I don't know, following that logic it would be impossible to claim copyright over an encrypted file as it's basically also just a very large random number, even if I can reassemble the original file if I have access to the cryptographic key. I think you could probably share the encrypted file on the web if you don't share the key, as no one can know what the file contains (assuming the cryptographic method is secure). Together with the key this data will become copyrightable though as there is an easy way for any user to re-assemble it on his/her computer.
So I'd say downloading individual randomized blocks is probably not problematic and akin to downloading an encrypted file without having access to the key. Downloading the URL that points to the descriptor list might be problematic though, as this will allow you to "decrypt" the other blocks.