TLDR
- BIP-360 adds a quantum-resistant address type called Pay-to-Merkle-Root.
- About 6.51 million BTC are said to sit in addresses open to quantum attacks.
- Satoshi’s estimated 1 million BTC remain in early P2PK outputs with exposed public keys.
- Hourglass V2 would limit P2PK spending to 1 BTC per block over many years.
Bitcoin developers are moving new proposals as concerns grow over future quantum computing threats. The debate now centers on old Bitcoin holdings, including Satoshi Nakamoto’s estimated 1 million BTC.
A new proposal, BIP-360, has entered the official BIP repository. It introduces a quantum-resistant address type called Pay-to-Merkle-Root, or P2MR. At the same time, developers are discussing how to handle coins held in older address formats.
BIP-360 adds a new path for safer Bitcoin storage
BIP-360 proposes a new address type designed to resist quantum attacks. The goal is to give users a way to move funds into a format that offers stronger protection if quantum systems improve.
The proposal comes as developers assess how much Bitcoin could be open to that risk. Estimates in the debate place about 6.51 million BTC in older address types that may be easier to target in a quantum attack.
Satoshi Nakamoto’s coins are central to the debate because many are tied to early Pay-to-Public-Key outputs. In that format, the public key is already exposed, and that can create a larger risk if quantum computing reaches a usable stage.
These coins have not moved, but their size makes them important to the market. Any forced movement or theft could place a large amount of Bitcoin into circulation in a short time.
Legacy coin freeze proposal sparks debate among developers
A separate proposal linked to Jameson Lopp would freeze coins in legacy addresses if they fail to move to safer formats before a deadline. That idea has caused debate because some developers see it as a protective step, while others see it as too aggressive.
Critics argue that freezing old coins could change long-standing expectations around ownership. Supporters say the network should act before a practical quantum threat appears and before exposed coins become easy targets.
The debate is sharper in the case of Satoshi’s holdings because of their scale. Around 1 million BTC in one vulnerable class of outputs creates a unique problem for Bitcoin if those coins are ever taken.
No final path has been agreed, and discussion remains active. Developers are weighing user choice, market stability, and the need to protect coins that remain in old formats.
Hourglass V2 aims to slow any rush of stolen P2PK coins
Bitcoin developer Hunter Beast has proposed Hourglass V2 as another option. The proposal would limit Pay-to-Public-Key outputs used in transaction inputs to 1 BTC per block.
It would also stop the creation of new P2PK outputs for addresses not already being spent. In addition, no P2PK outputs could be created from other output types under the proposed rules.
Beast said the plan is meant to reduce sell pressure if quantum attackers gain access to old P2PK coins. Without limits, thousands of P2PK transactions could be included in a block, allowing a very large release of coins.
The proposal says that more than 300,000 BTC could reach the market in one block under an unrestricted scenario. Under Hourglass V2, that flow would fall to about 144 BTC per day.
Proposal focuses on Satoshi-era outputs while wider risks remain
Hourglass V2 applies only to P2PK outputs, not all address types that may face quantum risk. The reason given is that many other output types remain in common use, and tighter rules there could disrupt migration.
That narrow scope keeps attention on Satoshi-era coins and other older P2PK holdings. Under the proposal’s estimates, moving all P2PK coins would take more than 32 years.
The draft also says original keyholders could still move their coins after activation. That would remain possible unless a quantum attacker is already competing for those same outputs.
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