I mean, really, why would it be encrypted?

[Stephen Carlson]

Simply question - why encrypt the VM?
...

So let's look at the mindset. Why would anyone encrypt a whole book? Because they thought it was full of personally important and confidential information? In which case, it would be the most important book from the era we have - because it would be unique. Nobody else from the era thought it important enough to encrypt their entire notebooks, let alone create an entirely new unbreakable encryption system.

That's a great question. I suppose fundamentally that the reason to encrypt anything is to hide the plaintext from unauthorized readers. That's sounds like a truism, even tautological, but let's use it as a starting point.

Of course there are other ways to the hide the plaintext. Physically, for example. The access to the book itself can be physically controlled, put under a lock and key. One benefit is that encryption protects the plaintext even when the medium is not sufficiently protected. You can see why letters would be encrypted, because the sender may not have full control over the physical security of the plaintext until it reaches the recipient. For a book, however? Encryption would be a (further) protection against theft or plagiarism or something like that. But ordinarily, I think that keeping a book of secrets in a good hiding place would be enough.

As to authorization, this could get into a teacher-pupil relationship, where the content of the plaintext is imparted only to a paid-up pupil. Thus, the content is viewed as a valuable and the encryption is to exert further control who can access it. In other words, there could be an economic reason for the additional control. Or, it could be some sort of an intellectual challenge. Hard to say, possibile motivations could be endless.

It may even possible that there are no authorized readers of the plaintext beyond the creator of the VM. Perhaps we have a Da Vinci situation where the creator wants to keep the work secret from rivals. Alternatively, the encryption could be used to hide the lack of content or relevance of the plaintext. For example, the creator VM drew fanciful pictures but had no content to explain them. Such a person could take a known but irrelevant plaintext (for example, Genesis or other widely copied book) and encrypt that to make it look like the pictures have accompanying explanations. In this case, the key may never be disclosed because the nature of the VM would be exposed.

But encryption with no authorized readers is awfully close to asemic writing. If the encryption is strong enough (or loses too much information), we may never be able to tell the difference.