Improving JoinMarket's resistance to sybil attacks using fidelity bonds



Summary:

In a recent Bitcoin-dev post, Dmitry Petukhov described a shared ownership rent scheme. In this scheme, the 'TXO rentier' has a signed timelocked 'backout' transaction that spends the locked TXO and assigns the reward to the rentier. However, if any transaction spends any TXO in the bond, ignoring the timelock, then the bond is invalidated when presented to takers. The rentier can therefore revoke the bond by publishing this transaction, although not on the blockchain. Takers can verify the transaction validity with relaxed rules that ignore the timelock. After verification, takers mark the entire bond as revoked and will not consider it when choosing makers.The backout transaction may not be timelocked itself but could depend on another timelocked transaction made specifically to avoid the backout transaction being timelocked. To account for this possibility, takers would need to use more relaxed verification rules or check the entire package of dependent transactions in which the last one spends the bond.


Updated on: 2023-06-13T20:21:47.311930+00:00