User Validation: Saving machine/browser profile

I'm attempting to add a validation workflow to my login, similar to what you might see on a bank website, where it emails you a validation code if it doesn't recognize your machine/browser combintation.  

Adding the validation email was very straightforward, but what I'm having trouble finding is a start to how you find and save some sort of signature that signifies that the machine/browser is 'trusted', so that they don't need to go through the email validation workflow every time they log in.  

Thank you in advance for your help.
Hi Thomas,

My first idea would be to use a cookie on client side. I did a search and found this that might help if you don't want to use cookies: 

Thank you, I think that was exactly what I was looking for.