The Chaincode Podcast

Latest Episodes:

Chaincode Decoded: Blockchain - Episode 14 May 27, 2021

Show notes

In this Chaincode Decoded segment we talk about the fundamental role of Bitcoin's blockchain and some of its peculiarities.

We discuss:

Purpose of the blockchain (0:40)

Mining is a lottery, not a race (1:57)

Why doesn't the same miner always win? (5:12)

What happens if two blocks are found at the same height? (6:12)

The longest reorgs (9:11)
How does the blockchain work? (12:18)
- Headers-first synchronization and Ultraprune: Episode 1 with Pieter Wuille
- Episode 5: The UTXO set
Why does Bitcoin converge on one chain? (15:20)
- Selfish mining paper: Majority is not Enough: Bitcoin Mining is Vulnerable
Will we always find a new block? (18:04)
- Entropy sources in the block header
Mining pools have disjoint hashing spaces (19:30)
- Correction: mining pools do not have a separate pay-out address for each participant, but give out a unique coinbase transaction stub for each.
- Eschaton block

Thanks to Caralie for the sound engineering.

Matt Corallo and Lightning Development Kit - Episode 13 May 13, 2021

Show notes

In Episode 13, we sit down again with Matt Corallo and discuss his work on the Lightning Development Kit (LDK).

In this conversation we cover:

- Starting Rust-Lightning (1:20)

- Language bindings challenges (4:09)
- FFI (5:32)

- Interoperability of Lightning (7:10)

- Zero-value invoices (7:35)

- Keysend/push payments/spontaneous payments (8:20)

- What is the LDK stack? (9:29)

- Anchor Outputs (10:41)
- Child pays for parent (CPFP) (11:02)

- Who tracks the onchain state when using LND? (12:30)

- LDK tracks the channel commitment transaction, how is that done? (13:45)
- Compact block filters

- Contrasting multiple implementations working from a spec in Lighting vs. no spec with one dominant reference implementation in Bitcoin (14:58)
- The Lightning Spec

- What's the state of the Lightning Network? Have we moved beyond #reckless? (18:49)
- Denial of Service (DoS) vulnerabilities
- Channel Jamming (22:00)

- Eltoo and the punishment dynamic (22:45)

- Will the network trend to trusted relationships and lend itself to KYC? (24:50)

- FATF updates its guidance on Virtual Asset Service Provider (VASP) (26:50)

- Where LDK goes from here? (29:55)

Thanks to Caralie for the sound engineering.

Chaincode Decoded: Mempool - Episode 12 Apr 26, 2021

Show notes

The Chaincode Decoded segment returns and we jump into the deep end of the mempool.

Child Pays for Parent (CPFP) (2:15)
How miner evaluate fee rates (4:34)
Why is it hard to estimate fee rates? (6:03)
How do exchanges estimate fees? (8:00)
Will the mempool empty again? (9:23)
Miner/pools and the need for a high fee environment (11:04)
Replace by Fee (RBF) (14:05)
- BIP 125
Mempool eviction and the problems it can cause (19:04)
Anchor Outputs (20:50)
Package Relay (21:06)
Ways to use the blockspace more efficiently (22:15)
- blockchain.com implements Segwit

Thanks to Caralie for the sound engineering.

Chaincode Decoded: Bech32m - Episode 11 Apr 16, 2021

Show notes

This revisits a segment we call Chaincode Decoded. In this episode, we'll learn how to say Bech32 and also what it and Bech32m are. Enjoy!

Correction: The characters removed from the set are 1 B I O (2:20)

Why do we need Bech32? (0:57)
What is the distinction between Bech32 and native SegWit? (3:20)
Why does Taproot need a new address format? (4:13)
Bech32 length extension mutation weakness (11:20)
- mailing list post
Bech32m (12:25)
- BIP350

Further resources:

Thanks to Caralie for the sound engineering.

Carl Dong and Modularizing the Bitcoin Consensus Engine - Episode 10 Dec 15, 2020

Show notes

In part 2 of this sit down with Carl Dong, Murch and Jonas cover the delicate work of modularizing the Bitcoin consensus engine.

In this conversation, we cover:

- Carl's De-globalize ChainstateManager PR (2:25)

- Async Block Processing PR

- Deglobalize class of chainstate manager (g_chainman) (3:40)

- AssumeUTXO

- global variables and main (5:25)

- scripted diff (9:35)

- 0.8 upgrade consensus failure (11:25)

- Jorge Timon's libconsensus project (13:10)

- current libbitcoinconsensus only does script verification (13:25)

- the case for multiple implementations (14:40)

- ABI (15:10)

Thanks as always to Matthew Zipkin for the sound engineering.

Carl Dong and Build Systems - Episode 9 Nov 30, 2020

Show notes

In part 1 of this sit down with Carl Dong, Murch and Jonas get into the weeds of all things build system. Stay tuned for the second half of this conversation when Carl describes his recent adventures isolating the libconsensus engine.

In this conversation, we cover:

- GUIX (2:25)
- talk at 2019 Breaking Bitcoin about reproducible builds

- Gitian builds (4:15)

- Fake time (4:50)

- Timestamps and reproducibility of packages (6:33)

- reproducible-builds.org (6:57)
- SOURCE_DATE_EPOCH

- Toolchains (14:40)

- Windows Builds and reproducibility (15:20)
- GCC libtool pointer confusion

- NSIS (20:25)

- Using Debian as an example (22:56)

- User choice in their security model (28:15)

- Making the process accessible (31:20)

- Mac OS X Toolchain & SDK and cross-compiling (33:30)

Thanks as always to Matthew Zipkin for the sound engineering.

Murch and Enterprise Wallets/UTXO Management - Episode 8 Nov 09, 2020

Show notes

After a long hiatus, we return to talk with new Chaincode member Murch and get his take on enterprise wallets and UTXO management.

In this conversation, we cover:

- Enterprise UTXO management (3:35)

- The impact of the 2017 hype cycle (4:30)

- The importance of UTXO set minimization (5:30)

- The fee market today (6:44)

- Batching Transactions (9:15)
- Payment Batching

- Consolidations (11:05)
- Consolidation of 4 Million UTXOs at Xapo

- Change splitting (14:10)

- Replace By Fee (16:04)
- RBF in the wild
- Fee bumping

- SegWit (21:10)

- How enterprises estimate fees (25:00)

- Omnibus wallets (28:05)

- Off-chain sending (31:50)

- Taproot (33:57)

Other resources:

- Bitcoin Optech Field Report: How segwit and batching could have saved half a billion dollars in fees

Thanks as always to Matthew Zipkin for the sound engineering.

Nadav Kohen and Payment Points - Episode 7 Mar 30, 2020

Show notes

In Episode 7, we chat with Nadav Kohen of Suredbits and discuss payment points as an alternative to HTLCs on the Lightning Network.

In this conversation we cover:

Payment points (1:55)
- Blog post part 1
- HTLCs (2:00)
Timelocks (4:16)
HTLC drawbacks (5:38)
- Payment decorrelation
- Wormhole attack presented in Anonymous Multi-Hop Locks for Blockchain Scalability and Interoperability (6:35)
Point time lock contracts (PTLCs) (9:50)
- Adaptor signatures on Schnorr
Proof of payment (13:25)
Invoiceless transactions (15:05)
Hashes, pre-images, and HTLC mechanics (16:35)
Onion analogy (18:55)
PTLC mechanics (19:30)
Why don’t we use PTLCs today? (22:15)
Lightning in Scriptless Scripts posting by Andrew Poelstra March 2017
Improving proof of payment (26:10)
Stuckless payments (30:46)
Spam on Lightning (35:46)
Selling Signatures and Schnorr signatures off the main chain (36:55)
Contingent payments (39:20)
Escrow contracts (41:28)
Atomic multiparty setup and payment renegotiation (46:02)
ETA of payment points (48:02)

Thanks as always to Matthew Zipkin for the sound engineering.

Matt Corallo and Compact Blocks/FIBRE - Episode 6 Mar 12, 2020

Show notes

In Episode 6, we sit down with Matt Corallo and discuss his work on compact blocks and the FIBRE network.

In this conversation we cover:

Selfish mining (2:03)
- Majority is not Enough: Bitcoin Mining is Vulnerable
- Optimal Selfish Mining Strategies in Bitcoin
Ethereum's larger pools making superlinear profits (5:10)
Defining selfish mining (9:52)
Compact blocks (12:37)
- FAQ
- BIP152
- Reference implementation
FIBRE (20:28)
Forward error correction (24:14)
- Shamir secret sharing
Difference between TCP and UDP (29:21)

Thanks as always to Matthew Zipkin for the sound engineering.

Chaincode Decoded: The UTXO Set - Episode 5 Feb 26, 2020

Show notes

This is our first Chaincode Decoded Podcast. In this new podcast format, we'll dive into the details of a concept we've talked about on previous shows. No guests, no news, just Jonas and John talking about Bitcoin. A podcast by Bitcoin nerds for Bitcoin nerds.

In the first episode, we talk about the UTXO set. We'd love to know what you think!

Ultraprune - episode 1 (1:20)

Assume UTXO - episode 4 (1:28)

The cache layer (8:02)

Dbcache parameter (9:48)

- John talks about latency comparisons on a human scale. (Note: He incorrectly says that 1 second for RAM access equates to "months or years" for disk access. Actually 4 minutes for RAM access equates to 1-9 months for disk access.)

Different ideas on how to keep track of the UTXO set (11:29)

- utreexo (13:48)

What’s the future of the size of the UTXO set? (13:54)

UTXO consolidation (15:02)

UTXO selection (16:48)

H/T to Amiti for the idea of the format. Thanks as always to Matthew Zipkin for the sound engineering.