Knowing applied cryptography is one of the keys to proper wireless network hardening. In this chapter we tried to introduce its foundations in a language understandable to IT professionals, supplemented by real-life examples of applied cryptography successes and failures. We hope that after going through this chapter you will never select default or random cryptographic safeguards without giving it proper thought first. This is very helpful when designing your VPN or writing cryptographic application with quality of service and performance in mind, taking into account the specific characteristics of the hardware platforms used.
Another useful outcome of this chapter is better understanding of motivations and planning behind the cipher's selection and implementation by wireless standard developers from WEP to 802.11i. Instead of simply handling away the structure and operation of AES, we took a dialectic approach, explaining how and why the AES and its 802.11i CCM operation mode were developed and selected. Of course, not all cryptographic solutions are limited to symmetric ciphers. The next chapter continues the journey, explaining the ciphers used for data integrity checks, data and user authentication, and secure key exchange. These safeguards are of prime importance on wireless networks and should be understood well to protect your WLAN efficiently.