schmidty

bitcoin

Mark “Murch” Erhardt and Mike Schmidt are joined by Gustavo Flores Echaiz to discuss Newsletter #374:

- The script restoration BIPs
- A BDK Wallet release and release candidates from Bitcoin Core and LND
- Our weekly notable code segment

You can listen on our website:
https://bitcoinops.org/en/podcast/2025/10/07/ 

Fountain:
https://fountain.fm/episode/bN5DD679k2z2NLqaNvHQ 

Spotify:
https://open.spotify.com/episode/2Fpd2NSKSAFydTy02y9cUv

Apple Podcasts:
https://podcasts.apple.com/us/podcast/bitcoin-optech-newsletter-374-recap/id1674626983?i=1000730656614

Bitcoin Optech Newsletter #374 Recap Podcast

Some thoughts on Bitcoin Core developer funding

That this was a public venue I thought good to highlight that independence for onlookers as well.

Bitcoin Optech newsletter #374 is here:

- links to the draft BIPs for Script Restoration
- Bitcoin Core 30.0rc2
- Optech Newsletter #374 Podcast
https://bitcoinops.org/en/newsletters/2025/10/03/

Rusty Russell posted to the Bitcoin-Dev mailing list a summary and four BIPs in various stages of draft relating to a proposal to restore Script’s capabilities in a new tapscript version...
https://bitcoinops.org/en/newsletters/2025/10/03/#draft-bips-for-script-restoration

Bitcoin Optech will host an audio recap discussion of this newsletter on Riverside.fm Tuesday at 16:30 UTC. Join us to discuss or ask questions!
https://riverside.fm/studio/bitcoin-optech

Bitcoin Optech Newsletter #374

Matt Morehouse, Daniela Brozzoni, and Gustavo Flores Echaiz joined Optech to discuss Newsletter #373:

- Eclair vulnerability
- Research into feerate settings
- 12 Bitcoin Stack Exchange questions with an OP_RETURN focus
- Bitcoin Core 30.1 release candidate and testing guide
- And more

You can listen on our website: https://bitcoinops.org/en/podcast/2025/09/30/

Fountain: https://fountain.fm/episode/HUKeJE4y8iPGSD9WL4VS

Spotify: https://open.spotify.com/episode/55tV1tepMDPFtcONy8kHQI

Apple Podcasts: https://podcasts.apple.com/us/podcast/bitcoin-optech-newsletter-373-recap/id1674626983?i=1000729551630

Bitcoin Optech Newsletter #373 Recap Podcast

I posted this on X/Twitter the other day and perhaps folks here would be interested in the perspective. The posts tags many individuals and organizations (so much so that Twitter made me split it into 2 tweets) so its harder to reproduce here. 

https://x.com/bitschmidty/status/1971612924180369799
https://x.com/bitschmidty/status/1971612926462329199

Dont believe the catastrophizing - a perspective on Bitcoin development

Hey @theariard Im not sure what you mean. This was just me being overly-communicative on the independence of the engineers we sponsor at Brink.

Fuzz testing and Bitcoin Core...

We received a pretty overwhelming response to our recent job post for a Bitcoin Core Fuzzing Internship at Brink.

Brink received over 70 applications for the role with many qualified candidates.

After the results of a coding challenge, we decided to actually move forward with two engineers for the 3 month role.

Dongjia Zhang is a Ph.D. fuzzing researcher and maintainer of the LibAFL fuzzing library used to fuzz test Bitcoin Core.

Stratos has a background in vulnerability research and will join Dongjia in working with Niklas in the coming months to enhance the fuzz testing capabilities in Bitcoin Core.

Fuzz testing is the idea of throwing a bunch of quasi-random inputs at various functions of a codebase and seeing if anything abnormal happens. Think of it like mining for bugs.

There is work in both the Bitcoin Core codebase as well as fuzz tooling (like fuzzamoto) in order to test more and more of Bitcoin Core in this way.

Here is a bit more about fuzz testing in Bitcoin Core: https://brink.dev/blog/2023/07/14/fuzzing/

Here is a conversation we had with Matt Morehouse on fuzz testing the Lightning Network:
https://brink.dev/blog/2024/06/25/eng-call-fuzz-testing-lightning/

Marco recently completed his year long onsite fuzzing fellowship at Brink and provided some thoughts as well: https://brink.dev/blog/2025/07/31/marco-fuzzing-fellowship/

Brink is proud to support the build out of further fuzzing capabilities in the Bitcoin Core codebase as well as other ecosystem softwares. We have not had intern roles before either and are excited to see how it works out.

Welcome Dongjia and Stratos!
https://brink.dev/programs#brink_interns 

Brink announces funding for two fuzz testing interns for Bitcoin Core

Bitcoin Optech Newsletter #373 is here:

- summarizes a vulnerability affecting old versions of Eclair
- summarizes research into full node feerate settings
- summarizes popular Q&A from Stack Exchange
- Optech Newsletter #373 Podcast
https://bitcoinops.org/en/newsletters/2025/09/26/

Matt Morehouse posted to Delving Bitcoin to announce the responsible disclosure of a vulnerability affecting older versions of Eclair...
https://bitcoinops.org/en/newsletters/2025/09/26/#eclair-vulnerability

Daniela Brozzoni posted to Delving Bitcoin the results of a scan of almost 30,000 full nodes that were accepting incoming connections...
https://bitcoinops.org/en/newsletters/2025/09/26/#research-into-feerate-settings

Selected Q&A from Bitcoin Stack Exchange:
- Implications of OP_RETURN changes in upcoming Bitcoin Core version 30.0?
- If OP_RETURN relay limits are ineffective, why remove the safeguard instead of keeping it as a default discouragement?
- What are the worst-case stress scenarios from uncapped OP_RETURNs in Bitcoin Core v30?
- If OP_RETURN needed more room, why was the 80-byte cap removed instead of being raised to 160?
- If arbitrary data is inevitable, does removing OP_RETURN limits shift demand toward more harmful storage methods (like UTXO-inflating addresses)?
- If OP_RETURN uncapping doesn’t increase the UTXO set, how does it still contribute to blockchain bloat and centralization pressure?
- How does uncapping OP_RETURN impact long-term fee-market quality and security budget?
- Assurance blockchain will not suffer from illegal content with 100KB OP_RETURN?
- What analysis shows OP_RETURN uncapping won’t harm block propagation or orphan risk? 
- Where does Bitcoin Core keep the XOR obfuscation keys for both block data files and level DB indexes?
- How robust is 1p1c transaction relay in bitcoin core 28.0?
- How can I allow getblocktemplate to include sub 1 sat/vbyte transactions?
https://bitcoinops.org/en/newsletters/2025/09/26/#selected-qa-from-bitcoin-stack-exchange

Bitcoin Optech will host an audio recap discussion of this newsletter on Riverside.fm Tuesday at 16:30 UTC. Join us to discuss or ask questions!
https://riverside.fm/studio/bitcoin-optech

Bitcoin Optech Newsletter #373

Jan B has put together a guide for testing the updates in the forthcoming Bitcoin Core v30.0 release.

Testing a few components in your setup and providing feedback is valuable!



Bitcoin Core 30.0 Release Candidate Testing Guide

The topic of non-developer contributions to Bitcoin and Bitcoin Core came up in a thread the other day. So I wanted to elevate this list, in case people are interested.

Ways to contribute other than code:

**Education / Outreach**
Optech
Conferences
Saving Satoshi
Fundraising
Bitdevs

**User feedback**
Reproducing issues
Priorities?

**Security**
Dependency auditing
CVE disclosure
Mailing list
Pen testing

**Dev Tooling**
CI
Signet
Fuzzing
Drahtbot
Corecheck,dev
Bitcoin dev wiki

**Mentoring**
Developer hubs
Review clubs

**Release Process**
Testing guide
Building binaries
Signing binaries
translations
Packaging for distro

**Monitoring**
b10c stuff etc

**Standardization**
BIPs
Bolts etc

**Events**
Coredev
Online communication channels
Mailing list
Delving
IRC
Twitter / etc
Stack exchange
http://bitcoincore.org
Backups of stuff

**Dev Infrastructure**
Fuzzing
Devops stuff
Dns seeds

**User feedback**
Outward
Talk to miners? Exchanges? Surveys

**Research**
BRW

Janitor work
Reproducing

**Other items listed:**
Coredev
conference
BIPs (review, reading)
Stack exchange
CI
Fuzzer machines
Devops
Monitoring
http://bitcoincore.org maintaining/hosting
Signet / inquisition
Utilities for interacting with Bitcoin (Core)
Educational stuff like saving satoshi
Delving
Mailing list
Backup of delving/mailing list/github comments
IRC and logs
Drahtbot / meetingbot
Bitcoinacks (?)
Fundraising
Developer hubs
Review clubs
Technical talks / podcasts / outreach
Bitdevs
Deterministic builds (running)
Dns seed
Dependency auditing/pruning
Architecture CI doesn’t account for
Reproducing issues
Moderation of github
Research Week
Twitter threads
Translations
Security
Security mailing list
CVE management / disclosure etc
Pen testing
http://Corecheck.dev
Core dev wiki
Bitcoin wiki
Summaries of communal knowledge
Optech
Release packaging for distros
Janitoring old issues/PRs
BOSS program
Summer of Bitcoin

Original:
https://btctranscripts.com/bitcoin-core-dev-tech/2025-02/non-development-contributions

How to contribute to Bitcoin or Bitcoin Core other than code

ZmnSCPxj and Constantine Doumanidis joined Optech to discuss Newsletter #372:

- LSP-funded redundant overpayments
- Partitioning and eclipse attacks using BGP interception 
- Changes to services and client software
- Bitcoin Core 30.0rc1 
- And more

You can listen on our website: https://bitcoinops.org/en/podcast/2025/09/23/

Fountain: https://fountain.fm/episode/roAtQyqbkVOkZxNBz4z0

Spotify: https://open.spotify.com/episode/6lQx7XYXHK6o4u6iEjt1x6

Apple Podcasts: https://podcasts.apple.com/us/podcast/bitcoin-optech-newsletter-372-recap/id1674626983?i=1000728103838

Bitcoin Optech Newsletter #372 Recap Podcast

This is content from my response to Adam Back on twitter, reformatted for Stacker News

Ref: https://x.com/bitschmidty/status/1970485709069852729

Happy to answer any questions

---

Id estimate Bitcoin Core developer funding is similar to what 1A1z outlined in last years report (https://s3.amazonaws.com/1a1z.com/files/1A1z%20-%20Funding%20Bitcoin%20-%20Part%201.pdf)

Since then, 2140 and localhost research have come online which is good for decentralization.

There are good new Bitcoin Core developer candidates coming out of Chaincode's BOSS program who I think are worthy of funding.

At Brink we just had Marco finish his year long fuzz testing fellowship in London and he has moved to full time (https://brink.dev/blog/2025/07/31/marco-fuzzing-fellowship/) and will be announcing 2 fuzz testing interns shortly.

> i'd suspect there are too many contributors

I don't think the situation is dire by any means, but 30-40 full time engineers focusing on maintaining and hardening mission critical software for a $2.5T network doesnt feel like too many to me.

> funding has overshot

See above. But also, grants/salaries are still quite below industry salaries, although better than years past. Additional monies can provide funding organizations runway which helps attract new engineers. New orgs are good for decentralization and also need funding. We also want to make sure new contributors get involved (think: bus factor, turnover, etc). There are initiatives that dont involve engineer salaries as well (compute power, software/services, etc)

If anything the room for improvement is more diverse funding sources (good for decentralization and perception of "influence" issues) and donations/pledges that are longer term (low time preference).

> funding for a purpose

Funding for specific deliverables is hard in open source and probably harder in Bitcoin and even harder in Bitcoin Core. That said, I do think many funding orgs do have focus areas. Brink for example is security, testing, review, and maintenance work. Others have focus areas as well. Donors can choose what kinds of initiatives/purposes they want to support.

The importance of minimizing dependencies in Bitcoin Core

I think the OpenSSL -> libsecp256k1 effort is a great example. Hard to articulate how much work it was to make libsecp256k1. The recent natpmp feature rewrite is another example, even if not as intense.

(also posted on X/twitter: https://x.com/bitschmidty/status/1969047197053575431)

Many people, myself included, tout the importance of software maintenance in the context of Bitcoin Core. It is easy to throw out "maintenance!" and most people will nod their head in agreement, but I think its helpful to have some examples to understand the depth of this work and risks of not doing it.

There are many categories of maintenance work, today I am just going to zoom in on one: minimizing dependencies.

Recently someone attempted to put in a backdoor into XZ, a library used by softwares in hundreds of millions of computers around the world. Even a couple weeks ago hackers slipped malicious code into dozens of NPM packages that receive millions of downloads each week.

Bitcoin Core and other Bitcoin software are not immune to these kinds of attacks. While Bitcoin Core has a robust culture of code review and testing, Bitcoin Core uses third-party libraries as well. Code from these libraries is run, in addition to Bitcoin Core's code, when you are running your node.

Any bug, vulnerability, or performance issue in these libraries (dependencies) can cause issues for Bitcoin Core. Updates to these dependencies of Bitcoin Core are a potential risk and need to be regularly tracked and reviewed. From a security perspective, these dependencies should also be minimized and eliminated where possible.

Bitcoin Core developers have spent years minimizing the number of dependencies of the project. In some cases replacing them with minimal, in-house alternatives that achieve the same function in order to reduce attack surface.

In this latest Brink blog, we outline the risks of using dependencies as well as several examples of Bitcoin Core removing problematic or unnecessary dependencies of the project.


Bitcoin Optech Newsletter #372 is here:

- summarizes a proposal to enhance LN redundant overpayments
- links to a discussion about potential partitioning attacks against full nodes
- summarizes changes to services/client software
- Optech Newsletter #372 Podcast
https://bitcoinops.org/en/newsletters/2025/09/19/

ZmnSCPxj posted to Delving Bitcoin a proposal to allow LSPs to provide the additional funding (liquidity) required for redundant overpayments...
https://bitcoinops.org/en/newsletters/2025/09/19/#lsp-funded-redundant-overpayments

Developer cedarctic posted to Delving Bitcoin about using flaws in the Border Gateway Protocol (BGP) to prevent full nodes from being able to connect to peers...
https://bitcoinops.org/en/newsletters/2025/09/19/#partitioning-and-eclipse-attacks-using-bgp-interception

Changes to services and client software:
- Zero-knowledge proof of reserve tool
- Alternative submarine swap protocol proof of concept
https://bitcoinops.org/en/newsletters/2025/09/19/#changes-to-services-and-client-software

Bitcoin Optech will host an audio recap discussion of this newsletter on Riverside.fm Tuesday at 16:30 UTC. Join us to discuss or ask questions!
https://riverside.fm/studio/bitcoin-optech

Bitcoin Optech Newsletter #372

Jonas Nick and Bastien Teinturier joined Optech to discuss Newsletter #371:

- a workbook for learning cryptography
- the eclair 0.13 release
- the release candidate for bitcoin core 30.0
- and more

You can listen on our website: https://bitcoinops.org/en/podcast/2025/09/16/  

Fountain: https://fountain.fm/episode/FDSWN4dSOtzy7kezMw3G 

Spotify: https://open.spotify.com/episode/240Htez9aCxIINL1rqCuWy 

Apple Podcasts: https://podcasts.apple.com/us/podcast/bitcoin-optech-newsletter-371-recap/id1674626983?i=1000727098773

Bitcoin Optech Newsletter #371 Recap Podcast

Schmidty: Some notes about in person Bitcoin Core developer meetings, Brink

Scoresby

Bitcoin Optech newsletter #371 is here:

- announces the availability of a workbook dedicated to provable cryptography
- Bitcoin Core 29.1, Eclair v0.13.0, Bitcoin Core 30.0rc1
- Optech Newsletter #371 Podcast

https://bitcoinops.org/en/newsletters/2025/09/12/

Jonas Nick posted to Delving Bitcoin to announce a short workbook he created for a four day event to “teach developers the basics of provable cryptography, […] consisting of cryptographic definitions, propositions, proofs and exercises.”
https://bitcoinops.org/en/newsletters/2025/09/12/#provable-cryptography-workbook

Bitcoin Optech will host an audio recap discussion of this newsletter on Riverside.fm Tuesday at 16:30 UTC. Join us to discuss or ask questions!
https://riverside.fm/studio/bitcoin-optech

Bitcoin Optech Newsletter #371

Russell O’Connor, Olaoluwa Osuntokun, and Jeremy Rubin join Optech to discuss Newsletter #370:

- Simplicity
- 4 proposed op codes for doing Elliptic Curve Operations in Bitcoin Script
- Draft BIP for OP_TWEAKADD
- and more

You can listen on our website: https://bitcoinops.org/en/podcast/2025/09/09/

Fountain: https://fountain.fm/episode/6IP69xVggsPJ4dZtShuf 

Spotify: https://open.spotify.com/episode/1InhHmSFSrggcAxafzymWS

Apple Podcasts: https://podcasts.apple.com/us/podcast/bitcoin-optech-newsletter-370-recap/id1674626983?i=1000725872238

Bitcoin Optech Newsletter #370 Recap Podcast

@schmidty's bio

I suppose this doesnt help either, but here it is anyway

https://github.com/bitcoinops/bitcoinops.github.io/pull/608/commits/c185556fa1a922d860e4d7f99feb7b8f38ea5f7d

Ill try to remember to drop something in the next pod tomorrow