Glassnode: 6.26 Million BTC Have Exposed Public Keys as Quantum Risks Grow

The findings highlight a growing area of concern for Bitcoin’s long-term security as researchers examine whether future advances in quantum computing could undermine the cryptographic systems used to protect digital assets.

Glassnode’s latest estimate represents an increase of approximately 222,000 BTC, valued at around $18.2 billion at the time of the update, compared with its previous assessment in May. During the same period, Bitcoin’s total issued supply increased by only about 64,000 BTC.

The figures indicate that public-key exposure is expanding considerably faster than new Bitcoin enters circulation. However, the findings do not establish that the affected wallets have been compromised or that their private keys can currently be recovered by attackers.

Bitcoin’s Exposed Supply Has Increased Since May

Glassnode’s May 20 research on Bitcoin’s quantum-exposed supply identified approximately 6.04 million BTC, or 30.2% of issued supply, whose public keys were already visible on-chain.

That proportion has now reached 31.2%, an increase of roughly one percentage point in less than five months. Schultze-Kraft also noted that the share had risen from 24.8% in early 2021, returning to levels last observed around 2016.

Glassnode distinguishes between two main forms of exposure. Structural exposure occurs when a Bitcoin transaction output reveals its public key by design. Operational exposure develops when wallet behavior, particularly address reuse, makes a previously hidden public key visible.

The distinction is important because the two categories require different approaches to reducing exposure. Some balances can be moved to fresh addresses, while others may be associated with inactive wallets, older transaction structures or holders who no longer control their private keys.

Address Reuse Accounts for Most Exposed Bitcoin

According to the October figures, approximately 4.33 million BTC are associated with public-key exposure arising from address reuse, making it the largest contributor to the overall total.

Many Bitcoin address formats initially conceal their underlying public keys behind cryptographic hashes. When coins are spent, the transaction can reveal the corresponding public key. If the address is reused, funds remaining at or subsequently received by that address can become associated with a key already visible on the blockchain.

Another approximately 1.94 million BTC are exposed through transaction-output structures that disclose public keys by design. These include early Pay-to-Public-Key outputs and modern Taproot outputs.

Taproot, introduced in 2021, improves aspects of Bitcoin’s transaction efficiency, privacy and scripting capabilities. Nevertheless, its output structure reveals a public key, meaning Taproot addresses are included in Glassnode’s specific measurement of potential quantum exposure.

These measurements describe cryptographic visibility rather than actual financial losses. The distinction resembles the challenges involved in measuring self-custody losses, where observing blockchain addresses does not automatically establish who controls them or whether a security incident has occurred.

Exchanges Hold 1.79 Million BTC With Visible Public Keys

Centralized cryptocurrency exchanges account for a substantial portion of the exposed supply. Glassnode estimates that approximately 1.79 million BTC associated with exchange-controlled addresses currently have visible public keys.

That represents about 57% of the Bitcoin attributed to exchanges under the firm’s labeling methodology, compared with approximately 55% in May.

Exchange-related exposure increased by roughly 123,000 BTC over the period, accounting for more than half of the overall 222,000 BTC increase.

Exposure varies considerably among platforms. The October figures place Coinbase at approximately 10% of labeled balances with exposed public keys, compared with around 83% for Binance and 100% for Bitfinex.

Glassnode cautions that these percentages should not be interpreted as security rankings or indicators of exchange solvency. They describe the visibility of public keys associated with identified holdings, not whether an exchange’s custody systems are vulnerable to an attack today.

The firm’s analysis also found no exposed public keys among the Bitcoin holdings attributed to the governments of the United States, United Kingdom and El Salvador under its methodology. That finding is limited to the addresses Glassnode identifies as belonging to those governments.

Quantum Computing Threat Remains Theoretical

Public keys are essential to Bitcoin’s transaction-verification system. Their visibility does not ordinarily compromise a wallet because the mathematical problem of deriving a private key from its corresponding public key is considered computationally infeasible using conventional computing methods.

A sufficiently powerful quantum computer running algorithms capable of solving the underlying elliptic-curve problem could theoretically change that assumption.

Research published by Google Quantum AI in March 2026 raised renewed questions about the computing resources that future attacks against cryptocurrency cryptography might require.

However, there has been no confirmed successful AI- or quantum-computing attack capable of recovering Bitcoin or Ethereum private keys from their public keys. Nor does Glassnode’s exposure measurement demonstrate that such an attack is imminent.

The distinction matters because actual wallet-security incidents can arise from software vulnerabilities, malicious authorization requests or operational failures without breaking the underlying cryptography. Recent disclosures involving a bitcoinj wallet vulnerability, for example, concerned payment-processing behavior rather than an attacker deriving private keys from public keys.

Why the Rising Exposure Matters for Bitcoin Investors

The most interesting part of Glassnode’s findings is not necessarily the 31.2% figure itself. It is the direction of the trend.

Bitcoin’s exposed supply has increased substantially faster than its newly issued supply, suggesting that wallet behavior and custody practices are adding to the amount of Bitcoin that could face a particular form of cryptographic risk in the future.

For long-term investors, this creates an uncomfortable distinction between owning Bitcoin today and ensuring that those holdings remain secure over the next decade or longer.

There is no immediate reason to assume that a wallet with an exposed public key is about to be compromised. But preparing for a possible cryptographic transition becomes more complicated as additional coins accumulate in addresses whose keys are already known.

Exchanges are particularly important because they control large identifiable balances and can potentially improve address-management practices across millions of customer accounts. Their custody arrangements are also central to how cryptocurrency exchanges make money, making operational resilience a business concern as well as a technical one.

Even so, reducing public-key exposure should not be confused with eliminating exchange security risks. The recent Bitget backend wallet-system breach demonstrated how transaction-authorization infrastructure can allegedly be compromised even when an exchange says its private keys remained secure.

Bitcoin’s Biggest Challenge May Be Migrating Older Holdings

The harder problem involves Bitcoin that cannot easily move.

A substantial portion of the structurally exposed supply is associated with early Bitcoin addresses, including coins attributed to the network’s earliest participants. Some of these holdings may be permanently inaccessible because their private keys have been lost.

If Bitcoin eventually adopts quantum-resistant signature mechanisms, active holders and exchanges could have opportunities to migrate their assets. Lost or inaccessible coins would present a much more difficult question.

Any attempt to address those holdings through protocol changes could raise disagreements about property rights, Bitcoin’s monetary rules and whether coins that cannot move should receive special treatment.

There is also an important technical limitation to consider: transferring Bitcoin to a fresh address that conceals its public key can reduce the exposure measured by Glassnode, but it does not make Bitcoin’s existing signatures quantum-resistant. Public keys may still become visible when transactions are spent.

That means a durable solution would likely require more than encouraging investors to stop reusing addresses. Wallet compatibility, new signature standards, transaction costs and broad network agreement would all become part of the discussion.

For now, the most useful indicators are whether exposed balances continue growing, whether major custodians change their address-management practices and whether Bitcoin developers make measurable progress toward quantum-resistant transaction mechanisms.

Glassnode’s figures do not signal an immediate Bitcoin security crisis. They do, however, show that the amount of Bitcoin requiring attention in a future cryptographic transition is already substantial. The longer preparation is delayed, the more complicated that transition could become.