École Nationale Supérieure de
Techniques Avancées

Abstract

The blockchain technology spearheaded by Bitcoin has been the talk of the town in recent years. Indeed, this technology promises numerous applications that are expected to revolutionize the way we conceive money or the authentication of documents without the need for intermediaries. The blockchain can be seen as a decen- tralized database based on a peer-to-peer network. However, this system, like any other information system, is subject to attacks from malicious individuals. The first step will therefore be to understand in depth how blockchain technol- ogy works and the attacks it can undergo through Bitcoin. Then, the analysis will focus in particular on the double-spend attack on the Sycomore blockchain. The Sycomore blockchain was introduced in an article co-authored by Mrs. Emmanuelle Anceaume in order to address the main weakness of Bitcoin: the low transaction rate. A continuous discrete-time probabilistic analysis will al- low to specify the conditions of success of this type of attack on the Sycomore blockchain.