I have been looking at either coding from scratch a basic login page + session management user validation for a new website I intend to build.
I am wary that this may not be the safest thing for me to do on my own, so I am contemplating using joomla or wordpress for basic user authentication and then having the rest of the site pretty much customised. Is this a good idea, or am I going against how they were designed and is there a better framework I could be using for this simple task? I am not too concerned with language but asp.net or php are definitely preferred.
For ASP .NET you should use ASP .Net Membership
a series of tutorial regarding to implement asp .net membership can be find here