Department of Computer, Control and Management Engineering

Decentralized cryptocurrency systems offer a medium of exchange secured by cryptography, without the need of a centralized banking authority. Among others, Bitcoin is considered as the most mature one. Its popularity lies on the introduction of the concept of the blockchain, a public distributed ledger shared by all participants of the system. Double spending attacks  and blockchain forks are two main issues in blockchain-based protocols. The first one refers to the ability of an adversary to use the very same  bitcoin  more than once,  while blockchain forks cause  transient inconsistencies in the blockchain.

In this paper, we show through probabilistic analysis that the reliability of recent solutions  that exclusively rely on a particular type of Bitcoin actors, called miners, to guarantee the consistency  of Bitcoin operations, drastically decreases with the size of the blockchain. 

 

Romaric Ludinard is associate professor at ENSAI, the national school for Statistics and Information Analysis, where he manages the Data sciencist specialization. His research mainly focuses on models, safety and performance of distributed systems. He worked at Inria Rennes - Bretagne Atlantique as research engineer on byzantine fault tolerance in large scale distributed systems and at Supelec Rennes on anomaly based intrusion detection systems. His phD was prepared in conjonction with Inria and Technicolor R&I and related to fault characterization in large scale networks. His research now focuses on Blockchain protocols and their guarantees.