# Abstract In the case of custodial bitcoin vault, security of user funds depend on the trusted signers of the multi-sig. Unlike lightning, vaults do not provide the user with a commitment/exit transaction to guarantee deposited satoshis back. Boomerang proposes a fragmented reserve design with an escape hatch to prevent loss of funds, when signer liveness is compromised. While a similar design proposal exists \[[link](https://github.com/kanzure/python-vaults)] for a personal vault which clawbacks to a secure cold wallet, Boomerang is designed for a distributed network to relay bitcoin without a centralised clawback and instead rely on a refund transaction to all the depositors. Along with an escape hatch, Boomerang relies on relay capacity of each Fragment, which is estimated to be 1% of the total reserve value deposited in the individual fragments. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.twilight.org/boomerang/abstract.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.