The core developers of Bitcoin have introduced an innovative proposal named Pay-to-Merkle-Root (P2MR) to the Bitcoin Improvement Proposal repository. This move, which has garnered considerable attention within the cryptocurrency community, is yet to see implementation in any Bitcoin node, and no timeline has been announced for its rollout.
What sets P2MR apart from Taproot?
Unlike the existing Taproot system, which facilitates fund transfers either via direct signature or a script with a Merkle proof, P2MR adopts a different approach. It dispenses with the key-path, instead connecting outputs directly to a script tree’s Merkle root. Consequently, every transaction must reveal the corresponding script and provide a Merkle proof, leading to larger transaction sizes and higher fees compared to Taproot.
Is Bitcoin ready for quantum computing threats?
Bitcoin’s vulnerability to future quantum computing threats is a growing concern. The new BIP-0360 proposal explores this by considering two main attack models. Long-term attacks could potentially exploit the weaknesses of publicly visible keys, while short-term attacks demand far quicker execution. Though P2MR seeks to mitigate long-term threats, it provides modest defense against short-term risks.
The transition to P2MR would not be immediate. Its integration requires thorough deliberation and coordination across various stages. If adopted, a new format, possibly starting with “bc1z,” for P2MR addresses would be introduced, focusing on reducing quantum vulnerabilities. Taproot outputs would still be functional, and existing Taproot transactions wouldn’t benefit from the new protections.
Opting for P2MR would be a choice, not a mandate. Security-conscious users, particularly large asset holders and custodial enterprises, might welcome this additional layer of security. However, for everyday Bitcoin users, considerations like increased transaction sizes, heightened fees, and possible privacy constraints could deter adoption.
To proceed with the activation, Bitcoin’s diverse network stakeholders must reach a consensus. Additionally, P2MR’s continued relevance will depend on the development of standards for post-quantum signature algorithms, requiring seamless Bitcoin protocol integration.
Technically, P2MR builds upon Taproot’s flexible framework, enabling advanced functionalities like multisignature arrangements, time-locked vaults, and smart contracts. Isabel Foxen Duke, one of the key contributors, has emphasized the importance of transparency in conveying these complexities to both core developers and the public.
“Our goal is to make the concept of quantum readiness clear and understandable for everyone involved in the Bitcoin space,” remarked Duke.
While recent progress in cryptographic research sheds light on post-quantum signatures and quantum computing capabilities, several years of discourse, development, and testing lie ahead before a decision on P2MR’s integration into Bitcoin’s main structure is reached.
