Quantum Sunset Economics: a working paper analyzing PACT adoption

The newly added Section 3.8 in the discussion about xpub disclosure emphasizes that the value exposed to quantum threats might be underestimated when considering only on-chain data. This underestimation occurs because xpubs, when leaked or shared, reveal all derived addresses within a disclosed branch, including those that have never engaged in transactions. Such exposure extends beyond simple transactional history, encompassing potential vulnerabilities across all associated addresses.

Moreover, the discussion highlights the particular vulnerability of institutions to xpub disclosures. These entities are often intertwined with custodial and reporting duties—exactly the type of relationships from which xpub leaks frequently emerge. Consequently, the argument is made for these institutions to adopt centralized pooling services. Such services could mitigate risks by centralizing and securing key information away from the public sphere, thus reducing the likelihood of such leaks.

The critique of the xpub mechanism as inherently flawed due to its semi-public nature—a hybrid in the dichotomy of public vs. private keys in asymmetric cryptography—is also notable. The xpub's design is seen as a compromise between convenience and security, a trade-off that has been questioned since its inception. Historical concerns about privacy violations and security threats due to xpub sharing reflect ongoing apprehensions regarding its adequacy in safeguarding user data against potential quantum computing threats. This analysis underscores the need for heightened awareness and revised practices concerning xpub management and security within cryptographic and institutional frameworks.