What is the easiest way to deploy an ASP.NET application with SSL support (and no client SSL errors/warnings)? Do I need to buy a certificate? Do I need to change anything within my ASP.NET application or is everything solely done via IIS? Any tutorials?
You do need to buy an SSL cert from a trusted auhority if you want SSL support and no annoying/suspicious dialog boxes. Thawte/verisign is a popular opton and their site will provide thorough instructions for insalling in IIS.
What is the easiest way to deploy an ASP.NET application with SSL support (and no client SSL errors/warnings)? Do I need to buy a certificate?
Yes, you'll need a valid SSL certificate. There are several to choose from. We've been using DigiCert for a few years and have been very happy with the service. They have a tutorial for most web servers that will explain how to generate certificate request and install it. You may want to look into wildcard certificates if your organization has multiple sub-domians.
One other thing I've found helpful with DigiCert (and other companies may have this as well) is there test form. It helps you verify that the certificate is installed correctly, is valid, and dns is resolving correctly. It has helped us troubleshoot problems that have come up where end users would get a certificate error and everything looked good, but something was mis-configured on one of a bunch of servers.
No affiliation with this company... I've just had good experiences working with them.
Do I need to change anything within my ASP.NET application or is everything solely done via IIS?
Without a great deal of detail, it is difficult to say with certainly, but generally speaking your application will not require changes. You may find that you'll want to make changes (making sure a specific page is being accessed via ssl for example), but again, there are other ways to configure this.
The certificate is installed via the certificates snap-in (you'll see this in the instructions provided by the certificate provider). Once installed correctly, you will go to the properties of your website and enter in the SSL port (443 by default) and/or add your SSL identities if you have multiple sites. If you want the all pages to be secure, you can set that up in the directory security tab. You should really do this only if you're creating a secure subdomain as SSL will slow down your site if the whole thing is SSL.
There are of course more details and options, but hope this helps you get going in the right direction.
The choice of witch type of certificate to use (commercial or not) depend on the purpose of your https site. This guide about ssl encryption (https) in IIS can help you to decide.