I posted a similar question but I see that I did it incorrectly. For this reason I post it again hoping not to cause any problem.
I have the following situation:
Alice often sends funny jokes to Bob. She does not care about the confidentiality of these messages but wants to get credit for the jokes to prevent Bob from claiming authorship of or modifying them. How can public-key cryptography achieve this?
I have provided the following answer but I need feedback from an expert:
It is clear that we are talking about an ideal situation because Bob can create a new message and type each joke entirely. However, we can do the following taking in consideration some restrictions for Bob.
If confidentiality is not important then it is not necessary to encrypt the messages. What Alice can do is to include a text at the end of each joke stating she is the author, for example, “Alice is the author of this joke”. After that, Alice digitally signs each message with her private key producing a hash of the message and sends it to Bob along with her public key. When Bob sends a joke to Carol, he sends Alice’s original message including Alice's signature and Alice's public key. This way, if Bob modifies the message, the digital signature will not be successfully validated by Carol because there will be a different result of the hash meaning that the original message suffered a change in some way.
I will very much appreciate your comments.