0xB10C's Blog: Bitcoin Developer

I’m 0xB10C

I work fulltime on open-source Bitcoin projects and are currently supported by a Brink.dev Bitcoin Developer Grant. In 2021, Coinbase supported me with a Coinbase Bitcoin Developer Grant. I run mempool.observer, the Bitcoin Transaction Monitor, transactionfee.info, the miningpool.observer, an open-content and educational blog called bitcoin-dev.blog, and have worked on a lot of other projects over the past years.

I use the GPG key with the fingerprint 982A 193E 3CE0 EED5 35E0 9023 188C BB26 4841 6AD5 and without spacing 982A193E3CE0EED535E09023188CBB2648416AD5. The public key can be found here and on the ususal key servers. There is also a key transition notice (February 2021) for a key I previously used. I’m currently only avaliable for short-term Bitcoin freelance and consulting projects. My main focus lies on open-source projects.

Recent articles

November 16, 2022

Inbound Connection Flooder Down

Over the past few months, I’ve repeatedly observed very short-lived P2P connections with fake user agents being made to my Bitcoin Core node in a high succession. This morning around 7:00 am UTC, these abruptly stopped.

September 18, 2022

Are you a real Bitcoiner?

It’s well known that you are only a real Bitcoiner if you are a carnivore, eat red meat at least three times a week but never consume seed oils, lift heavy weights, are straight, white, unvaccinated, believe in the Christian god, got into Bitcoin before 2015, are a maximalist, stack sats …

August 24, 2022

P2TR spending transactions missing from F2Pool and AntPool blocks (2021)

My miningpool-observer project aims to detect when mining pools don’t mine transactions they could have mined. Right after taproot activation, it caught that F2Pool and AntPool didn’t mine P2TR (Pay-to-Taproot) spending transactions. This post is a write-up of this observation.

January 17, 2022

Extracting the Private Key from Schnorr Signatures that reuse a Nonce

Elliott (aka @robot__dreams) posted a Bitcoin-flavored cryptography challenge on Twitter. The goal is to extract the private key from two Schnorr signatures that reuse a nonce. I’ve recently reviewed and merged Kalle Rosenbaum’s cross-post of his Schnorr Basics post to bitcoin-dev.blog. …

August 30, 2021

Userspace, Statically Defined Tracing support for Bitcoin Core

This report updates on what 0xB10C, Coinbase Crypto Community Fund grant recipient, has been working on over the first half of his year-long Bitcoin development grant. This specifically covers his work on Userspace, Statically Defined Tracing support for Bitcoin Core. This report was published on …

July 23, 2021

On anyone-can-spend Pay-to-Taproot outputs before activation

While working on taproot support for transactionfee.info, it became apparent that there already exist a few Pay-to-Taproot (P2TR) outputs on mainnet. Anyone can spend these outputs, but they are non-standard and thus not relayed between nodes in the Bitcoin peer-to-peer network. However, a mining …

November 10, 2020

Evolution of the signature size in Bitcoin

Digital signatures are an essential building block of the Bitcoin protocol and account for a large part of the data stored on the blockchain. We detail how the size of the encoded ECDSA signatures reduced multiple times over the last years and how the proposed Schnorr signature compares to the …

July 13, 2020

Following the Blockchain.com feerate recommendations

Transactions sent with Blockchain.com wallets make up for about a third of all Bitcoin transactions. A methodology to identify these transactions is described and used. Insights about the wallet-usage are derived from the resulting dataset. The privacy implications and possible improvements are …

May 4, 2020

The daily BitMEX broadcast at 13:08 UTC

At around 13:00 UTC every day, BitMEX, a cryptocurrency exchange and derivative trading platform, broadcasts multiple megabytes of large transactions into the Bitcoin network. This affects the transaction fees paid during European afternoons and US business hours. The transaction size could be …

April 27, 2020

The stair-pattern in time-locked Bitcoin transactions

Some of the regularly used Bitcoin wallets, for example, the Bitcoin Core wallet and the Electrum Bitcoin Wallet, set the locktime of newly constructed transactions to the current block height. This is as an anti-fee-sniping measure and visible as a stair-like pattern when plotting time-locked …

October 10, 2019

Frequently Asked Questions: Bitcoin Transaction Monitor

The Bitcoin Transaction Monitor provides deeper insights into the usage of the Bitcoin network by showing transactions by time and feerate. This post answers frequently asked questions about the Bitcoin Transaction Monitor itself.

August 4, 2019

The Incomplete History of Bitcoin Development

To fully understand the rationale behind the current state of Bitcoin development, knowledge about historical events is essential. This blog post highlights selected historical events, software releases and bug fixes before and after Satoshi left the project. It additionally contains a section about …

June 29, 2019

A List of Public Bitcoin Feerate Estimation APIs

My search for a list of public Bitcoin feerate estimation APIs ended without any real results. Jameson Lopp has a section on feerate estimators on his bitcoin.page and Antoine Le Calvez’s dashboard txstats.com provides a visualization of different estimation APIs. But that is not what I was …

March 18, 2018

Plotting the Bitcoin Feerate Distribution

How did the median Bitcoin feerate evolve from 2013 to 2015? When were the feerate spikes in 2017? Visualizing the Bitcoin feerate distribution per block was on my todo list since I’ve started working on the first version of my mempool.observer project in mid-2017. But acquiring the data …

December 18, 2017

The 300 MB default maxmempool Problem

Unconfirmed transactions are quite a hassle for bitcoin users. I recently came across an interesting problem which is not the usual “my transaction is stuck” problem.