Bitcoin Developers Propose Freezing Legacy Coins to Counter Quantum Threat
A group of Bitcoin developers, led by Jameson Lopp, introduced BIP-361 to address potential quantum threats. Specifically, the proposal outlines a plan to phase out legacy cryptographic signatures. As a result, coins that fail to migrate to quantum-resistant addresses within about five years could become frozen.
Notably, the proposal titled “Post Quantum Migration and Legacy Signature Sunset” targets more than one-third of all bitcoin in circulation. In particular, it includes roughly 1 million BTC associated with Satoshi Nakamoto, whose public keys are already exposed. Meanwhile, no activation timeline has been finalized, and the proposal has already divided the community. On one side, some prioritize proactive security, while others emphasize the inviolability of ownership rights.
A Three-Phase Transition Plan
To build on earlier efforts, BIP-361 expands on BIP-360, which introduced a quantum-resistant format known as pay-to-Merkle-root. However, while that earlier update protects new outputs, it leaves about 6.9 million BTC in older address types exposed.
The new proposal therefore introduces a three-phase transition. First, Phase A would begin roughly three years after activation and block new transactions to vulnerable addresses, although users could still spend existing funds. Next, Phase B would arrive around five years after activation and invalidate ECDSA and Schnorr signatures at the consensus level. Consequently, coins in legacy addresses would become permanently unspendable. Finally, an optional Phase C could allow recovery through zero-knowledge proofs linked to seed phrases, although this step depends on further research.
“Before a quantum assault, it’s impossible to ascertain the attacker’s intentions,” the authors wrote. “An economically driven attacker will strive to stay hidden for as long as feasible, while a malicious actor will seek to cause maximum destruction”.
Debate Over Security and Ownership
Unsurprisingly, the proposal has sparked intense debate. Critics argue that Phase B could effectively lock billions of dollars in dormant wallets, including holdings linked to Satoshi Nakamoto. Therefore, they describe the plan as confiscatory and warn it could set a troubling precedent.
On the other hand, supporters contend that a quantum-enabled theft would cause far greater harm than a controlled freeze. In their view, preserving a recovery pathway outweighs the risks of inaction. At the same time, Adam Back has noted that current quantum technology still lacks the scale needed for a real threat. Consequently, he frames the issue as a long-term concern rather than an immediate crisis.
Nevertheless, the proposal’s authors point to recent findings from Google Quantum AI, which suggest that breaking elliptic curve cryptography may require fewer resources than previously believed. As the discussion continues, the central question remains whether decentralized governance can achieve consensus on early action, or if the network will wait until the threat becomes more imminent.
