Bitcoin's long-term security is facing renewed scrutiny after Glassnode co-founder Rafael Schultze-Kraft estimated that 6.26 million BTC, representing 31.2% of the cryptocurrency's supply, sits in addresses with exposed public keys.Â
The findings follow an urgent warning from Ethereum Foundation researcher Justin Drake, who urged the blockchain industry to prepare for a potential cryptographic breakthrough that could put existing wallets at risk.
“Today I call upon the blockchain industry to calmly begin planning for ‘bunker mode,†Drake wrote in a post on X Wednesday, recommending a controlled migration of assets to fresh addresses whose public keys remain hidden behind a hash.
Drake warned that the threat might emerge sooner than anticipated, arguing that “it is now reasonable to brace for the possibility that ECDSA breaks before qday, in the worst case in months, not years.â€
For context, ECDSA is the digital signature scheme Bitcoin uses. A sufficiently powerful quantum computer could theoretically exploit its mathematical structure to recover private keys from exposed public keys. Drake also raised the possibility that advances in artificial intelligence could accelerate mathematical breakthroughs that weaken existing cryptography.



 
According to Rafael's analysis, 4.33 million BTC have exposed public keys because of address reuse. Another 1.94 million BTC are exposed through their transaction or script types, including approximately 1.71 million BTC held in legacy Pay-to-Public-Key (P2PK) outputs. This category includes around 1.1 million BTC attributed to Bitcoin creator Satoshi Nakamoto.
The latest estimate puts the exposed share at 31.2%, up from 24.8% in early 2021 and back to levels last seen in 2016.
Notably, this debate emerges even as US government-linked wallets moved substantial amounts of seized Bitcoin this week, adding another development to the debate over how large holders manage their assets.
On October 8, blockchain tracking firm Lookonchain reported that a government-linked wallet transferred 12,267 BTC, worth approximately $1.01 billion, to a newly created address. The funds were linked to Bitcoin seized from the 2016 Bitfinex hack. Separate transfers also sent approximately 9,261 BTC, valued at $770 million, to Coinbase Prime.Â
The transfers do not establish that the government sold the assets or moved them because of quantum concerns. Nevertheless, they highlight the importance of distinguishing between wallet transfers, custody arrangements and actual sales when assessing major Bitcoin movements.
Meanwhile, Schultze-Kraft's estimates suggest that 57% of Bitcoin held on centralized exchanges sits in addresses with exposed public keys, compared with 55% in May and 39% in early 2021.
Approximately 1.79 million BTC held by exchanges fall into the exposed category. The proportion varies across platforms, with estimates of 10% for Coinbase, 83% for Binance and 100% for Bitfinex.
Schultze-Kraft cautioned that the figures “should not be construed as a risk rating, a signal of solvency, or a statement about the safety of any exchange or depository.â€
Drake's warning also comes as Ethereum co-founder Vitalik Buterin questions whether artificial intelligence could weaken cryptographic systems before quantum computers become sufficiently powerful. Notably, Buterin cautioned against rushing into wallet migrations
“I don't recommend anyone scramble to move their funds to new wallets today,†he said on Thursday.
He further argued that the industry must consider potential AI-related vulnerabilities alongside quantum risks.
