About password protected numbers files

[Deng-yongbiao]

According to some information on the Internet, encrypted documents are encrypted using ASE-128. So is there a simpler way to determine whether a numbers document is encrypted? I do not need to parse the content of the encrypted document.

[masaccio]

See also #88. The challenge will be that AES-encrypted data is indistinguishable from random noise. It's possible for numbers-parser to unpack the top-level document and spot that it has what looks like Numbers metadata, but no readable IWA files, and infer from this the document might be encrypted. But the only option would be to raise an exception on the Document() class.

[Deng-yongbiao]

I noticed that if a numbers file is encrypted, then almost all iwa files in it are unreadable, that is, the iwa binary stream does not start with 0x00

[masaccio]

The most recent commits on the GitHub main branch include a test for the existence of .iwph in the document, which is an indication it's encrypted. Opening such a document will raise a UnsupportedError.

[daddytigerflying]

is there a simpler way to determine whether a numbers document is encrypted?

Back to you original question, the answer is Yes. Numbers app can be manipulated by AppleScript, and consequent several Python libraries.

For AppleScript, you can check the password_protected property of document:

tell application "Numbers"
        tell front document\n
              return password protected\n
        end tell\n
end tell

Or you can use appscript package:

import appscript
app = appscript.app('numbers')
doc = app.documents[0]
return doc.password_protected()

Hope this helps.

[masaccio]

The Zip that wraps the document contains some files that are indicative of a password-protected file. There is code in place to check for this (see https://github.com/masaccio/numbers-parser/blob/main/src/numbers_parser/iwork.py#L201) but it's not published yet in a release as I just need to tidy up some code elsewhere to return to 100% coverage.