MSc thesis of Nikolaos Lamprou
Centralized protocols and anonymous decentralized systems
Supervisor: Aristeidis T. Pagourtzis
In the present thesis, firstly we study the centralized protocol of the blank signature , a new type of signature that was published by Christian Hanser and Daniel Slamanig , in 2013,as well as the security of this scheme. The existence of centralization in the above protocol, as we will see, is a crucial part because if we ignore it, one of the participants can find a trapdoor to the protocol. Consequently we refer to the decentralized protocol of Bitcoin  that was published by Satoshi Nakamoto ,in 2008 ,as well as the security with which it provide us , , and we also refer to some smart contracts  that has been built on top of this ,which use its decentralized character. Lastly, we refer to the new decentralized system, the Ethereum,, that was introduced by Vitalik Buterin, Gavin Wood ,in 2013- 2014 (during this thesis ,its development has been growing),which advantages it wants to achieve in comparison with the Bitcoin as well as the formal way of its function .Defended: May 6, 2015.