Using certificates or HW/SW tokens to identify client systems

Hello, everyone,

Are there any tried and true authentication methods using certificates or hardware/software tokens? Preferably something that can be easily integrated into ColdFusion.

I was approached by a friend to design and develop a web application that will cater to a specific industry, and I want to make sure that it cannot be accessed at all by any computer that does not have the proper certificate or token.

Thank you.