I feel like this creates a hash value and the real question is how unique of a value does it represent and how easy it is to narrow it down given throwing a dictionary at it. Similarly, unknown names could likely be teased out like a one-time pad. If they appear in multiple sentences then their randomness quickly repeats and becomes something that potentially could be isolated from the rest of the words around them. This would probably be a fun problem for a cryptography class to work on.