- A Security Focused Outline on Bitcoin WalletsRoman BögliMar 2023
The famous electronic peer-to-peer cash system called Bitcoin is an open-source protocol allowing individuals to store and transact units of the same named currency. Private and public key cryptography plays a central role in this value transfer system, which implies the importance of professionally managing the information about such keys. This work elaborates on the essential prerequisites to understand this relatively new technology that combines elements from the fields of computer science, cryptography, mathematics, and game theory. In doing so, crucial general and Bitcoin-specific terms are defined and contextually explained. The central part of this work addresses the outline of different Bitcoin interaction means, commonly known as wallets. The structure of the presented wallet types orients itself alongside a potential user’s experience. Besides defining explanations and examples of use cases, this work outlines advantages and disadvantages concerning security and privacy. The start concerns two wallets that target beginners in the field of Bitcoin. The concept of online accounts is elaborated and attention is drawn to the inherent need to trust when using them. Also, the relatively primitive type of paper wallets is surveyed. For a more intermediate interaction with this peer-to-peer cash system, the concept of software wallets, in general, is explained and examples are provided. The bridge from single-address paper wallets will be drawn to the more sophisticated multi-address wallets enabled through rooted key derivation techniques. Designated computer devices that solely serve the purpose of managing keying material, known as hardware wallets, represent another intermediate wallet type discussed in this work. Last, advanced topics are discussed that further leverage the security and privacy of someone’s interaction with Bitcoin. One concerns the setup of a self-managed Bitcoin full node. This undertaking not only harmonies with the concept of verification over trust but also allows for the complete exclusion of any third party between wallet communication. Equally advanced is the concept of multi-signature wallets, which is discussed at the end of this work.
- Zero-Knowledge Inclusion ProofsRoman BögliAug 2023
This work discusses a solution for implementing a zero-knowledge inclusion proof using existing software components, referred to as automation frameworks. In the beginning, the use case that necessitates such proofs is stated together with establishing the contextual backdrop. This includes elaborating essential prerequisites such as cryptographic hash functions, commitment schemes, and Merkle trees. Furthermore, it presents an overview of zero-knowledge proof systems, detailing their core characteristics, analogies, and real-world applications. The discussion delves into the two prominent implementation families, namely zkSNARK and zkSTARK, emphasizing their distinguishing features. To ensure resistance against potential threats originating from quantum computers, the proposed approach centers on utilizing non-interactively employed zkSTARK proofs enabled through the Fiat-Shamir transformation. Finally, this work formally states the objective of the zero-knowledge inclusion proof for the specific use case and proposes an algorithmic specification. A curated selection of promising automation frameworks with the potential to facilitate the objective’s implementation is presented, with in-depth scrutiny applied to two specific frameworks: RISC Zero and the Winterfell. The work concludes by discussing initial experiences with these frameworks and outlining future endeavors to chart the path towards implementing a minimal viable product. The appendix complements the discussion by providing an overview of current post-quantum cryptography developments.
- Time Series Clustering with Water Temperature DataRoman BögliAug 2020
This thesis studies three different approaches to cluster long-term water temperature data using the unsupervised pattern recognition method called hierarchical clustering. The cluster qualities are assessed using internal cluster validity indexes and forecast deviation analysis.
- Statistical vs. Structural Pattern Recognition - A SurveyRoman BögliDec 2019
This paper surveys the different approaches in pattern recog- nition (PR). After the fundamental idea of PR is stated, a taxonomy landscape is presented which divides into three families, namely statisti- cal, structural, and hybrids. The first represents a well-researched topic in PR which engendered popular and efficient supervised and unsupervised pattern discovery algorithms. The second family addresses techniques to find patterns in structurally represented data using graphs that allow capturing the information of relationships among objects. Thirdly, the hybridization of the prior two families will be discussed. This includes the elaboration of transformation methods that allow to embed a graph into a vector space using graph kernels or graph embedding.