Lets say there are 3 people.
- 1st signs a message and sends it to 2nd using public key encryption
- 1st deletes the message
- 1st tells 2nd to forward his message
- 2nd forwards the message to 3rd
How can 1st verify the message was forwarded untampered without trusting 2nd or 3rd and without finding out the message contents again?
A terrible idea is to have 3rd give his private key to a 4th who will confirm to 1st that his message was untampered.
I am new to this so if what I want to do is impossible a heads up would be deeply appreciated.