# Vulnerabilities
At the end of the third chapter we warned you that implementations
get messy. This chapter will show it. Some 
attacks and vulnerabilities we will see are indeed the cause of human 
error but others are design faults that originate in blockchain theory.
This chapter is not meant to be an attack on the blockchain, but rather
a critical analysis of the fact that like any technology, blockchain has
shortcomings that can, and should, be addressed.