Bitcoin developers and researchers have introduced a new proposal, BIP-361, aimed at protecting the network from future quantum computing threats by restricting access to vulnerable legacy addresses.
The proposal targets older Bitcoin address types, particularly Pay-to-Public-Key (P2PK) formats, where public keys are already exposed on-chain.
These addresses are considered highly susceptible to potential quantum attacks, as advanced quantum computers could theoretically derive private keys from exposed public keys and gain unauthorized access to funds.
BIP-361 outlines a phased approach to mitigating this risk. In its initial stage, the proposal would prevent users from sending funds to quantum-vulnerable addresses, encouraging migration toward safer, post-quantum address types.
In later phases, it suggests invalidating legacy cryptographic signatures such as ECDSA and Schnorr for these addresses, effectively freezing funds that remain unmigrated.
The proposal builds on earlier efforts like BIP-360, which introduced new quantum-resistant address formats designed to reduce exposure to cryptographic attacks.
These initiatives reflect growing concern within the Bitcoin community about long-term risks posed by quantum computing advancements.
Quantum threats primarily target public-key cryptography, which underpins Bitcoin’s security model.
While current systems remain secure against classical computers, sufficiently powerful quantum machines could eventually break these cryptographic assumptions.
According to estimates, a significant portion of Bitcoin, potentially up to 30%, resides in addresses with exposed public keys, making them vulnerable in a post-quantum scenario.
Critics of BIP-361 argue that freezing funds, especially those in early addresses such as those potentially linked to Bitcoin’s creator, could be controversial and raise questions about immutability. Supporters, however, see it as a necessary trade-off to preserve network security.
The proposal remains under discussion and has not been adopted. Like all Bitcoin Improvement Proposals, it must undergo extensive review and consensus before any implementation.
