Author: Christopher Allen 2021-04-12 18:45:27
Published on: 2021-04-12T18:45:27+00:00
Christopher Allen, a member of Blockchain Commons, has proposed best practices to avoid xpub reuse and improve privacy in Bitcoin multisig accounts. While he agrees that the problem needs to be solved, he does not think the current solution is effective. Instead, he suggests a multi-round cryptographic commitment scheme similar to musig threshold signatures with Taproot/Schnoor. In the meantime, he proposes several measures to improve privacy for stateful wallets, such as accepting that users must backup their multisig account maps and cosigner key material to recover funds. He also recommends that cosigner wallets and transaction coordinator services should not share the master xpub and that the master xpub fingerprint should not be used. Instead, a single parent fingerprint should be offered for each account, and a transaction coordinator should accept different fingerprints or derivations. Additionally, transaction coordinators should send the cosigner "policy" and final "account map" to all the cosigner wallets, allowing them to reject PSBT requests that do not match the original account map. These best practices are currently possible with new generation multisig hardware and software wallets, such as Foundation Devices, CoboVault, Sparrow, Bluwallet, and Gordian reference wallet tools.
Updated on: 2023-06-14T17:25:24.219467+00:00