Recent findings from analytics firm Glassnode highlight a significant quantum risk lurking within the Bitcoin network. Approximately 6.04 million bitcoins, representing over 30% of the total circulating supply, stand vulnerable to potential breaches by quantum computers, which have the theoretical power to undermine current cryptographic protections.
The primary concern hinges on whether the public key necessary to spend these bitcoins is already visible on the blockchain. When exposed, these public keys could be exploited, allowing future quantum computers to potentially compromise the associated funds. This exposure falls into two distinct categories: structural and operational.
Structural exposure refers to outputs inherently revealing their public keys due to the script types used, mostly prevalent in Bitcoin’s early years when wallet security standards were less advanced. This category now comprises about 1.92 million BTC, approximately 9.6% of the total supply. Operational exposure, however, involves coins initially protected but whose public keys became visible through address reuse, partial spending, or custody practices. This risk segment accounts for roughly 4.12 million BTC, or 20.6% of the supply, and has notably grown over recent years despite progress in wallet technology.
These trends outline a complex landscape where early Bitcoin adoption and user habits contribute significantly to the ongoing quantum threat. Meanwhile, the remaining supply—around 14 million bitcoins—is considered quantum-safe due to keys remaining undisclosed on-chain.
The pace of quantum computing development has intensified discussions in the cryptocurrency sector about securing assets against future attacks. While practical quantum computers capable of breaking Bitcoin’s cryptography do not currently exist, the visibility of public keys on-chain creates a pre-emptive vulnerability that cannot be ignored.