Postdoc Researcher Sergei joins Murch and Jonas to talk about channel balance probing in Lightning, privacy concerns in general, and the importance of researcher-developer collaboration.

We discuss:

- Sergei's background (1:50)

   - Sergei's homepage with links to all prior research

- Lightning basics (2:50)

- Why LN payments fail (3:40)

- Why privacy is important (5:30)

- Privacy potential of Lightning vs L1 Bitcoin (6:40)

- How probing works (8:40)

- Why is balance discovery bad? (11:30)

- Persistent identities in Lightning (13:00)

- Multi-vector security model and trade-offs (17:45)

- "Twitter for your bank account" meme (20:20)

- The danger of overestimating Bitcoin's privacy (21:00)

- Lightning integrations and walled gardens (22:00)

- Lightning Service Providers and LN's centralized topology (23:05)

- LNBIG booth in El Salvador (25:30)

- Potential oligopoly of large nodes (27:15)

- Probing parallel channels (28:30)

  - Analysis and Probing of Parallel Channels paper

- Combining probing with jamming (33:00)

- The limit on in-flight payments (36:00)

  - StackExchange answer about transaction size limit

- Bad and good probing (41:20)

- Countermeasures and reputation (44:00)Overview of anti-jamming measures

- Hub-and-spoke terminology and aviation analogy (49:00)

- Doing research in Bitcoin and Lightning (53:10)

- Why Bitcoin is unique (55:10)

- Researcher-developer collaboration (58:00)

Related research:

- On the Difficulty... -- the first paper about LN balance probing

- An Empirical Analysis paper about three LN attack vectors including probing

- Counting Down Thunder paper about timing attacks

- Congestion Attacks paper about jamming

- Cross-layer Deanonymization paper about linking L1 and L2

- Flood & Loot paper about malicious fee negotiation strategies

- Hijacking Routes paper about adversarial fee undercutting

Thanks to Justin for the sound engineering.