The unsuitability of presigned transactions for vaults

The discourse surrounding the implementation and practicality of vault-like constructions in cryptocurrency, particularly Bitcoin, involves several key projects and concepts. Among these, Revault, Liana, and Bryan Bishop's prototype code (prototype code) are notable for their approaches to enhancing security against theft and loss. Liana, distinct from Revault, does not aim to emulate a traditional vault but rather introduces an additional, timelocked spending path to protect against loss. This mechanism resembles the functionality of Green wallet but could benefit from implementing a covenant, like TLUV, to prevent issues related to timelock expiration without necessitating users to rotate their coins.

There has been discussion on whether current scripting capabilities can effectively implement vaults or if something like an OP_VAULT operation is required. The conversation extends to the use of covenants and the potential for emulating them using trusted oracles, though this raises concerns about single points of failure (SPOF) which are particularly critical in vault designs. Despite these discussions, there appears to be a lack of minimal viable products (MVPs) that utilize vaults with emulated covenants, indicating either a gap in development or a lack of interest.

The Revault project exemplifies a design closest to achieving the goals of a vault without necessarily requiring a covenant. However, it faces challenges in ensuring security and operational integrity, such as verifying that all watchtowers have received necessary signatures for cancel transactions before proceeding with unvault transactions. This verification process is crucial for handling significant amounts, suggesting that the implementation of a simple covenant could make the transaction process more secure and atomic. Despite pausing development due to these challenges and a perceived lack of serious interest, the dialogue suggests that the community remains undecided on the overall demand for vaults.

Additionally, there's a technical note regarding the use of Child Pays for Parent (CPFP) versus sighash flags for managing transaction dependencies and malleability issues. The discussion indicates that without Addressable Payout Outputs (APO), a single malleated transaction ID could compromise all funds, highlighting the complexities and technical considerations in developing secure, efficient vault-like solutions in the cryptocurrency space.