I’m willing to create a system of transferable documents (identified by it’s ID) whose author can transfer his ownership of that document to another person (identified by his/her ID).
- Alice; owner of document 1.
- Alice transfers his ownership of that document to Bob.
- Now: Bob is owner of document 1.
- Alice says she is the owner of document 1, but she fails.
(Item 4 is very important)
We can make sure that the system with it’s author remains untouched by using digital signature. But if Alice made a copy of that document signed when she was the owner, there would be no way to prevent her from saying she is not the owner of the document.
So we would need something to make a signature to expire whenever it is transferred.
IF I HAD A DATABASE: I would simply add that signature to a ban list.
Are there any solutions to preserve the uniqueness of this document?