This file was created by the TYPO3 extension bib --- Timezone: CEST Creation date: 2024-04-19 Creation time: 09-05-22 --- Number of references 5 inproceedings 2017-maurer-trustcom-coinjoin 2017 8 1 522-529 https://www.comsys.rwth-aachen.de/fileadmin/papers/2017/2017-maurer-trustcom-coinjoin.pdf Online IEEE 2017 IEEE Trustcom/BigDataSE/ICESS Sydney, NSW, Australia 16th IEEE International Conference on Trust, Security and Privacy in Computing and Communications (IEEE TrustCom) 1. - 4. August 2017 978-1-5090-4906-6 2324-9013 10.1109/Trustcom/BigDataSE/ICESS.2017.280 1 Felix KonstantinMaurer TillNeudecker MartinFlorian mastersthesis felix_konstantin_maurer_master_thesis 2016 9 30 Bitcoin is a new cryptocurrency with several advantages over previous approaches. All transactions are validated, processed, and stored by a peer-to-peer network. This prevents double-spending and control by a single entity. Furthermore, no one can prevent you from spending your coins. Any user can generate an unlimited number of pseudonyms in the form of Bitcoin addresses and use them to send and receive coins. However, as all transactions are public, it is theoretically possible to link addresses. As soon as one pseudonym of a person is known his balance and past transactions can be partially discovered. Many solutions were already proposed to remedy the linkability of addresses. Mixing or tumbling services receive coins from users, shuffle them and send unlinked coins back. As an alternative, similar services implemented in a peer-to-peer network were developed. A well-known example are CoinJoin transactions, where multiple users build a Bitcoin transaction together. New, Bitcoin inspired cryptocurrencies called altcoins go even further. They provide additional functions and often also increased built-in anonymity but are not backwards compatible with Bitcoin. The compatible solutions usually require all users to mix the same amount. Otherwise, addresses could be linked through unique valued coins they send and receive. Therefore, these services have to be used in addition to normaltransactions. This thesis provides an extensive overview over existing works on the topic of anonymity in Bitcoin. We present methods to deanonymize users as well as approaches to render them ineffective and compare them. Then we investigate the problem of address linking by coin value. We develop a model that can be used to calculate the probability of addresses in a CoinJoin transaction being linked. Using a custom tool we generate CoinJoin transactions and analyze them using the model. Furthermore, we propose a simple method of modifying CoinJoin transactions. We are able to demonstrate that it successfully lowers the linkability of addresses. Finally we illustrate how our model can be extended and how our results can be used in future works. Karlsruhe Institute of Technology Institut für Telematik Master Thesis 1 Felix KonstantinMaurer article felix_konstantin_maurer_informatik_2016_bitcoin INFORMATIK 2016 2016 9 26 P-259 2145-2150 Bitcoin is a crypto currency with several advantages over previous approaches. Transactions are confirmed and stored by a peer-to-peer network in a blockchain. Therefore, all transactions are public and soon solutions where designed to increase privacy in Bitcoin Many come with downsides, like requiring a trusted third-party or requiring modifications to Bitcoin. In this paper, we compare these approaches according to several criteria. Based on our findings, CoinJoin emerges as the best approach for anonymizing Bitcoins today. Bonner Köllen Verlag GI-Edition - Lecture Notes in Informatics (LNI) 78-3-88579-653-4 1617-5468 1 Felix KonstantinMaurer article felix_konstantin_maurer_dfn_forum_fosp 7. DFN-Forum Kommunikationstechnologien 2014 6 17 P-231 57-66 Bonner Köllen Verlag GI-Edition - Lecture Notes in Informatics (LNI) 978-3-88579-625-1 1617-5468 1 Felix KonstantinMaurer SebastianLabitzke thesis felix_konstantin_maurer_bachelor_thesis 2013 11 29 The way the World Wide Web (WWW) is used has changed since it was developed about 20 years ago. It began as a system for publishing interlinked hypertext documents and evolved into a whole application platform. Even non-technical users can now upload new content. On several websites, they can interact with their friends and form online social networks. The languages and formats used to build those websites and the protocols to transfer them are open standards and ensure that users can access them on any device using their favorite operating system and browser. However, the published content is no longer a whole hypertext document but more granular pieces of information, like posts, comments and pictures. Today, the way it can be accessed is restricted by how it is delivered as part of a website. The websites themselves no longer are the content but they are platforms that are not open like the technologies they’re build on. In this thesis, we will first examine the problems that arise from this situation. Then we take a look at existing work, which tries to counter those problems. After defining the requirements on a solution, we present the Federated Object Sharing Protocol (FOSP). We describe how we implemented a proof-of-concept FOSP server and client and then evaluate them with regard to the requirements we identify earlier in this thesis. The evaluation includes a discussion of possible extensions and variations to FOSP. We conclude this thesis with an outlook on future work. Karlsruhe Institute of Technology Institut für Telematik Forschungsbereich Dezentrale Systeme und Netzdienste Bachelor Thesis 1 Felix KonstantinMaurer