Internet Security Algorithm is any type of method that can be used to preventing the information over internet from being hijacked by somebody else (intruder) and decoded by the intruder. First impression of 'Internet Security Algorithm' to me was "It is so confusing.. all the technical documents about these algorithm looks like encrypted document even though it is written in plain text" -:) So my first questions was "Where to start ?". "Which one I have to study first ?". After long time of struggling period, the guideline that I came out with by myself is i) Study the basics concept of IKE (Internet Key Exchange) ii) Then study the basic concept of AAA (Authentication, Authorization, Accounting) iii) Then study the specific types of AAA like RADIUS or DIAMETER The final goal is to understand a specific algorithm like RADIUS or DIAMETER.. Since these algorithms are a kind of AAA algorith, we need to understand basic concept of AAA before it. Since AAA is made up of multiple steps of key exchanges, we need to understand the basic concept of IKE first. For several month from now, I will keep updating these pages following the sequences described above.