Topic: Selected cryptographic schemes implemented in the blockchain system
Abstract: During the last decade, we have observed the rise of the blockchain technology from simple distributed ledgers to powerful programmable networks. This master thesis aims to explore the computational capabilities of these systems to implement selected cryptographic schemes. The work covers the design and implementation of a distributed timestamping system based on a protocol combining Schnorr signatures and Pedersen commitments in which data is stored and validated using Ethereum network. The proposed system utilizes a smart contract to store protocol data and mediate the flow of information between server nodes which issue timestamps and client nodes who can submit data for timestamping and call the verification procedure on any recorded timestamp. We evaluate the efficiency of the implemented protocol based on gas fees, memory usage and execution time. The work discusses the advantages and limitations of Ethereum network observed during the development of the system, such as the public storage which on one hand provides full transparency and on the other prevents us from keeping any secret on the network.