Many Bitcoin addresses are presumed to belong to the pseudonymous creator, Satoshi Nakamoto, or to individuals who have lost their private keys, meaning those coins are effectively locked and cannot be transferred safely. An additional five million or so addresses are at risk due to address reuse, a finding reported by Project11, a research group that tracks this problem. Most of these exposed addresses are believed to be active holdings in exchange wallets.
Replacing Bitcoin’s current cryptographic signatures with quantum‑resistant alternatives may be straightforward, but the real challenge lies in the coins that remain unmoved. One group advocates for a strict deadline: beyond this date, the existing signature schemes—ECDSA and Schnorr—would no longer be considered valid, rendering any unmigrated coins unspendable. They argue that leaving these coins online would effectively hand a sizable stash of Bitcoin to a malicious actor, such as a sanctioned state, potentially destabilizing the market and undermining the network’s integrity.
Opponents view this approach as a confiscatory act that violates the property rights foundational to Bitcoin, warning that it could set a dangerous precedent for future government‑driven freezes of cryptocurrency holdings.
CoinDesk has documented several proposals that sit between these two positions over the past two months.
The Hourglass proposal would limit the number of vulnerable coins that could be spent per block, thereby preventing a sudden influx in supply. BIP‑361, developed by Jameson Lopp and others, allows holders who have migrated to demonstrate ownership after the cutoff through a quantum‑resistant proof that reveals no private key. PACTs, introduced by Paradigm’s Dan Robinson, enable owners to timestamp a private claim now and transfer their funds at a later date without exposing any sensitive information at present.