  The new generation of security threats has been promoted by digital
currencies and real-time applications, where all users develop new ways to
communicate on the Internet. Security has evolved in the need of privacy and
anonymity for all users and his portable devices. New technologies in every
field prove that users need security features integrated into their
communication applications, parallel systems for mobile devices, internet, and
identity management. This review presents the key concepts of the main areas in
computer security and how it has evolved in the last years. This work focuses
on cryptography, user authentication, denial of service attacks, intrusion
detection and firewalls.

Cryptography and Security