A new Bitcoin Improvement Proposal, or BIP, has introduced a structured plan to transition the network away from address types that could be at risk if quantum computing advances enough to compromise today’s cryptography.
A group of Bitcoin developers, led by cypherpunk Jameson Lopp, on Tuesday introduced a draft proposal on GitHub titled “Post Quantum Migration and Legacy Signature Sunset,” registered as BIP-361.
The draft suggests a multi-stage migration. Initially, this migration would stop users from sending funds to older, vulnerable address types. Later, it would make some legacy signature-based spends invalid.
How the phased sunset would work
BIP-361 proposes a three-phase plan that is well organized to guide the transition.
In Phase A, users would no longer be able to send Bitcoin to older address types that could be exposed to quantum attacks. Instead, coins could only be moved from those older formats into new post-quantum addresses.
According to the draft, this stage would start 160,000 blocks after activation, which is roughly three years later.
Phase B would be a lot more intense. At a pre-set block height, Bitcoin nodes would reject transactions that rely on Elliptic Curve Digital Signature Algorithm (ECDSA) or Schnorr keys, which are the signature systems widely used in Bitcoin today.
The draft would put that step two years following Phase A. Combined, the schedule would see the hardest cutoff coming into effect about five years after activation.
Phase C is still under research. It may offer a backup way for users who do not move their funds on time. One idea is to use zero-knowledge proofs (ZKPs) to show that a person owns the BIP-39 seed phrase linked to an old address.
If that works, users may be able to recover their funds in a quantum-safe way without exposing private keys. Still, this part is not final and would need separate approval.
Developers push early action to reduce quantum risk
The authors argue that Bitcoin should not wait until quantum computers become an immediate danger.
They noted that the network needs a public timeline now because wallets, exchanges, miners, and custodians usually take years to coordinate around major technical changes.
They also argue that uncertainty itself creates risk, while a fixed transition plan gives the ecosystem a clear target.
“Coordinating distributed groups is more prone to delay, even if everyone has similar motivations. Historically, Bitcoin has been slow to adopt code changes, often taking multiple years to be approved.” developers noted.
The draft highlights several reasons for urgency. It states that over 34% of all bitcoin had shown a public key on-chain as of 1 March 2026. This makes those coins potential targets for a future quantum attacker with sufficient power.
Additionally, BIP-361 references outside estimates suggesting that a cryptographically relevant quantum computer could emerge between 2027 and 2030.
BIP-361 stands out because it takes a tougher approach. Instead of leaving older Bitcoin addresses at risk forever, the draft proposes shutting them down step by step.
It gives users time to upgrade early and may still offer a recovery path in Phase C. Miners, exchanges, and large holders also benefit because a quantum attack could hurt Bitcoin’s price and security.
BIP-361 is not final and would require wide acceptance by the Bitcoin community before it could progress.
Developers, researchers and other stakeholders are in the process of debate over the proposal. If it gains approval, it could become one of Bitcoin’s clearest early steps to prepare for future quantum-related risks.
Quantum threat concerns grow
Recent research has added to concerns about Bitcoin’s long-term security. Google researchers cautioned that next-generation quantum computers will be able to crack the encryption of Bitcoin and other digital systems even earlier than many anticipated.
They said this could happen around 2029 if progress keeps moving at the current speed.
Another update from the California Institute of Technology (Caltech) and Oratomic raised similar concerns. Their scientists claimed that a fault-tolerant quantum computer could require only 10,000 to 20,000 qubits, significantly less than earlier estimates of millions.
They said that such a lower threshold would allow useful quantum machines by the close of this decade.
Tron has also started building quantum-resistant security to protect its blockchain early. Founder Justin Sun said Tron is taking action while Bitcoin debates freezing vulnerable addresses and Ethereum focuses on research.