Custom fields unique identifier

I'm looking at buying the business edition for a client.
Currently we have a php script that looks at a folder full of images and creates a table showing the images and a list of options (sizes) that they can select.
Once they have selected the product they pay via paypal.
The code creates a unique identifier for each photo i.e.

43556_6x4_colour_a1234

43556 = photo name
6x4 = size wanted
colour = colour
a1234 = unique customer id

Question is, can the custom fields be used to create a unique code such as this? If so, will definitely be buying and recommending to our other clients.