I'm still getting my head around public/private key cryptography, and I can't quite work out how to ask the right question to get an answer for this problem, but here goes!
- Alice, Bob, Carol, and Dave are all in a secret society which writes exquisite corpse stories.
- First Alice writes a line into a file; then she sends this file to Bob, Carol and Dave. Each of them might write a line too, and share it with the group again.
- Nobody outside the secret society should be able to read their story, but each of them should be able to read the whole story.
- After a while, Alice invites Edgar into the secret society. He can now read all the previous lines in the story, and add his own.
How would I make this scenario happen? Does each person have their own key? Is there a single key pair representing the society as a whole? Is there any reading I could do or terms I could search which would help me understand this scenario?