  In the last years, identity management solutions on blockchain were proposed
as a possible solution to the digital identity management problem. However,
they are still at an early stage and further research needs to be done to
conclude whether identity systems could benefit from the use of blockchain or
not. Motivated by this, we investigate identity management solutions on
blockchain intending to give the reader an overview of the current status and
provide a better understanding of the pros and cons of using such solutions. We
conduct an analysis on ten of the most known implementations, with a focus on
privacy and security aspects. Finally, we identify existing challenges and give
new directions for research.
