Bitcoin Public-Key Exposure Reaches 6.26 Million BTC
An estimated 6.26 million BTC, equivalent to 31.2% of Bitcoin’s total supply, is held in addresses where public keys are already visible on the blockchain. The figure, highlighted by Glassnode co-founder Rafael Schultze-Kraft in a post on X, has renewed discussion about Bitcoin’s long-term cryptographic security.
The estimate marks an increase from 24.8% of Bitcoin’s supply in early 2021, bringing the proportion back to levels last seen around 2016. Glassnode’s May 2026 analysis of Bitcoin’s quantum-exposed supply counted approximately 6.04 million BTC, or 30.2% of supply. The newer estimate therefore represents an increase of roughly 220,000 BTC in less than five months.
Public-key exposure does not mean these coins have been compromised or can be stolen using conventional computing technology. The concern is that sufficiently powerful future technology could potentially use a visible public key to derive its corresponding private key, which controls the funds. The risk depends on advances in cryptography-breaking capabilities, including potential breakthroughs in quantum computing.
Why Some Bitcoin Addresses Reveal Their Public Keys
Bitcoin uses public-key cryptography to authorize transactions. In many address types, a cryptographic hash of the public key is used instead of displaying the full key in the receiving address. When a user spends funds, the transaction generally reveals the public key needed to verify the signature.
One significant source of exposure is address reuse. When someone spends from an address and continues receiving Bitcoin at that same address, the public key may remain visible onchain. Glassnode’s figures put approximately 4.33 million BTC in this category, up from 3.79 million BTC over the preceding year. That represents about 21.5% of circulating Bitcoin supply, based on the cited estimates.
The remaining 1.94 million BTC is associated with script types that expose public keys through their spending structure. This includes approximately 1.71 million BTC in pay-to-public-key (P2PK) outputs, an early Bitcoin transaction format that directly embeds the public key. Around 1.10 million BTC in this category is attributed to Satoshi Nakamoto. Another 222,000 BTC is held in Taproot outputs, which use public keys in their output structure.
These categories illustrate why the exposure estimate is not limited to people reusing addresses. Some Bitcoin outputs were created using formats that reveal public-key information by design.
Exchanges Account for a Significant Share of Exposed Bitcoin
Cryptocurrency exchanges also hold substantial amounts of Bitcoin in addresses with visible public keys. Approximately 1.79 million BTC held by exchanges falls into the exposed category, representing around 57% of identified exchange holdings, based on figures shared by Wu Blockchain.
The distribution differs considerably among platforms. Glassnode’s May report estimated that around 5% of Coinbase’s Bitcoin balances were exposed, compared with approximately 85% for Binance and 100% for Bitfinex under its methodology. These percentages describe the reported exposure of identified holdings, not whether an exchange has suffered a breach or whether its customers’ funds are currently vulnerable to theft.
The differences reflect the way platforms manage Bitcoin deposits, withdrawals and wallet structures. Address formats and reuse practices can affect whether public keys are visible, meaning the same exposure rate should not automatically be assumed across all custodians.
For the broader Bitcoin ecosystem, the figures highlight the importance of understanding how funds are stored and how different transaction formats reveal cryptographic information. However, the amount of exposed supply alone does not establish that an attacker has the ability to derive private keys.
AI Raises New Questions About Bitcoin’s Cryptographic Security
The figures have attracted additional attention amid a debate over whether artificial intelligence could accelerate advances in mathematics and cryptanalysis. Ethereum Foundation researcher Justin Drake recently raised concerns about the potential speed of progress, warning in a worst-case scenario that AI-accelerated mathematical breakthroughs could threaten the Elliptic Curve Digital Signature Algorithm (ECDSA) within “months rather than years.”
ECDSA is a digital signature scheme used by Bitcoin to authorize transactions. If an attacker could derive a private key from a corresponding exposed public key, the attacker could potentially create valid signatures and attempt to spend the associated funds.
The warning does not mean such a capability has been demonstrated. It describes a potential threat scenario, and the timeline remains uncertain. AI-driven advances and quantum computing are also distinct issues: improvements in AI-assisted research would not, by themselves, establish that a practical quantum computer or a working method for breaking Bitcoin’s cryptography exists.
The debate has nevertheless prompted developers and researchers to examine long-term security assumptions more closely. Discussions across the crypto industry have included both the potential severity of future cryptographic threats and the risks of responding too quickly without a well-tested migration process.
Vitalik Buterin Warns Against Rushed Wallet Migrations
Ethereum co-founder Vitalik Buterin has argued that users should take cryptographic risks seriously without rushing to move their assets immediately. In a post on X, he said he did not recommend that people scramble to move their funds to new wallets that day.
Buterin also warned about the dangers of hurried technical changes, stating: “It is very easy to lose funds from a misconfigured rushed upgrade. I personally have lost more money in botched migrations than I have lost in all hacks.”
His position highlights a practical trade-off: leaving a wallet unchanged may carry long-term risks if the underlying cryptography becomes vulnerable, but moving assets without understanding the process can introduce immediate operational risks. Mistakes involving wallet setup, private keys, transaction details or recovery procedures can lead to permanent losses.
For Bitcoin holders, the discussion does not establish a universal need to transfer funds immediately. Any future migration strategy would need to account for wallet compatibility, security practices and the technical details of any proposed cryptographic upgrade.
Arthur Hayes Sees Fear as Another Market Narrative
BitMEX co-founder Arthur Hayes has taken a more market-focused view of the growing concern. In a post on X, Hayes grouped what he called “AI encryption FUD” with earlier periods of market anxiety, including the 2017 block-size wars, the COVID-19 shock in 2020 and the 2023 FTX collapse.
His comparison reflects the view that major fear-driven narratives can influence crypto market sentiment, even when their long-term consequences remain uncertain. It does not, however, resolve the underlying technical question of whether AI could materially accelerate attacks against existing cryptographic systems.
The central issue remains the difference between a theoretical vulnerability and a practical attack. Glassnode’s estimates identify Bitcoin held in outputs with visible public keys, while the AI debate concerns how quickly cryptographic assumptions might be challenged in the future.
For now, the reported 6.26 million BTC figure provides a measure of potential exposure rather than evidence of an ongoing compromise. The next steps depend on continued cryptographic research, careful assessment of emerging capabilities and secure migration plans if meaningful vulnerabilities are established.
