Blockchain 

Topic Description

A distributed ledger (often referred as DLT, from Distributed Ledger Technology) is a decentralised repository of data managed and maintained by many participants, without necessity of assuming trust between each other. In general, the participants have the same rights and control over the repository, and communicate directly between themselves in a P2P fashion to propose and notify updates of such repository. Often such updates satisfy an append only rule to guarantee the data immutability property. There is no need for intermediaries nor for a centralised controller, since the participants employ a distributed consensus algorithm to reach a decision on the updates to be made to the repository.

Blockchain technology is just one possible technology to implement a DLT. A blockchain implements a distributed ledger by grouping records (i.e. ledger state updates) into blocks that are made tamper resistant by adding a cryptographic signature of the block data. Usually this is achieved by adding a cryptographic hash of the entire block content in the block header. The blocks are than chained together by back-linking each block to the predecessor in a tamper-resistant way. Again, the most common way of achieving this is through cryptographic hash functions, by adding the hash of the previous block in the following block header. By making each block recursively dependent on both its content and the previous block in the chain, such block becomes dependent on the entire content of all the blocks before it, all the way to first block created (often called the genesis block). This way it is not possible to modify any data inside a block without invalidating all the subsequent blocks.

Such a technology can be used by entities wishing to be more transparent and accountable, as well as the ones wishing to cut costly trusted third party intermediaries. In fact, the traditional task of ensuring trust is taken over by the technological layer. Cutting the need for intermediaries results in less costs, more transparency, and greater efficiency. Furthermore, the integration of blockchain with cryptography allows for proof of ownership and authorship of information, while its nature as digital asset allows embedding executable code as data, allowing the usage of smart contracts. This allows for a wide range of applications well beyond the first use case of Bitcoin in particular and cryptocurrencies in general.

Our group is currently investigating several Layer-2 technologies for blockchain, among these

Selected Publications

Software and Datasets