Get Me Out of This Payment! Bailout: An HTLC Re-routing Protocol

Oğuzhan Ersoy*, Pedro Moreno-Sanchez, Stefanie Roos

*Corresponding author for this work

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientificpeer-review


The Lightning Network provides almost-instant payments to its parties. In addition to direct payments requiring a shared payment channel, parties can pay each other in the form of multi-hop payments via existing channels. Such multi-hop payments rely on a 2-phase commit protocol to achieve balance security; that is, no honest intermediary party loses her coins. Unfortunately, failures or attacks in this 2-phase commit protocol can lead to coins being committed (locked) in a payment for extended periods of time (in the order of days in the worst case). During these periods, parties cannot go offline without losing funds due to their existing commitments, even if they use watchtowers. Furthermore, they cannot use the locked funds for initiating or forwarding new payments, reducing their opportunities to use their coins and earn fees. We introduce Bailout, the first protocol that allows intermediary parties in a multi-hop payment to unlock their coins before the payment completes by re-routing the payment over an alternative path. We achieve this by creating a circular payment route starting from the intermediary party in the opposite direction of the original payment. Once the circular payment is locked, both payments are canceled for the intermediary party, which frees the coins of the corresponding channels. This way, we create an alternative route for the ongoing multi-hop payment without involving the sender or receiver. The parties on the alternative path are incentivized to participate through fees. We evaluate the utility of our protocol using a real-world Lightning Network snapshot. Bailouts may fail due to insufficient balance in alternative paths used for re-routing. We find that attempts of a node to bailout typically succeed with a probability of more than 94% if at least one alternative path exists.

Original languageEnglish
Title of host publicationFinancial Cryptography and Data Security - 27th International Conference, FC 2023, Revised Selected Papers
EditorsFoteini Baldimtsi, Christian Cachin
Number of pages18
ISBN (Print)9783031477508
Publication statusPublished - 2024
Event27th International Conference on Financial Cryptography and Data Security, FC 2023 - Bol, Croatia
Duration: 1 May 20235 May 2023

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference27th International Conference on Financial Cryptography and Data Security, FC 2023

Bibliographical note

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project
Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.


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