The Chaincode Podcast

Rusty drops by to tell us about why privacy and robustness should be prioritized in Lightning.

We discuss:

Elle Mouton and Oliver Gugger join us to talk with us about the Simple Taproot Channel proposal.

We cover:

Alekos Filini and Daniela Brozzoni visit the podcast to discuss the Bitcoin Development Kit (BDK). Hang out with them on the BDK Discord.

We cover:

Tadge Dryja chats with us about writing the Lightning Network paper and working in the Bitcoin space.

We discussed:

Andrew Chow joins us to discuss Bitcoin Core wallet development, PSBT, Output Descriptors, and HWI.

We cover:

- Why do we need a wallet in Bitcoin Core? (0:58)

- Refactoring the Wallet codebase to build Output Descriptors (5:59)Should we rewrite the wallet? (10:30)

- Changes to Coin Selection (11:35)

- Wallet interoperability (17:10)

- Hardware Wallet Integration (HWI) (18:20)

- Partially Signed Bitcoin Transactions (PSBT) (19:01)

- Becoming Maintainer (22:06)

- Tracking the UTXO pool (23:43)

- Main components of the Bitcoin Core Wallet (26:00)

- Who uses Bitcoin Core Wallet? (27:02)

  - Survey Results

- What’s the future of the GUI? (29:21)

  - Bitcoin Core GUI

- Switch to Descriptor-based wallets (32:52)

Greg Sanders joins us to discuss ANYPREVOUT, ephemeral anchors and LN symmetry (a.k.a. ELTOO).

We chat about:

- Package relay (2:07)

- Pinning attacks (3:14)

  - BIP125

  - T-Bast’s pinning attack summary

- Mempool policy (4:56)

- Stuffing the mempool - 2017 (5:20)

- Rewrite mempool or make the problem simpler (07:57)

- Package relay RBF A.K.A. V3 (8:38)

- Reducing the standard transaction size to 65 bytes PR (14:25)

- March to LN symmetry (19:07)

- Daric: A Storage Efficient Payment Channel With Penalization Mechanism

- Two-party eltoo w/ punishment by AJ Towns

- BIP118 - SIGHASH_ANYPREVOUT (26:17)

  - SIGHASH_NOINPUT

- Softfork and activation history (28:11)

- Ephemeral anchors (32:18)

  - op_2 email by Luke

Sergi Delgado joins us to discuss Watchtowers, his prior work in Bitcoin and Lightning privacy, Python vs. Rust and the impact of Eltoo.

We cover:

- Sergi’s prior research

- Mapping Network Topology Research (02:46)

  - TxProbe paper

- An Empirical Analysis of Privacy in the Lightning Network (09:18)

  - Lightning white paper, 2016 (09:48)

  - Security and Privacy of Lightning Network Payments with Uncertain Channel Balances (13:38)

  - Episode with Sergei on Probing

  - Channel Jamming paper (13:50)

  - Episode with Clara and Sergei

- Should we pay for failed payments? (14:19)

  - HTLC withholding vs. HTLC hodling (15:48)

  - Is Lightning flawed when it comes to privacy? (16:32)

- Watchtowers (17:44)

  - Python PoC (21:49)

  - ZmnSCPxj’s writing watchtowers

  - Building on LDK (24:20)

  - Transition to rust (24:45)

- Altruistic towers vs professional services (30:21)

- More privacy considerations in Lightning (34:11)

- Monitoring and reacting paradigm (44:04)

- Storage and Eltoo (50:06)

- Professional tower revenue models - subscription vs. bounties (53:00)

We continue the conversation with Pieter Wuille and Tim Ruffing and Nesting, ROAST, Half-Aggregation, Adaptor Signatures, atomic swaps and more.

If you have not tuned into the first part of this conversation, we recommend listening to that one first.

We cover:

- Nesting (00:49)

- ROAST (12:09)

- Cross-input Signature Aggregation (18:49)

- Half-aggregation (34:32)

  - Half-Aggregation of BIP 340 Signatures and BIP340

- Adaptor signatures and atomic swaps (39:32)

Further resources:

Pieter Wuille and Tim Ruffing treat us to a conversation about Schnorr, multi-signatures, MuSig, and more. We covered a lot so this is part one of a two part conversation.

We discussed:

- When to roll your own cryptography (01:31)

- Schnorr Signatures (09:01)

  - Why is Schnorr preferable to ECDSA? (10:55)

- Schnorr efficiency improvements (15:52)

- Multisigs (23:16)

- MuSig (25:07)

  - Yannick Seurin

  - Rogue key attack or key cancellation attack (31:00)

  - Bellare-Neven (32:12)

- Interactive versus non-interactive protocols (35:30)

- FROST (42:42)

Clara and Sergei stop by to chat about their recent proposal on mitigating jamming attacks in the Lightning Network. We talk unconditional fees, local reputation, the impact on decentralization and UX, and the state of Lightning in general.

We discuss:

- What is jamming and why is it free? (03:43)

- How our jamming project started (06:44)

- Prior work on jamming (08:00)

- The desired properties of a solution (09:57)

- Reputation (12:47)

- Centralization concerns (14:17)

- Unconditional fees (19:25)

- How are unconditional fees delivered? (23:31)

- UX implications (24:45)

- Moving research results towards implementation (27:15)

- Effects on balance probing (29:21)

- Lightning as a messaging network (30:46)

- Effects on watchtowers (32:57)

- Reviews and feedback so far (34:17)

- Future research ideas (34:55)

- Privacy-preserving reputation (37:33)

Additional resources:

- Spamming the Lightning Network

- Preventing Channel Jamming

- Bitcoin Optech: Channel jamming attacks

- The impacts of channel jamming

- Bitcoin problems: Channel balance probing