In this answer, it is mentioned that facts about a copyrighted work, such as lists of how many times they use each word, are not really derivative works because, as facts, they aren't subject to copyright. So it is not a violation of the normal license of, say, a book to prepare or publish a list of words used and their counts.

I could also make a table of frequency digraphs, though: there are 10 instances of the first most frequent word followed by the second most frequent word, 8 of the first most frequent word followed by the third most frequent word, and so on. It seems likely that that table would also be just a fact about the book, not really subject to copyright.

And I could make a table of digraph frequencies on the digraphs themselves: the third most common digraph is followed twice by the eighth most common digraph, and so on. Kind of a weird fact to explain, but still a genuine fact. It's not an obviously fake fact, like a jillion-digit number that just so happens to reveal the book when stored in a file in binary and opened in Notepad.

But if I repeat this process with enough levels, I eventually have a collection of facts that can be true of only one possible book, and the collection taken together could (assuming I am right about the correctness of this exact system) be used to practically reconstruct the book.

Am I actually allowed to publish all of these facts? Or do I have to publish only a subset of the facts, because the whole collection taken together actually is a copy of the book?

Can I hang up a sign "Facts sufficient to reconstruct $POPULAR_BOOK, 10¢ each"? Or am I obligated to not encourage or deliberately facilitate book reconstruction, without having a reason to believe the reconstructor would be doing it under a license or under fair use?

1 Answer 1


So, you're asking if enciphering a copyrighted work is copyright violation?


What you have described is an extremely inefficient cypher of the copyrighted work - more clumsy and cumbersome than ASCII but conceptually the same thing. This is a copy of the work, just one that requires additional effort to read.

  • So any collection of facts sufficient to reconstruct a copy of the work, legally, is a copy of the work, even if the individual pieces of information individually are not excerpts or real creative works subject to copyright themselves?
    – interfect
    Commented Oct 25, 2023 at 14:35
  • What if the "cipher" isn't inefficient, but is rather a simple recipe for transforming a public-domain work into one for which copyright is claimed, e.g. 'Starting with the public domain song "Good morning to all", replace every occurrence of "Good morning" with "Happy birthday", and change the last word "all" to "you"'?
    – supercat
    Commented Jan 26 at 23:39

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .