More than 6 million bitcoin sit behind exposed public keys, Glassnode data shows, as "bunker mode" warnings spread

More than 6 million bitcoin — 31.2% of circulating supply — now sit behind public keys that are already visible on-chain, according to Glassnode figures reported by CoinDesk on October 8. That is roughly 5 to 6 percentage points above the low reached in 2023.

A visible public key is not, by itself, a breach. The number measures address usage, not an active threat. No practical attack on bitcoin or ether wallet keys has been demonstrated. The concern is theoretical: a public key becomes exposed through address reuse, or appears directly in certain output types — early pay-to-public-key outputs and Taproot — and a sufficiently capable quantum computer or an undiscovered mathematical shortcut could, in principle, derive the private key from it.

Glassnode co-founder Rafael Schultze-Kraft said exposed supply has risen by 222,000 BTC (about $18.2 billion at the prices cited) since the firm's May report, while total supply grew by just 64,000 BTC. Exchanges account for 123,000 BTC of that increase and now hold 1.79 million BTC behind visible keys. Exposure varies sharply by custodian: Coinbase sits at 10%, Binance at 83%, Fidelity at roughly 2% of about 375,000 BTC, Grayscale at 49%, and Revolut and Robinhood at 99% and 100% respectively. U.S., U.K. and El Salvador government holdings show no exposure under this methodology.

The update lands alongside a warning from Ethereum researcher Justin Drake, who urged the industry into "bunker mode," arguing that in a worst case AI could find a shortcut to breaking wallet cryptography "in months, not years," ahead of quantum machines. That is Drake's scenario, not a consensus view — and, per CoinDesk, it has divided crypto.

Key facts

• 6 million+ BTC (31.2% of supply) behind visible public keys; ~5–6 points above the 2023 low — Glassnode, via CoinDesk.
• Exposed supply up 222,000 BTC (~$18.2B) since May; total supply up 64,000 BTC — Schultze-Kraft.
• Exchanges hold 1.79M BTC exposed; +123,000 BTC since May — Glassnode.
• Custodian exposure: Coinbase 10%, Binance 83%, Fidelity ~2%, Grayscale 49%, Revolut 99%, Robinhood 100% — Glassnode.
• No practical key-cracking attack has been demonstrated — CoinDesk.

The real-world read

The headline number is big, but the framing is doing work. "Exposed" here means a public key is visible, not that any coin is at risk today — the data tracks address behavior, and CoinDesk is explicit that no working attack exists. Drake's "months, not years" line is a worst-case hypothetical from one researcher, offered without a demonstrated mechanism; treat it as a prompt to prepare, not a forecast. Worth noting the single available account is secondary: CoinDesk relaying Glassnode's own data and Schultze-Kraft's framing. The percentages invite custodian-shaming, but a high exposed share says nothing about any platform's actual security absent an attack that can use it.

Opinion, and whose

Justin Drake (Ethereum researcher): the industry should enter "bunker mode" and prepare now, because AI could plausibly break wallet cryptography before quantum computers arrive. This is his view, contested within the field.

Sources

• CoinDesk (Tier 2, secondary), Oct 8, 2026 — reported Glassnode's figures and custodian breakdown, Schultze-Kraft's comments, and Drake's "bunker mode" remarks; itself citing Glassnode data as the primary source. No marketing or sponsored material used from the article.

Not financial advice.