Coinbase is calling for Bitcoin's post-quantum migration to begin immediately, arguing that the ecosystem needs years to adapt before quantum computers become powerful enough to threaten current cryptography.
The cryptocurrency exchange, which controls approximately 5% of Bitcoin supply through its custody arm, published a blog post emphasizing the urgency of early preparation. "Bitcoin consensus changes and ecosystem migrations can take years, so it is important that we begin this work now," Coinbase stated.
The Quantum Threat
Current blockchain security relies on elliptic curve cryptography (ECC) and ECDSA signatures, which would be vulnerable to a cryptographically relevant quantum computer (CRQC). Google researchers have suggested such a computer could exist by 2029, while the U.S. government has set a target of making all technology systems quantum-proof by 2035.
Bitcoin transactions require private keys to authorize transfers. However, when users spend bitcoin, public keys are exposed on the blockchain. Powerful quantum computers could reverse-engineer these public keys to generate corresponding private keys, potentially allowing attackers to steal funds.
Proposed Solutions
Coinbase has outlined several technical approaches to address the quantum threat. The exchange proposed introducing post-quantum signature systems through new address types such as Pay-to-Mast-Root (P2MR) or P2TRv2.
The firm also recommended a hybrid configuration that would allow users to spend bitcoin using either classical keys or post-quantum keys during the transition period. To reduce forgery risks, Coinbase suggested implementing stateless post-quantum signatures.
Coinbase noted that the challenge of handling dormant, lost, or late-transitioning bitcoin should be addressed separately to prevent delays in the broader migration process.
Quantum Risk Assessment
According to Glassnode data, approximately 21.5% of the total Bitcoin supply is exposed to quantum risk due to address reuse, which reveals public keys on the blockchain. Additionally, about 3.5 million bitcoin, representing 17% of the supply, is considered inaccessible or lost.
Industry Momentum
Coinbase is developing a quantum-safe custody system called PQ-CoreKMS, planned for deployment next year, and intends to support various post-quantum signature standards. Other projects, including Project Eleven, are also developing similar quantum-resistant custody solutions.
