to address reuse, partial spending, and hosting behavior rather than scripting design. This part is directly related to the way the holder actually uses the wallet.

Operative quantum exposure: 4.12 million BTC (20.6%)

This is part of what Glassnode attributes to address reuse, partial spending, and hosting behavior rather than structural script design.

Here, the title statement may be misleading. If reports blame all 30.2% of address reuse, they exaggerate the mechanism: only 20.6% of the operational part falls into this category, while 9.6% of the structural part depends on the address type itself.

Why address reuse is critical to Bitcoin quantum risk discussions

Address reuse simply means receiving new funds again at the same address that was already used to send Bitcoin. Since one spend exposes the address's public key, any balance sent back to the address later remains exposed in a static state.

An academic paper on quantum exposure supports the same logic. The paper points out that the quantum exposure status of a Bitcoin depends exactly on whether its public key is visible on the blockchain, and emphasizes that address reuse exposes remaining or future balances after first spending.

Because of this, wallet behavior (not just the underlying scripts) determines the level of risk. Holders who never reuse addresses will hide the public key until spent, while repeated reuse will keep the public key open for anyone to analyze, including future quantum computers.

What this finding means for Bitcoin holders and the market narrative

For holders, the practical implications lie in wallet hygiene: use a new address every time it is received and avoid reuse, thereby limiting the balance exposed in a static state. Custody providers also face this large-scale problem because exchange summary balances are also operational exposure.

This framework also sparked ongoing security discussions rather than price events. Developers are evaluating migration paths, such as the BIP-360 proposal for quantum-resistant outputs, a response that goes in parallel with technology evaluations rather than immediate regulatory triggers.

Market conditions remained sluggish during this discussion. Bitcoin is trading at close to $64,615, and the Fear and Greed Index reads 26 (Fear). Discussions of quantum risk have not yet translated into significant price volatility, similar to Bitcoin's recent trend of testing resistance as ETF flows cooled.

The discussion comes at a time when market caution is spreading. As the outflows of Bitcoin ETF funds accelerate with widespread sell-off of risky assets, and as holders endure billions of dollars in realized losses amid volatility, market attention remains focused on the flow of funds. In this context, Glassnode's numbers are more like a long-term resilience indicator than a warning of an imminent attack.