I would like to make a digital equivalent of an envelop with a seal that must be broken to open. The idea is that it can be seen that the seal has been broken. I know that it is impossible to make this 100% safe, but for the use case I am imagining, it is sufficient that very difficult to open the seal without "breaking it". I am thinking of storing a text file with some important information.
Edit: This is as much a thought experiment as something I've actually decided to do. I kind of figured that the data probably have to be stored remotely, like the web server or email auto-reply suggestions, but I was wondering if somebody could come up with a unique solution for storing it locally. I suppose storing just the encryption key remotely or IRL may be as close as we can come.