Bitcoin, Explained — The Technical Side of Bitcoin

In this episode of The Van Wirdum Sjorsnado, hosts Aaron van Wirdum and Sjors Provoost discuss the basics of the Lightning Network, Bitcoin’s Layer 2 protocol for cheaper, faster and potentially more private transactions.

In this episode of The Van Wirdum Sjorsnado, Aaron and Sjors discuss why it matters that Bitcoin software is open source… and why even open source software doesn't necessarily solve all software-specific trust issues.

In theory, the fact that most Bitcoin nodes, wallets and applications are open source should ensure that developers can’t include malicious code in the programs: anyone can inspect the source code for malware. In practice, however, the number of people with enough expertise to do this is limited, while the reliance of some Bitcoin projects on external code libraries (“dependencies”) makes it even harder.

Furthermore, even if the open source code is sound, this doesn’t guarantee that the binaries (computer code) really correspond with the open source code. Aaron and Sjors explain how this risk is largely mitigated in Bitcoin through a process called Gitian building, where several Bitcoin Core developers sign the binaries if, and only if, they all produced the exact same binaries from the same source code. This requires special compiler software.

Finally, Aaron and Sjors discuss Guix, a relatively new project that goes above and beyond the Gitian process, to minimize the level of trust required to turn source code into binaries — including trust in the compiler itself.

In this episode of The Van Wirdum Sjorsnado, hosts Aaron van Wirdum and Sjors Provoost discuss RSK’s shift from a federated sidechain model to the project’s new Powpeg solution. RSK is a merge mined Ethereum-like Bitcoin sidechain developed by IOVlabs. Bitcoin users can effectively move their coins to this blockchain that operates more like Ethereum, and move the coins back to the Bitcoin blockchain when they so choose. Some Bitcoin miners utilize their hashpower to mine bocks on the sidechain, and earn some extra transaction fees by doing so.The tricky part of any sidechain is allowing users to securely move their coins between blockchains. This is technically done by locking coins on the Bitcoin blockchain and issuing corresponding coins on the sidechain, and vice versa: locking coins on the sidechain to unlock the coins on the Bitcoin blockchain.So far, RSK did this by locking the coins into a multi-signature address, for which the private keys were controlled by a group of well-known companies. A majority of them was needed to unlock the coins, which they were to only do if and when the corresponding sidechain coins were locked.RSK is now switching to a Powpeg model where the keys to the multi-signature address are controlled by special tamper-proof hardware modules that are in turn programmed to only unlock coins on the Bitcoin blockchain if and when the corresponding coins on the sidechain are locked, and the transactions to lock these coins up have a significant number of confirmations.Aaron and Sjors explain how this works exactly, and discuss some of Powpeg’s security tradeoffs.

In this episode of The Van Wirdum Sjorsnado, hosts Aaron van Wirdum and Sjors Provoost discussed Bitcoin mempools, Child Pays For Parent (CPFP) and package relay.

Package relay is the project that Gloria Zhao will work on as part of her Brink fellowship, which was announced earlier this week, and would make the Lightning Network more robust (among other benefits). Mempools are the collections of unconfirmed transactions stored by nodes, from which they forward transactions to peers. Miners usually select the transactions from their mempools that include the highest fees, to include these in the blocks they mine.

Mempools can get full, however, at which point transactions that pay the lowest fees are ejected. This is actually a problem in context of CPFP, a trick that lets users speed up low-fee transactions by spending the coins from that transactions in a new transaction with a high fee to compensate. Tricks like these can be particularly important in the context of time-sensitive protocols like the Lightning Network.

In this episode, van Wirdum and Provoost explained how package relay could enable CPFP, even in cases where low-fee transactions are dropped from mempools, by bundling transactions into packets. And they explore why this may be easier said than done.

In this episode of The Van Wirdum Sjorsnado, Aaron and Sjors discuss the Erebus Attack. The episode is a follow-up from last week’s episode on Eclipse Attacks, a type of attack that isolates a Bitcoin node by occupying all of its connection slots to block the node from receiving any transactions. Erebus Attacks are Eclipse Attacks where an attacker essentially spoofs a whole part of the internet.

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Follow Bitcoin Magazine on Twitter @BitcoinMagazine
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Follow Sjors Provoost @provoost

Music:
Song Title: Segwit Sounds
By: The NakamoTones
Album: Citadel Music
Produced by: Bitcoin Audio

In this episode of The Van Wirdum Sjorsnado, Aaron and Sjors discuss Eclipse attacks. More specifically, they discuss the 2015 paper “Eclipse Attacks on Bitcoin’s Peer-to-Peer Network,” written by Ethan Heilman, Alison Kendler, Aviv Zohar and Sharon Goldberg, from Boston University and Hebrew University/MSR Israel.

Support the Show!
Follow Bitcoin Magazine on Twitter @BitcoinMagazine
Follow Aaron van Wirdum @AaronvanW
Follow Sjors Provoost @provoost

Music:
Song Title: Segwit Sounds
By: The NakamoTones
Album: Citadel Music
Produced by: Bitcoin Audio

In this episode of The Van Wirdum Sjorsnado, Aaron and Sjors discuss Open Timestamps, a Bitcoin-based time stamping project by applied cryptography consultant and former Bitcoin Core contributor Peter Todd. Open Timestamps leverages the security of the Bitcoin blockchain to timestamp any type of data, allowing for irrefutable proof that that data existed at a particular point in time.

Support the Show!
Follow Bitcoin Magazine on Twitter @BitcoinMagazine
Follow Aaron van Wirdum @AaronvanW
Follow Sjors Provoost @provoost

Music:
Song Title: Segwit Sounds
By: The NakamoTones
Album: Citadel Music
Produced by: Bitcoin Audio

Support the Show!
Follow Bitcoin Magazine on Twitter @BitcoinMagazine
Follow Aaron van Wirdum @AaronvanW
Follow Sjors Provoost @provoost

Music:
Song Title: Segwit Sounds
By: The NakamoTones
Album: Citadel Music
Produced by: Bitcoin Audio

Bitcoin Core 0.21 will support Tor v3 addresses. Aaron and Sjors explain what this means and why it matters, and also discuss how new Bitcoin nodes find existing Bitcoin nodes when they bootstrap to the network.

Helpful Links:

* Tor V3 (onion) address support in Bitcoin Core: https://github.com/bitcoin/bitcoin/pull/19954

* the ADDRv2 message added in BIP155 that allows nodes to gossip those new Tor addresses: https://github.com/bitcoin/bips/blob/master/bip-0155.mediawiki#Specification

* DNS seeds and the bootstrap problem: https://stackoverflow.com/questions/41673073/how-does-the-bitcoin-client-determine-the-first-ip-address-to-connect

Timestamps:

00:00 - 00:34 - intro 

1:02 - 2:10: how Tor Works

2:25 - 3:03: benefits of running a bitcoin node behind tor. 

7:12 - 8:19 Discussing how Bitcoin node gossip addresses. 

8:56 - 10:40 Explaining how DNS works 

12:30 - 13:30: DNS is storing list of bitcoin nodes. 

Support the Show!

Follow Bitcoin Magazine on Twitter @BitcoinMagazine

Follow Aaron van Wirdum @AaronvanW

Follow Sjors Provoost @provoost

Follow Ruben Somsen @SomsenRuben

Music:

Song Title: Segwit Sounds

By: The NakamoTones

Album: Citadel Music

Produced by: Bitcoin Audio