There's a difference between a valid ticket, and a legit ticket, valid tickets would be tickets whose titlekey are correct, you usually end with non valid tickets from 3DS to CIA dumps and stuff, by deleting or overwriting the ticket with a valid one, or a valid CIA you should end up a valid ticket, the difference with a valid ticket is that you can Redownload games from the eShop.
Legit tickets on the other hand would need to be signed, and signing files is something only Nintendo can do, (Piracy works as in the CFW disables the signature check, so we can have and play unsigned content). You would need to purchase the content you want to have a signed ticket.