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The UTXO model A technical cornerstone of Bitcoin Visualization of a transaction. Image by Satoshi Nakamoto (Bitcoin: A Peer-to-Peer Electronic Cash System) Bitcoin is based on the UTXO (unspent transaction output) model to ensure that nobody is able to spend money they don’t have and prevent money from being spent twice — so-called double-spending. In this article, you … Read More »

Docker Security 😇 A hands-on guide to security for Docker Photo by Andrey Sharpilo on Unsplash Most companies I have seen deploy Docker images in at least one project or service. Docker is great because it makes stuff reproducible by specifying the environment to a big degree. However, you still have to think about security. Let’s have a closer … Read More »

Encryption vs Encoding vs Hashing They might appear in the same context, but they are vastly different Encryption is about keeping a secret and being able to restore it. Hashing is about fingerprinting — you don’t need to restore the original, but you need to make sure it is identical. Encoding is about data representation to enable information exchange. Encoding does not involve keeping secrets. This was … Read More »

Insecure Deserialization 😈🐝 Serialization is the act of transforming objects from an internal representation to a stream of characters or bytes. The representation of the serialized object should be platform- and language-independent. Data is serialized and deserialized in applications to store or transport it. In web applications, JSON or XML is often used … Read More »

Merkle Trees The concept and applications - plain and simple! A Merkle Tree is a binary tree with the data at the leaf nodes. All inner nodes are hashes. A Merkle Tree is a data structure that is used in Peer-to-Peer Networks. It is a binary tree in which the value of an inner node is the hash of its … Read More »

The 3 Applications of Hash Functions What they are, what the options are, and why they matter Image by Martin Thoma Hash functions take arbitrary many bytes as input and produce a fixed-length string as output. The string typically looks completely random, but the same input always generates the same output. They also typically produce different outputs for different inputs, but more about that later. After reading … Read More »

HTTPS vs SSL vs TLS What they are and what the differences are Image by Martin Thoma HTTPS, SSL, and TLS are all related to encrypted (“secure”) internet connections. The problem they solve is that a man in the middle could read the data you receive or send. It is clearly an issue when you log in to your bank or when you … Read More »

The Blockchain An Introduction to Blockchain, Bitcoin ₿, and related concepts An example of a blockchain. Image by Martin Thoma. Bitcoin crossed $40,000 USD for the first time recently, so it’s again in the news. Bitcoin is just the most-known cryptocurrency. It is one application using a blockchain. In this article, I will walk you through some core concepts … Read More »

6 YAML Features most programmers don’t know Level-up your YAML knowledge to write cleaner YAML files YAML is a file format commonly used for data serialization. There are a plethora of projects using YAML files for configuration, such as Docker-compose, pre-commit, TravisCI, AWS Cloudformation, ESLint, Kubernetes, Ansible, and many more. Knowing the features of YAML helps you with all of them. Let’s cover the basics … Read More »

365 Main Dishes This is an article I had for quite a while as a draft. As part of my yearly cleanup, I've published it without finishing it. It might not be finished or have other problems. I don't want to spend a lot of thought into what I'm going to eat. I'm … Read More »