I'm imagining some kind of additional option given to you when you right click a paper with a cybersun pen in hand to Forge Signature, at which point you're given a gui which would allow you to type in ANY NAME using ANY FONT provided in the signature section of the character creation screen.
So, theoretically, you would have to know a person's exact signature font to accurately forge them, while at the same time being able to forge a signature for a person that doesn't exist.
