Hi, my name is Sebastian,

I am currently studying computer science at TU Dresden with a special focus on cryptography and distributed systems. If you want to learn more about me, click here or have a look at my projects.

Below you can find some of my most recent blog posts.

Accounting for Lightning's fees

Lightning is getting easier to use every day, leading to a lot of exciting services being built on top of it as they should be. But while better documentation and API bindings make it easy to use for even inexperienced developers there are still a few rough edges to be aware of or else one may become the target of attackers. One of these will be the topic of this article: fee handling for custodial lightning accounts.

Even though I agree on a philosophical basis that this shouldn't be an article I have to write because people are supposed not to trust custodial solutions, this is not the reality we live in. For a variety of reasons including UX, maintenance effort and available know how custodial solutions integrating lightning are often preferable, especially for small amounts of money.

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Bitcoin needs latency independent second layers

Many Arguments can be made in favor of second layers to bitcoin. The most common ones are efficiency, privacy and speed. For a long time I too thought these were the most important reasons. But during a recent twitter conversation with some BSV shills rehashing fork dynamics something else occurred to me: to successfully defend against a majority of miners trying to strong arm the community into accepting new rules we need to be able to carry on without the ability to transact on chain (or at least for much higher prices) for a period of time.

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Liquid Asset Directory

Screenshot of the list of assets o the asset directory page

Liquid is a federated sidechain to bitcoin developed by Blockstream and run by a federation of exchanges and other big Bitcoin industry players. Amongst its many features it supports asset issuance. When you look at liquid transactions you can see inputs with an issuance field from time to time, but till now it was really hard to find these transactions since neither blockstream.info nor liquid.horse list issued assets. That's why I built a Liquid Asset Directory that lists all issuances and reissuances. It also gives you the raw, JSON encoded data in case you want to run your own analysis.

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Lightning Shell: instant disposable root shells

I recently released Lightning Shell, a service to book access to a docker container with root access using Bitcoin's Lightning Network. It's meant for people who want to try out possibly untrusted software without polluting their system. In a future iteration I could also imagine self hosting Apps that book containers over an API, but that's still far from becoming reality.

One important goal was is usability without JavaScript. For that reason the payment processing uses iframes and http-equiv refresh to check for paid invoices and the containers can be accessed not only using a web tty but also via SSH.

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Building a Lightning candy dispenser

The candy dispenser in action

Back in September I attended the 3rd Lightning Network Hackday in Berlin organized by fulmo. It was a rather loose gathering of people working on all sorts of Bitcoin and Lightning related projects. One of the most fun applications of Lightning I saw there was a little electronic candy dispenser. The concept was simple but yet fascinating: a Raspberry Pi, embedded in the candy dispenser, ran lnd and served a website with an invoice displayed as QR code. Every time one sent money some M&Ms dropped out of the machine and a new invoice was generated. This turned out to be so much fun that I decided to build one myself.

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Rewriting my website

For a long time my website has been nothing more than a plain old HTML page with my e-mail address and GPG key.

My old website in firefox

But at times I had the desire to publish random thoughts, ideas and encounters, but I didn't want to use any of the centralized social networks. That's why I chose to rebuild my website as a blog using a static site generator named Gutenberg (RIIR, yay!). For now the whole setup is quite hacky since I patched in some features I needed but didn't get around to propose them upstream till now.

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