Welcome to the BTC204 course!

In a world where the confidentiality of financial transactions is gradually becoming a luxury, understanding and mastering the principles of privacy protection when using Bitcoin is essential. This course gives you all the keys, both theoretical and practical, to achieve this autonomously.

Today, many companies specialize in blockchain analysis for Bitcoin. Their core business consists precisely of intruding into your private sphere to compromise the confidentiality of your transactions. In reality, there is no such thing as a "right to privacy" in Bitcoin. Therefore, it's up to you, the user, to assert your natural rights and protect the confidentiality of your transactions, as no one else will do it for you.

Bitcoin isn't just about "Number Go Up" and preserving the value of savings. With its unique characteristics and history, it is, first and foremost, a tool of the counter-economy. Thanks to this formidable invention, you can freely dispose of your money, spend it, and accumulate it, without anyone being able to stop you.

Bitcoin offers a peaceful escape from the state's yoke, allowing you to fully enjoy your natural rights, which cannot be challenged by established laws. Thanks to Satoshi Nakamoto's invention, you have the power to enforce respect for your private property and regain the freedom to enter into contracts.

However, Bitcoin is not anonymous by default, which can pose a risk for individuals involved in the counter-economy, particularly in regions under authoritarian rule. But this is not the only danger. Since bitcoin is a valuable and uncensorable asset, it can be a target for thieves. Therefore, protecting your privacy becomes a matter of security as well, as it can help prevent hacking and physical assault.

As we'll see, although the protocol offers certain confidentiality protections in its own right, it's crucial to use additional tools to optimize and defend this confidentiality.

This course offers a comprehensive overview of the issues surrounding Bitcoin confidentiality. Each technical concept is covered in detail, supported by explanatory diagrams. The aim is to make this knowledge accessible to everyone, even beginners and intermediate users. For more seasoned Bitcoiners, we also cover highly technical and sometimes lesser-known concepts throughout the course to deepen their understanding of each subject.

The aim of this course is not to render you completely anonymous in your use of Bitcoin, but rather to equip you with the essential tools to protect your confidentiality according to your personal objectives. You'll have the freedom to choose from the concepts and tools presented to develop your own strategies, tailored to your specific goals and needs.

To begin with, we will review the fundamental principles governing Bitcoin's operation, so that we can then calmly address the notions related to confidentiality. It's essential to master a few basic concepts, such as UTXO, receiving addresses, and scripting, before you can fully understand the concepts we'll cover in the following sections. We will also introduce Bitcoin's general confidentiality model, as imagined by Satoshi Nakamoto, which will enable us to grasp the associated stakes and risks.

In the second section, we examine the techniques employed by blockchain analysis companies to track your activity on Bitcoin. Understanding these methods is crucial to strengthening your privacy protection. The aim of this section is to examine attackers' strategies in order to better understand the risks and prepare the ground for the techniques studied in the following sections. We will analyze transaction patterns, internal and external heuristics, and likely interpretations of these patterns. In addition to theory, we'll learn how to use a block explorer for chain analysis through practical examples and exercises.

In the third section of our course, we get down to the nitty-gritty: practice! The aim is to master all the essential best practices that should become natural reflexes for any Bitcoin user. We'll cover the use of blank addresses, tagging, consolidation, full node usage, as well as KYC and acquisition methods. The aim is to provide you with a comprehensive overview of the pitfalls to avoid in establishing a solid foundation for protecting privacy. For some of these practices, you will be guided to a specific tutorial on how to implement them.

How can we talk about privacy on Bitcoin without mentioning coinjoins? In section 4, you'll find out all you need to know about this mixing method. You'll learn what coinjoins are, their history and objectives, as well as the different types of coinjoins that exist. Finally, for the more experienced user, we'll take a look at what anonsets and entropy are, and how to calculate them.

In the fifth section, we'll take a look at all the other techniques available to protect your privacy on Bitcoin, apart from coinjoin. Over the years, developers have shown remarkable creativity in designing tools dedicated to privacy. We'll examine various methods, including PayJoin, collaborative transactions, Coin Swap, and Atomic Swap, detailing how they work, their objectives, and any potential weaknesses.

We'll also look at privacy at the level of the network of nodes and transaction propagation. We'll also discuss the various protocols that have been proposed over the years to enhance user privacy on Bitcoin, including static address protocols.

Ready to explore the intricacies of privacy on Bitcoin? Let's go!