  Blockchain technology has been gaining great interest from a variety of
sectors, including healthcare, supply chain and cryptocurrencies. However,
Blockchain suffers from its limited ability to scale (i.e. low throughput and
high latency). Several solutions have been appeared to tackle this issue. In
particular, sharding proved that it is one of the most promising solutions to
Blockchain scalability. Sharding can be divided into two major categories: (1)
Sharding-based Proof-of-Work (PoW) Blockchain protocols, and (2) Sharding-based
Proof-of-Stake (PoS) Blockchain protocols. The two categories achieve a good
performances (i.e. good throughput with a reasonable latency), but raise
security issues. This article attends that analyze the security of the second
category. More specifically, we compute the probability of committing a faulty
block and measure the security by computing the number of years to fail.
Finally, to show the effectiveness of the proposed model, we conduct a
numerical analysis and evaluate the results obtained.
